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Stormwater Ponds in Coastal South Carolina Appendix A4 – Annotated Bibliography

Aelion, C. M., & U. Warttinger. 2010. Sulfide inhibition of nitrate removal in coastal sediments. Estuaries and Coasts 33(3):798-803.

Aelion and Warttinger (2010) examined denitrification rates in coastal sediments, specifically focusing on the effects saltwater influxes have on these rates. Two ponds were chosen for the study, Kiawah Island pond 107, which is a freshwater pond and surrounded by golf course greens, and the impounded wetland pond Blue Heron, which is located on the wide end of the island. Sediments and water samples were collected from March to May 2007, and experiments were conducted by adding potassium nitrate, magnesium sulfate, and hydrated sodium sulfide to sediment samples and determining DNF rates. Results found that the freshwater pond sediments were able to remove added nitrate under baseline conditions due to low background concentrations and high DNF rates. This is likely due to elevated microbial activity from frequent influxes of nutrients. TOC and TC was much less at the freshwater pond than the wetland site but this did not affect DNF or SO42– removal. Added SO42– was removed faster in the freshwater pond sediments, however high concentrations could result in the inhibition of NO3– transformation and buildup in the sediments.

Adams, L. W., Dove, L. E., and T. M. Franklin. 1985. Mallard pair and brood use of urban stormwater-control impoundments. The Wilson Bulletin 13(1): 46-51.

Adams et al. (1985) documented waterfowl use of several types of urban stormwater-control impoundments in Columbia, Maryland. Three lakes, 22 permanent water ponds (further classified as deep and shallow), and nine detention basins were surveyed for waterfowl. Results found that breeding pairs of mallards preferred shallow pond habitat, and there were no mallards observed using detention basins. Permanent water ponds could provide important habitat in urban and suburban areas.

Adams, L. W., Dove, L, E., and T. M. Franklin. 1985. Use of urban stormwater control impoundments by wetland birds. The Wilson Bulletin 97(1): 120-122.

Adams et al. (1985) details the same methodology as the previous publication on waterfowl to examine wetland bird usage of urban stormwater control impoundments. Spotted and Solitary sandpipers and Red-winged Blackbirds were the most common species found using permanent water ponds and lakes. Results found that shallow and deep ponds were used significantly more than lakes

Bettez, N. D., and P. M. Groffman. 2012. Denitrification potential in stormwater controls structures and natural riparian zones in an urban landscape. Environmental Science & Technology 46: 10909-10917.

The riparian zone is typically a “sink” for nitrate, removing N through denitrification. However, urbanization has impaired streams and riparian zones, decreasing the amount of N removed. Stormwater control measures such as wet ponds, dry detention ponds, and detention basins have the potential to increase denitrification, but there is limited information as to how their removal capacity compares to natural riparian zones. Potential denitrification using denitrification enzyme assays was examined in 13 SCMs (including 1 wet pond) within Baltimore County, MD. Bettez and Groffman (2012) found significant differences in DEA between SCMs and natural riparian zones with higher potential denitrification in the stormwater structures. These results suggest SCMs may act as hotspots of denitrification, likely due to their design, which facilitates the interaction between nutrient rich stormwater and denitrifying sediments.

Birx-Raybuck, D. A., Price, S. J., and M.E. Dorcas. 2010. Pond age and riparian zone proximity influence anuran occupancy of urban retention ponds. Urban Ecosystems 13:181-190.

While urbanization results in habitat fragmentation and the destruction of natural areas, urban retention ponds can provide suitable habitat for some amphibian species. The suitability of these habitats depends upon many landscape and local factors. These ponds collect contaminants from stormwater runoff and may act as ecological traps, with studies finding they can limit breeding success and species richness. Birx-Raybuck et al. (2010) wanted to examine the influence of landscape features on retention pond use, specifically looking at the effects of pond age and distance to nearest riparian zone on amphibian occupancy by five species in the Charlotte-Mecklenburg metropolitan area of North Carolina. Results determined that urban retention ponds do provide important habitat for many frog and toad species. Anuran presence was negatively correlated with distance to the nearest riparian zone, and pond age, while it affected species differently, played an important role.

Borden, R. C., Dorn, J. L., Stillman, J. B., and S.K. Liehr (1997). Evaluation of wet ponds for protection of public water supplies. North Carolina Urban Water Consortium and WRRI of UNC. Project No. 50184. 140 pp.

Borden et al. (1997) examined the pollutant removal efficiencies of two wet ponds in the city of High Point (NC) that were constructed to improve water quality in their reservoir system.  Nitrogen pollution, a concern in most urban areas, can be removed or transformed through biological transformations, sorption to sediment, and plant uptake. Plant species therefore have a significant impact on the amount of nutrients permanently removed in control structures. Detention ponds have proved to reduce pollutant concentrations in runoff and reduce peak runoff rates, and efficacy of these ponds depends on many design factors.  Important considerations include pond size relative to drainage area, shape, depth, and slope. Solids, alkalinity, TOC, FC, BOD, and nutrients were measured monthly and during storm events over a one-year period.  Seasonal and spatial variations in pollutant concentrations and loads were found at both ponds.  While most studies have focused on pollutant removal through sedimentation, Borden et al. (1997) also evaluated biological processes focusing on algal growth and nutrient cycling.  The two ponds, Davis Pond and Piedmont Pond, had very different pollutant loads and concentrations initially entering the two ponds, due primarily to surrounding land uses.  Davis pond was hypereutrophic with high chlorophyll a concentrations. Piedmont pond had better water quality with moderate chlorophyll a concentrations that were limited by low levels of DP and DN. Pollutant removal efficiency varied with multiple parameters.  Annual TSS removal efficiencies were 60% in Davis Pond and 20% in Piedmont pond, not meeting NC DEHNR guidelines of 85% removal. Davis pond moderately removed fecal coliform. Davis pond and Piedmont Pond TP removal rates were 46% and 40%, respectively.  Significant TN removal in Davis pond was due to algal uptake during the growing season, but overall removal rates were lower than in Piedmont Pond. Borden et al. (1997) details several different models and approaches for predicting TSS trap efficiency in wet detention ponds.

Brand, A. B., and J.W. Snodgrass. 2010. Value of artificial habitats for amphibian reproduction in altered landscapes. Conservation Biology 24(1): 295-301.

Stormwater ponds have the potential to serve as ecological traps for anurans; they provide suitable habitat for amphibian species and expose embryos and larvae to accumulated pollutants. Brand and Snodgrass (2010) evaluated the availability and breeding use of artificial and natural wetlands by amphibians in suburban and forested landscapes in Baltimore County, Maryland. They documented six species using the various wetlands, however breeding occurred primarily in the anthropogenic wetlands (i.e., stormwater ponds, artificial wetlands). These anthropogenic wetlands proved to be important to the reproductive success of the amphibians and may be the only productive habitats in areas where natural wetland densities are low. Stormwater ponds in particular had a more conducive hydroperiod for amphibian reproduction and are important habitats in altered landscapes.

Brock, L. 2005. Water quality, nutrient dynamics, phytoplankton ecology and land uses within defined watersheds surrounding six detention ponds on Kiawah Island, South Carolina. MES Thesis, College of Charleston, Charleston, S.C. 

Relatively little research has been conducted on the ecology and phytoplankton community structure of stormwater detention ponds. Stormwater ponds face environmental and cultural issues, such as the repeated occurrence of HABs, and due to their use as recreational outlets, they facilitate human exposure to harmful phytoplankton species. Brock (2005) examined the relationship between land use, environmental properties, and phytoplankton community dynamics in six brackish stormwater detention ponds on Kiawah Island. Specific objectives were to determine whether variability in nutrient concentrations are due to seasonal effects, whether there is an association between bloom species and salinity, and whether a relationship exists between land uses and dissolved inorganic nutrients. Brock (2005) found no significant relationship between temperature and nutrient variables but a negative relationship between salinity and NO2+NO3, DIN, and PO4. Ponds with similar salinities tended to have the same community composition, however salinity did not directly influence species occurrence as Cyanophyceae species were frequently found in high brackish waters. The phytoplankton community structure fluctuated seasonally but was primarily dominated by Dinophyceae and Bacillariophyceae species with higher occurrences of Cyanophyceae and Raphidophyceae species in the summer.  Each pond receives water from distinctly different watersheds that vary in size and shape, however Brock (2005) found no direct relationship between land use and nutrient parameters.

Bunker, K. 2004. A hydrological assessment of two detention pond watersheds in an urban coastal landscape. MES Thesis, College of Charleston, Charleston, S.C.

Bunker (2004) assessed the hydrology of two wet detention ponds on Kiawah Island. Ponds K70 and K67 were chosen as sampling sites. While similar in size and volume, the two ponds varied in acreage, land use, and stormwater volume. Analysis revealed that water quality within the detention ponds was primarily influenced by land use and the surrounding watershed. At K67, data indicated that groundwater flowed laterally into the detention ponds from one side and out on the other, while vertical groundwater movement fluctuated.  Data found a mixing of groundwater and pond water around the perimeter of the pond, supporting nutrient exchange between these two systems. This indicated that groundwater can act as a source of nutrients to the pond and also transport nutrients away from the pond to surrounding water bodies. At K70, groundwater moved into the pond from the surrounding watershed. Fluctuation in groundwater flow resulted in some water moving from the pond towards the marsh and groundwater moved vertically in both directions. This elucidates the potential for stormwater ponds to negatively impact estuarine systems that are considered nitrogen-limited and also indicates that detention ponds may be a source of nutrients into aquifers. Bunker (2004) also found high levels of inorganic nitrogen in the groundwater leaving the detention pond systems, which is indicative of their inability to process/retain nitrogen. Pond K70 had lower overall nutrient concentrations, which are assumed to be the result of greater plant uptake due to greater vegetative buffering.

Burleson, R.W. 2002. Stormwater quality management planning in coastal South Carolina [Abstract]. Proceedings of the Water Environment Federation 2:1463-1477.

Numerous shellfishing areas have been closed permanently or on a conditional basis over the years, indicating that the current volume methods for controlling stormwater runoff may be not be effective. Proposed developments now are required by SCDHEC to demonstrate that discharge from the site will not impact water quality.  SCDHEC had no approved methodology to compute nonpoint source loadings, and current retention/detention methodology is not accurate. This paper outlines methodology for computing NPS loadings coinciding with BMP implementation using three developments in the Myrtle Beach area as examples.

DeLorenzo, M. E. and M.H. Fulton. 2009. Water quality and harmful algae in Southeastern coastal stormwater ponds. NOAA Technical Memorandum NOS NCCOS93, 27 pp.

Fertilizer application, fecal inputs, and additional urban runoff have led to pollutant loading and eutrophication within stormwater ponds. Elevated nutrient concentrations result in excessive algal growth and the proliferation of harmful algal blooms. SCDHEC-OCRM conducted a baseline study of 112 coastal stormwater ponds and found high chlorophyll a concentrations (>40 ug L-1 in approximately 32% of the ponds) even though nutrients levels were low and DO was moderately high. Many HABs species have been documented in S.C. coastal stormwater ponds, and as the prevalence of HABs has increased over the past two to three decades, they have become a globally growing concern. Toxins within brackish and freshwater systems are primarily produced by cyanobacteria and can pose a health risk to those who recreationally use the pond, and to wildlife and pets. Common cyanobacteria species include Microcystis, Anabaena, Nostoc, Oscillatoria, many of which have been found in S.C. stormwater ponds. Dinoflagellates have also been associated with fish kills in coastal waterbodies. In SCAEL samplings, Pfiesteria-like organisms (PLOs) were commonly found in mid-high salinity stormwater ponds. Using light microscopy, two Kiawah island ponds (K2 and K5) had a high prevalence of PLOs (67% and 80%) which were confirmed with PCR in 47% and 82% of the samples respectively. Other common dinoflagellates associated with blooms include Karlodinium veneficum, Kryptoperidinium foliaceum, and Scrippsiella sp..  Raphidophyte HAB species (Heterosigma akashiwo, Chattonella subsalsa, Chattonella verruculosa, Fibrocapsa japonica) were also commonly found in brackish ponds on Kiawah Island, S.C. and were not reported in a survey conducted pre-development of the island.

DeLorenzo, M. E., Thompson, B., Cooper, E., Moore, J., and M.H. Fulton. 2012. A long-term monitoring study of chlorophyll, microbial contaminants, and pesticides in a coastal residential stormwater pond and its adjacent tidal creek. Environmental Monitoring and Assessment 184(1): 343-359.

In addition to providing flood control, stormwater ponds are utilized for recreational purposes. However, the low circulation, high nutrient levels, and warm temperatures found in these ponds allow bacteria and algal species to flourish, posing a risk to human health. DeLorenzo et al. (2012) conducted a long-term study on water quality within stormwater pond Lake Edmund (LE) (James Island, S.C.) and the tidal creek it drains into Kushiwah Creek (KC). Stormwater pond LE serves as not only a recreational resource for residents within the community but also a habitat for wildlife. Water quality parameters were evaluated for chlorophyll, fecal coliform, and pesticide levels, and the tidal creek was screened for the pathogenic Vibrio bacteria.

Results found chlorophyll levels to be significantly lower in the winter for LE and no significant differences between seasons in KC. All of the LE samples had chlorophyll levels that exceeded the EPA’s eutrophication standard of 4.1 ug/L for freshwater. Analysis of the complete data set found chlorophyll levels to be statistically significant and positively correlated with monthly air temperatures and accumulated rainfall. Chlorophyll levels were greater in the stormwater pond than the tidal creek during summer and fall seasons. DeLorenzo et al. (2012) found higher fecal coliform bacteria (FCB) levels in the tidal creek than in the stormwater pond. Maximum monthly FCB concentrations reached up to 1,247 CFU/100 mL in LE. Antibiotic resistance to E. coli was also evaluated. Of the 540 isolates tested, 90% were found to be resistant to at least one antibiotic, which they attributed to pet waste in LE.

To improve water quality in these stormwater pond systems, management actions such as reducing fertilizer use and pesticide use, properly disposing of pet waste, and planting more vegetated buffers around the pond should be implemented. Stormwater ponds are often tidally connected to adjacent estuaries through direct piping, groundwater movement, or overtopping events. Therefore, managing water quality in stormwater ponds is an integral part of maintaining the overall health of the marine ecosystems.

Drescher, S. R. 2005. Capacity of nitrogen processing in watersheds surrounding detention ponds in Kiawah Island, South Carolina. MS Thesis, College of Charleston, Charleston, S.C.

Development decreases the biogeochemical transformation function of watersheds. In residential and golf course areas where runoff is managed through stormwater detention ponds, nutrients are often remineralized instead of leaving the system through nitrification or denitrification processes. These ponds are highly affected by eutrophication and algal blooms, which can result in water quality impairment in receiving water bodies. Drescher (2006) quantified denitrification capacity rates in terrestrial soils and pond sediments in two ponds on Kiawah Island (K67 and K70). Basic water quality parameters were taken from October 2003-December 2004. Main differences included higher salinity at K70 (16.9 ppt) compared to K67 (5.9). T, DO, and pH were comparable throughout the study. Sediment pore water profiles showed NH4+ to be consistently high in both ponds, while NO3 decreased with depth in winter 2004. NO3 remained low at both ponds during the summer and fall.  High nutrient and DOC content in the pore water of pond sediments potentially indicates that these soils are biogeochemically active and may have a high capacity for dentrification, however they are likely limited by low DO levels. N:P ratios in pond sediments were 4.3:1 for K67 and 3.2:1 for K70, which is indicative of nitrogen limitation and high phosphorous availability. Pond sediment denitrification rates ranged from 0.04 to 2.48 nmol N20 gdw-1h-1 in pond K67 and 0 to 1.57nmol N20 gdw-1h-1 in pond K70. Dentrification could prove to be an important process lessening eutrophic conditions within these ponds.

Drescher, S.R., Sanger, D.M., and B.D. Davis. 2011. Stormwater ponds and water quality. Stormwater Journal. Retrieved from

In the southeast, there is evidence that stormwater ponds can negatively impact water quality, human health, and be incubators for harmful algal blooms (HABs).  From May to October of 2006, SCDHEC-OCRM conducted a baseline study, sampling 112 stormwater ponds. Information was gathered on pond dimensions, distance to nearest receiving water body, primary surrounding land use, and rainfall.  Samples taken in each pond were measured for basic water quality parameters, nutrients, fecal coliform bacteria, Chl phaeopigment, TSS, and algal screening.  72% of the ponds were within 0.5 miles of a receiving water body, indicating a high potential for these ponds to connect and discharge directing into tidal creeks.  Results from the water quality analysis found that 23% of the samples had fecal coliform levels greater than 400 CFU’s/100 mL-1. Chl a data showed that 22% of the ponds could be classified as hypereutrophic and 35% as eutrophic.  Live screens of the phytoplankton community found approximately one in five contained toxin producing species, supporting research that has found ponds to be incubators of HABS. Results from this research suggest that stormwater ponds may be a concern for receiving water bodies and that additional studies and management options are needed.

Drescher, S. R., Law, N. L., Caraco, D. S., Cappiella, K. M., Schneider, J. A., and D.J. Hirschman. 2011. Research and policy implications for watershed management in the Atlantic Coastal Plain. Coastal Management 39(3): 242-258.

Stormwater management was previously based off practices developed in the Piedmont Region. These practices are inadequate for the Coastal Plain, which is characterized by a high water table, flat terrain, extensive groundwater interactions, and poorly drained soils. Stormwater management plans are based primarily on flood control and sediment removal and are addressed through the use of wet ponds, dry ponds, and open channels. Stormwater ponds are the most commonly used BMP to address nonpoint source pollution. However, research has proven that while they are effective in reducing flooding, they can also act as “incubators’ for nutrients and can negatively impact water quality and human health. Little data currently exists that examines the pollutant removal efficiency of stormwater ponds. Drescher et al. (2011) recommends the development of new and innovative LID practices for pollutant removal and runoff reduction.

Drescher, S.R., Messersmith, M., Davis, B., and D. Sanger. 2007. State of the Knowledge Report: Stormwater detention ponds in the Coastal Zone. South Carolina Department of Health and Environmental Quality. 1-32.

This report synthesizes the existing research related to stormwater pond water quality, sediment quality, hydrology, and additional measures. Research has found that stormwater ponds typically have poor water quality conditions that result in high algal biomass and fish kills. They often exhibit high concentrations of nutrients, chlorophyll a, chemicals, pesticides, fecal coliform bacteria, and low DO levels. Due to the proximity and usage of these ponds by humans and wildlife, understanding water quality conditions within these systems is important for proper management. This report also identifies future research priorities and gaps in the current knowledge.

Drescher, S.R., Messersmith, M.J., Sanger, D.M., and B.C. Davis. Is better management needed for South Carolina stormwater ponds? South Carolina Department of Health and Environmental Control-OCRM

In 2006, SCDHEC-OCRM conducted a baseline study on stormwater pond water quality, examining 112 ponds that were permitted approximately five years ago in coastal South Carolina. A pollutant removal efficiency study was also conducted to evaluate the performance of two wet detention ponds on Daniel Island, S.C., one of which was a single pond and the other a part of a series of ponds. The baseline water quality study found that most stormwater ponds had very low surface salinity levels (<1ppt), around 20% had low DO (<4 mg L-1), 32% had chlorophyll levels greater than 40 ug L-1, algal blooms and HABs were common, and the highest FCB levels occurred after a rainfall event. Over 37 HAB species were identified in the algal screens, several of which are known to produce toxins.

Bathymetry measurements taken at the Daniel Island ponds showed that both ponds have filled in over time. This reduces water volume and residence time and therefore the ponds ability to detain runoff. Overall pollutant removal efficiencies varied between ponds and by rain events. They ranged from -208-95% for nutrients, -477% to 99% for FCB, and -79% to 91% for TSS. The single pond was less effective at removing pollutants and discharged water much faster after storm events than the pond in the series.

Drescher, S.R., Messersmith, M.J., Sanger, D.M., and B.C. Davis. 2007. Final report for two OCRM studies: stormwater pond baseline and efficiency

The stormwater pond baseline study conducted by SCDHEC-OCRM was finalized. Nutrient concentrations in the stormwater ponds were low (TN <1 mgL-1 and TP <0.09 mg L-1), however high chlorophyll levels indicated nutrients were entering the system. Water samples screened for algal composition found most bloom species to be cyanobacteria, with the genera Aphanizomenon, Microcystis, and Oscillatoria most frequently observed.

Ellis, K.C., Berg, C., Caraco, D., Drescher, S., Hoffmann, G., Keppler, B., LaRocco, M., and A. Turner. 2014. Low impact development in coastal South Carolina: a planning and design guide. ACE Basin and North Inlet-Winyah Bay National Estuarine Research Reserves, 462 pp.

Chapter Four of the LID guide provides information on stormwater best management practices, specifically wet detention ponds.  Information is provided on numerous topics including pond feasibility criteria such as soils, drainage area, depth to water table, and community and environmental concerns. Common concerns that are addressed include pollutants, mosquitoes, geese, and waterfowl. Design criteria are also discussed including forebay characteristics, pond geometry, stormwater pond benches, and proper sizing.  Ellis et al. (2014) details pond construction sequence, maintenance criteria, and additional resources for pond managers and community members. 

Failey, E. L., McCoy, J. C., Price, S. J., and M.E. Dorcas. 2007. Ecology of turtles inhabiting golf course and farm ponds in the western Piedmont of North Carolina. Journal of North Carolina Academy of Science 123: 221-232.

Golf courses and agricultural lands are a major form of anthropogenic habitat modification.  When properly designed and managed, they can also provide habitat for wildlife species.  This study examines the semi-aquatic turtle population inhabiting golf course and farm ponds to assess relative abundances and species richness, size distribution between sex and pond type, turtle body condition, sex ratio, and the effects of surrounding habitat and pond size on turtle abundance and richness. Failey et al. (2007) surveyed five golf course ponds and five farm ponds in western North Carolina.  418 individual turtles were captured representing six different species.  Species composition was similar among the two pond types, however relative abundance varied.  They found no significant difference in sex ratios except for the species Trachemys scripta, with a female biased sex ratio in golf course ponds. Results also found that relative abundances were positively correlated with pond area.  This study confirms that these two pond types (golf course and farm) can provide suitable habitat for several turtle species within the Piedmont region of NC.

Failey, S. M., Price, S. J., and M.E. Dorcas. 2012. Nest-site selection and nest depredation of semi-aquatic turtles on golf courses. Urban Ecosystems 15(2): 489-497.

Golf course ponds may serve as suitable turtle habitat in urbanized environments due to their large open, grassy habitat, however they often experience disturbances such as recurring human presence, frequent mowing, and pesticide/herbicide use.  This study examined nest site selection of painted turtles inhabiting a golf course pond in Davidson, NC. The effects of pond type and distance from pond edge on depredation rates were also investigated by simulating turtle nests at nine different ponds (three urban ponds, three golf course ponds, three farm ponds).  This study found that the painted turtles selected mulched locations to nest, and that areas impacted by anthropogenic uses (i.e., greens, sidewalks) were avoided.  Overall depredation rate was 38%, similar to results seen in other studies, and no difference in depredation rates among pond types was found.

Greenfield, D.I., Jones, W.J., Hogan. S., and C. Keppler. 2013. Elucidating the genetic diversity of Microcystis aeuruginosa within a toxic bloom in South Carolina coastal ponds using 454-pyrosequencing technology. [Abstract]. Seventh Symposium on Harmful Algae in the U.S. Sarasota, FL.

S.C. detention ponds accumulate nutrients and fertilizers and, when combined with poor flushing, are particularly susceptible to eutrophication and HABs. Microcystis aeuruginosa is the most abundant cyanobacteria HAB species. Greenfield et al. (2013) evaluated the spatial and genetic diversity of a key gene critical for the production of the hepatoxin microcystin within a particularly dense cyanobacteria bloom that occurred August-September of 2011. Initial results revealed multiple and distinct clades suggesting high intraspecific variability. 

Greenfield, D., Keppler, C., Hilborn, E., Gooch Moore, J., and P. Sandifer. 2014. Linking phytoplankton community composition with incidences of vibrio in stormwater detention ponds. [Abstract]. South Carolina Water Resources Conference, Columbia, S.C.

Evidence suggests linkages between the occurrence and distribution of harmful algal blooms (HABs) and the pathogenic Vibrio bacteria. Greenfield et al. (2014) collected water samples twice per month from two stormwater detention ponds and receiving tidal creeks to explore the relationship between water temperature, nutrient concentrations, algal blooms, and other factors. Results confirmed the presence of Vibrio species in 28% of the samples and several algal blooms.

Greenfield, D., Duquette, A., Goodson, A., Keppler, C., Williams, S., Brock, L., & … S. Wilde. 2014. The effects of three chemical algaecides on cell numbers and toxin content of the cyanobacteria Microcystis aeruginosa and Anabaenopsis sp. Environmental Management 54(5): 1110-1120

Cyanobacteria are responsible for the largest number of HABS in freshwater systems and are becoming increasingly common in brackish and coastal waterbodies as well. The cyanobacteria species Microcystis, Anabaenopsis, Oscillatoria, Nostoc, and Planktothrix produce microcystins, which are a group of hepatotoxins known to induce gastroenteritis, liver failure, and even death. Cyanobacteria blooms are often associated with high nutrient levels and warm, stagnant water conditions, making stormwater ponds the site of frequent cyanobacteria HABs. One management technique implemented to control cyanobacteria blooms includes applying copper sulfate, a commercial algaecide. While cyanobacteria are particularly sensitive to this compound, high levels of copper can have detrimental effects on the aquatic ecosystem. Hydrogen peroxide is used as an alternative. Greenfield et al. (2014) evaluated the ability of three algaecides for controlling cyanobacteria concentrations and microcystin levels.

Sampling took place at Kiawah Island pond K093. DO fluctuated between 1.65 mg L-1 to 16.28 mg L-1 over the sampling period. Nutrient analysis found the dissolved inorganic nitrogen pool to be primarily consisted of ammonium with levels ranging between 1.36 and 4.73 uM. Mean concentrations of DOP were 1-2 orders of magnitude greater than DIN with levels ranging from 2.57 to 23.13 uM. DIN: DIP levels were well below Redfield ratio, ranging between 0.19 and 1.80, indicating high phosphorous inputs. Phytoplankton blooms of Anabaenopsis sp. and Protoperidinium qinquecorne were observed during the study, and chlorophyll levels peaked from July 21-30. The algaecides used in the experiments were effective in controlling cell concentrations but did not reduce overall toxin levels. Microcystin levels increased over the course of the study compared to initial levels. The two copper sulfate-based algaecides resulted in the greatest reduction of cyanobacteria biomass.

Greenfield, D.I., Keppler, C., Brock, L., Reed, M., Kacenas, S., Hogan, S., and R. Van Dolah (2012). Assessing biological responses to nitrogen and phosphorous levels across the South Carolina coast [Abstract]. South Carolina Water Resources Conference, Columbia, S.C.

Numeric criteria for total nitrogen and phosphorous are lacking for S.C. estuarine and coastal systems. Biological responses should be considered in the development of these standards. Greenfield et al. (2012) assessed phytoplankton responses to N and P conditions in S.C. coastal and estuarine systems using a combination of field monitoring, in situ experiments, and laboratory studies.  Initial results found a high degree of spatial variability with respect to total nutrients. Phytoplankton assemblage responses were evaluated using nutrient addition bioassays at four sites characterized by distinct land cover patterns and presumably nutrient concentrations: the ACE Basin, Kiawah Island, Charleston Harbor, and Winyah Bay. Initial observations reveal N form strongly influences phytoplankton biomass and community composition, with organic and certain forms of inorganic N being primary drivers, and that biological responses display temporal and spatial variability.

Gingrich, J. B., Anderson, R. D., Williams, G. M., O’Connor, L., & K. Harkins. 2006. Stormwater ponds, constructed wetlands, and other best management practices as potential breeding sites for West Nile virus vectors in Delaware during 2004. Journal of the American Mosquito Control Association 22(2): 282-291.

Gingrich et al. (2006) compared mosquito vector production and larval abundance at five different types of BMPs in Delaware to determine their mosquito production potential. Of the BMPs sampled, 87 were stormwater ponds.  Perimeter and structural surveys to locate mosquito activity were conducted and mosquito larvae were collected biweekly from each site. Gingrich et al. (2006) found that detention ponds produced more mosquito larvae per dip than any other BMP, and that retention ponds produced peak numbers in August. When looking at species composition, Culex p. pipens, the most important West Nile vector, was far more abundant in retention ponds than any other BMP.

Guinn, G.C., Counts, K.A., Keppler, B., A. Turner. 2014. A 6,000 stormwater pond task: meeting the needs of diverse audiences for stormwater pond management outreach in the Berkeley, Charleston, and Dorchester communities [Abstract]. South Carolina Water Resources Conference, Columbia, S.C.

Stormwater ponds are a widely constructed BMP in coastal South Carolina, with over 6,000 ponds in the Berkeley, Charleston, and Dorchester (BCD) counties. Input from BCD counties has shown that stormwater managers need additional information regarding proper pond maintenance to improve pond function and protect downstream waterways. Guinn et al. (2014) details the results from the 2012 and 2014 Charleston Area Stormwater Pond Management Conference that was held to increase awareness of pond usage and maintenance, to provide participants with information needed to overcome challenges in pond management, and to integrate communities with service providers.

Halfacre, A., Hitchcock, D.R., and J.A. Shuler. 2007. Community associations and stormwater management: A coastal South Carolina perspective. Water Quality Improvement and Community Enhancement Series, Urbanization and Southeastern Estuarine Systems (USES) Project, 78 pp.

Population growth is expanding at a rapid rate in coastal S.C. Water is a key resource, vital for the health of coastal communities, and sustains important recreational activities. This report is an outreach document that provides insight for communities seeking to devise strategies to protect surrounding environmental resources. Successful pond management depends upon effective communication and successful implement of pond management strategies. Additionally, this document provides information essential to maintaining pond health, including mowing and landscaping activities, aeration strategies, herbicide application, fish stocking, and dredging.

Hancock, G. S., Holley, J. W., and R.M. Chambers 2010. A field‐based evaluation of wet retention ponds: how effective are ponds at water quantity control?  Journal of the American Water Resources Association 46(6): 1145-1158.

Hancock et al. (2010) evaluated pond performance by making direct measurements of pond inflow and outflow and comparing field data to original engineering designs in site stormwater management plans (SWMPs) and state and local regulations. The study took place in five residential stormwater ponds in James City County, Virginia. State regulations require wet retention ponds to retain inflow for 24 hours during the one-year, 24-hour storm, and to reduce the post-development offsite discharge by a two-year, 24-hour design storm to the pre-development offsite peak. Hancock et al. (2010) found that flows in and out of the ponds frequently exceeded the flows provided in the SWMPs. When examining lag or retention time, only one of the five ponds retained inflow for the required 24 hours, while the maximum retention time for the other four ponds was only 14 hours. They concluded that these ponds were not effectively designed to achieve the 24-hour retention time due to a simplified method to calculate pond size and diameter. As a result, the wet retention ponds did not provide downstream channel protection and instead had relatively high outflow and total runoff volume.

Hathaway, J.M., and W.F. Hunt. 2012. Indicator bacteria performance of storm water control measures in Wilmington, North Carolina. Journal of Irrigation and Drainage Engineering. 138(2): 185-197.

Stormwater runoff is a major source of indicator bacteria pollution, and the efficacy of stormwater control measures (SCMs) in reducing these pollutants remains largely unclear. Soil type (i.e., clay, sand) may play a role in removal efficiency, as microbes often attach to sediment particles and may persist for longer periods of time. How season and temperature affect SCM efficiency and bacteria concentrations is also unknown, but studies have shown concentrations to be highest in the warmer months. The objectives of this study were to evaluate the performance of SCMs in coastal watersheds for E. coli and enterococci and evaluate the influence of seasonality. Six SCMs were evaluated (two wet ponds, two bioretention areas, two stormwater wetlands) in Wilmington, NC from January 2008 to February 2010. Grab samples were collected from the inlet and outlet of the two wet ponds during each storm event (~15-20). Hathaway and Hunt (2012) found the highest concentrations of E. coli in the wet ponds, along with the highest reductions. The wet ponds were the only SCM that significantly reduced both E. coli and enterococci. The median effluent concentrations for E. coli at these sites were less than the U.S. EPA target values, while the concentrations for enterococci exceeded these values at all SCMs. Seasonality was examined in terms of swimming and non-swimming periods in order to capture the time of the year when humans were potentially exposed during recreational activities. While there were differences in inlet and outlet concentrations between swimming and non-swimming periods, they were not statistically significant. Further research is needed to understand the mechanisms involved in indicator bacterial removal in SCMs.

Hathaway, J. M., Hunt, W. F., & S. Jadlocki. 2009. Indicator bacteria removal in storm-water best management practices in Charlotte, North Carolina. Journal of Environmental Engineering 135(12): 1275-1285.

Indicator bacteria such as total coliform, fecal coliform, E. coli, and enterococci, have been used to assess water quality degradation due to pathogens. Stormwater runoff from urbanized areas can increase indicator bacteria concentrations in nearby surface waters, posing a risk to human health. Hathaway et al. (2009) investigated which stormwater BMPs were capable of efficient indicator bacteria reduction. 12 stormwater BMPs were examined in the Charlotte-Mecklenburg area, including one pond that was not originally constructed for stormwater purposes but was retrofitted in the 90s to include a littoral shelf.  Hathaway et al. (2009) found that the wet pond removed greater than 50% of fecal coliform bacteria and around 46% of E. Coli.  However, the effluent concentrations were still well above the EPA target values for fecal coliform (200/100 mL) and E. coli (126/100 mL). While stormwater BMPs can reduce bacteria levels, they can also potentially be sources of indicator bacteria.

Hayes, K.C., and A.J. Lewitus. 2004. A eutrophic assessment of lagoonal pond systems in South Carolina coastal waters: have we overlooked their impact on coastal development [Abstract]. ASLO, Savannah, GA.

Results from nutrient, chlorophyll, and phytoplankton monitoring of lagoonal pond systems found hypereutrophic conditions during the summer and high nutrient concentrations throughout the year. Chlorophyll levels were high in the fall, winter, and spring, with harmful algal blooms present and increasing from spring to fall. With the frequent tidal exchange between ponds and estuarine systems, it is important to include stormwater ponds when assessing the effects population growth and coastal development have on the health of tidal ecosystems.

Hayes, K.C., Lewitus, A.J., and S.B. Wilde. 2008. Seasonal variations in phytoplankton growth and microzooplankton grazing in a eutrophic coastal lagoonal system in South Carolina [Abstract]. Ocean Sciences Meeting, Orlando, FL.

Hayes et al. (2008) evaluated the importance of grazing on controlling bloom formation and bloom decline. A dilution experiment was conducted in 2006-2007 in two stormwater detention ponds. Phytoplankton growth varied seasonally. Microzooplankton grazing consumed on average >80% of production and could potentially play an important role in reducing phytoplankton productivity and export to adjacent water bodies.

Hehman, L. 2014. The effects of aeration on phytoplankton community composition and primary production in stormwater detention ponds near Myrtle Beach, S.C. MS Thesis, University of South Carolina, Columbia, S.C.

Hehman (2014) tested the effects of aerators on DO levels, nutrient concentrations, and phytoplankton biomass/composition in a pair of ponds from two residential communities in Myrtle Beach, S.C. The first year of the study before installation took place, thermal stratification occurred in all four of the ponds. Bottom DO concentrations were lower and significantly different than surface concentrations at all ponds and often reached levels of hypoxia during the summer months. After installation, bottom DO concentrations increased in two of the ponds (SBA and IOA), however DO levels remained low in the other two ponds (SBB and IOB). Overall, there was no reduction in nutrient concentrations, rates of PP, or phytoplankton biomass/composition after aerator installation.

Holland, A. F., D. M. Sanger, C. P. Gawl, S. B. Lerberg, M. S. Santiago, G. H. M. Riekerk, L. E. Zimmerman, and G. I. Scott. 2004. Linkages between tidal creek ecosystems and the landscape and demographic attributes of their watersheds. Journal of Experimental Marine Biology and Ecology 298:151-178.

Within the southeast, human population growth is expected to increase rapidly, leading to increased development with the construction of residential communities, commercial buildings, and industrial sites. For instance, between 1973 and 1994 Charleston, S.C.’s population increased by 40% while its urban area increased by roughly 250%. Expanding development results in land cover alterations (i.e., greater amounts of impervious surface), which negatively affects biodiversity and the ecological functioning of coastal and aquatic systems. It has been shown that when percent impervious surface cover reaches around 30% of the watershed, severe biological degradation occurs. Holland et al. (2004) reviews the relationship of development, primarily as impervious surface cover, to chemical and physical exposures and the biological responses.

Holt, C.B., Gould, W.J., McSorley, A.J., Oakley, W.F., Overcash, J.M., and M.H. Watson. 2015. Daimler stormwater pond survey-Spring 2015. The Citadel, Charleston, S.C.

The Citadel’s Department of Biology conducted a survey of three stormwater ponds on Daimler Vans Manufacturing property in Ladson, S.C. Water quality, water level, faunal diversity, and floral diversity was assessed. Results from the survey found that one of the ponds exceeded the acceptable range for pH (6.0-9.0). The faunal survey found frog eggs and a green tree frog at the site along with three reptile species, a dozen bird species, two fish species, 14 arthropod species, two mammal species, one annelid species, two mollusk species, two amphibian species, and five distinct microorganisms. Overall plant species richness across the three ponds was 34. A single plant of the non-native Japanese climbing fern (Lygodium japonicum) was also observed.

Horgan, F. G., Stuart, A. M., and E.P. Kudavidanage. 2014. Impact of invasive apple snails on the functioning and services of natural and managed wetlands. Acta Oecologica 54: 90-100.

Fourteen species of apple snails have been released outside of their native range.  Horgan et al. (2014) reviewed the impacts of apple snails on natural and managed wetlands. Pomacea maculata, native to Florida and Cuba, has been documented in Alabama, North Carolina, and Puerto Rico. Apple snails display selective herbivory feeding on macrophytes with low chemical and structural defenses. For example, P. maculata was found to be more abundant on alligator weed in artificial ponds in Texas.  Due to intense grazing pressures, they have the potential to shift the composition of macrophyte communities and potentially cause a shift in nutrient cycling that can lead to a plankton-dominated state. Apple snails have also been shown to adversely affect the population of other benthic organisms, particularly other aquatic snails, due to predation.

Huda, M.K., and M.E. Meadows. 2010. Critical assessment of management practices and policies for stormwater and sediment ponds in South Carolina. [Abstract]. 2010 South Carolina Water Resources Conference, Columbia, S.C.

Huda and Meadows (2010) conducted a parametric study to analyze pond performance for varying storm events focusing on return period, rainfall depths, and duration. Runoff hydrographs were simulated using the SC synthetic Unit Hydrograph Method and modeled conditions pre-development, post-development and during the construction phase for a watershed in Richland County, S.C. The computer program used for this study was Drain: Hydro 2.0. Comparing a stormwater detention pond and a sediment retention pond, they found the retention pond provided better channel protection and sediment trapping efficiency. Additionally they found that retention ponds can maintain post-development hydrograph shape, volume, timing, and sediment transport capacity at pre-development levels.

Hunt, W. F., Apperson, C. S., Kennedy, S. G., Harrison, B. A., and W.G. Lord. 2005. Occurrence and relative abundance of mosquitoes in stormwater retention facilities in North Carolina, USA. [Abstract]. Water Science and Technology 54(6-7): 315-321.

Hunt et al. (2005) sampled 52 stormwater retention facilities (i.e., standard wet pond, innovative pond, wetland pond). Fourteen different species of mosquitoes were collected from 34% of the structures and seasonal prevalence, and relative abundance of mosquitoes did not vary among structures. Additionally, a significant relationship between the presence of mosquitoes and the absence of mosquitofish was found for the innovative and wetland pond, which was not observed in the standard wet pond.

Johnston, M. A., Porter, D. E., Scott, G. I., Rhodes, W. E., and L.F. Webster. 2010. Isolation of faecal coliform bacteria from the American alligator (Alligator mississippiensis). Journal of Applied Microbiology 108(3): 965-973.

Johnston et al. (2010) provided evidence that stormwater ponds are important habitats for the American alligator. This study found that the American alligator is a source of fecal coliform in stormwater ponds resulting in elevated FCB concentrations and water quality impairment. One golf course pond sampled exceeded the recreational criteria <200 CFU 100 ml-1, by containing 2600 CFU 100 ml-1.

Jones, M.P., and W.F. Hunt. 2010. Effecet of storm-water wetlands and wet ponds on runoff temperature in trout sensitive waters. Journal of Irrigation and Drainage Engineering. 136(9): 656-661.

In the summer, stormwater runoff that occurs over pavement can have elevated temperatures due to heat transfer from the surface. This water is then discharged into adjacent creeks,, where thermal pollution can negatively affect temperature sensitive species such as trout and salmon. It has been found that stormwater ponds can exacerbate this problem, producing effluent temperatures that can even be higher than the influent temperatures, likely due to a lack of shading around the pond. Temperature, flow, and rainfall were monitored in a stormwater wetland and wet pond in Asheville and Lenoir, North Carolina, respectively. Jones and Hunt (2010) found that the median pond effluent was significantly higher than the water entering the pond inlets, indicating it could be a source of thermal pollution. The effluent from the pond was also significantly warmer than the effluent from the stormwater wetland from June to September. The data also found stratification occurring within the pond as temperatures at the depths 0, 20, 80, and 120 cm were all different from each other. A modified outlet pulling water from the bottom of the pond could be beneficial.

Kempton, J. W., Lewitus, A. J., Deeds, J. R., Law, J. M., and A.R. Place. 2002. Toxicity of Karlodinium micrum (Dinophyceae) associated with a fish kill in a South Carolina brackish retention pond. Harmful Algae 1(2): 233-241.

Blooms of the dinoflagellate Karlodinium micrum have been associated with fish kills, and K. micrum cultures have been shown to have toxic effects on mussels and juvenile cod. On February 5, 2000, a fish kill in a Mount Pleasant, S.C. retention pond was reported, and upon further analysis of collected water, a high concentration of the dinoflagellate K. micrum was found. On February 5-6, DO concentrations ranged from 10.1 to 14.6 mg L-1. Nutrient conditions during the time of the bloom/fish kill indicate higher ammonium levels than nitrate/nitrate levels, high DOC and DON, and a Redfield Ratio of 1.7± 0.3. Chlorophyll levels were high, with mean values of 117 ± 15 ug ml-1. K. micrum identification was molecularly confirmed through real-time PCR. Results from this study provide evidence that links harmful algal blooms with fish kill events.

Kempton, J. W., Wolny, J., Tengs, T., Rizzo, P., Morris, R., Tunnell, J., Scott, P., Steindinger, K., Hymel, S.N., and A.J. Lewitus. 2002. Kryptoperidinium foliaceum blooms in South Carolina: a multi-analytical approach to identification. Harmful Algae 1(4): 383-392.

Kempton et al. (2002) reevaluated species identification within the genus Kryptoperidinium, focusing on morphological and molecular taxonomic characteristics. Four K. foliaceum cultures were compared to a S.C. K. foliaceum isolate and environmental field samples. Kempton et al. (2002) found that environmental samples from a brackish retention pond on Hilton Head Island, which appeared similar to K. foliaceum under light microscopy, did not amplify with K. foliaceum specific primers. Additionally they found an absence of the endosymbiont nucleus from the S.C. K. foliaceum isolate that was not seen in culture.

Keppler, C. J., Lewitus, A. J., Ringwood, A. H., Hoguet, J., and T. Staton. 2006. Sublethal cellular effects of short-term raphidophyte and brevetoxin exposures on the eastern oyster Crassostrea virginica. Marine Ecology Progress Series 312: 141-147.

The raphidophytes Chattonella subsalsa, C. cf. verruculosa, F. japonica, and H. akashiwo have recently been associated with fish mortalities in several South Carolina brackish, stormwater-detention ponds.  While there is cumulative evidence for the impacts of raphidophyte blooms on finfish populations, less is known about their impacts on shellfish. Keppler et al. (2006) examined the sublethal cellular effects of purified brevetoxin and raphidophyte bloom (C. subsalsa, F. japonica) exposure on oysters. Bloom water was collected from two stormwater detention ponds on Kiawah Island, and oysters were placed into control seawater and bloom water treatments for a 96-hour period. Oysters were also placed in control seawater and purified brevetoxin treatments. The brevetoxin (PbTx-3) was added at the concentrations 0.1, 1.0, and 10 nM. At the end of each experiment, the oyster’s digestive gland tissue was dissected out for lysosomal destabilization analysis and the remaining was frozen for lipid peroxidation and glutathione concentration analysis. Keppler et al. (2006) found a significant increase in lysosomal destabilization following exposure to bloom water. Lysosomal destabilization also significantly increased in oysters exposed for 72 hours to 1 and 10 nM PbTx-3. These results suggest that one mechanism of raphidophyte toxicity is brevetoxin production.

Koch, B. J., Febria, C. M., Gevrey, M., Wainger, L. A., and M. A. Palmer. 2014. Nitogen removal by stormwater management structures: a data synthesis. Journal of the American Water Resources Association 50(6): 1594-1607.

Koch et al. (2014) conducted a literature search for detention/retention ponds, constructed wetlands, and vegetated swales to analyze N removal rates between these stormwater pond structures. They hypothesized that N removal would vary as a result of watershed features and hydrologic factors. They found 325 observations of N removal in urban and suburban watersheds from 30 studies, and chose to focus on removal rates of NH4, NO3 and TN. From the data they selected, they concluded that these three BMPs were effective at removing N, but performance was highly variable. Removal efficiencies ranged from negative values to 100%. More specifically, they found deeper ponds did not remove NH4 as effectively as shallower ponds, and ponds with larger volumes didn’t perform as well as smaller ones. This suggests that BMP size could influence efficiency rates, as well as pond age and position in the watershed. Koch et al. (2014) stresses the need for long-term monitoring of stormwater BMPS.

Krometis, L.H., Drummey, P.N., Characklis, G.W., and M.D. Sobsey. 2009. Impact of microbial partitioning on wet retention pond effectiveness. Journal of Environmental Engineering 135(9): 758-767.

Fecal indicator organisms have been identified as a leading cause of water quality impairment, and sedimentation-based BMPs such as wet detention ponds are commonly used to remove these microbial contaminants. The mechanisms of microbial removal are poorly understood. This study examines microbial partitioning to determine where microbial-particle association occurs in the transport chain and whether wet ponds are effective at removing bacteria through sedimentation. Two ponds located in a suburban development in the Northeast Creek watershed in North Carolina were selected as the study site along with two downstream points in Northeast Creek. Samples were collected during storm and dry weather conditions. Results from this study found that microbe-particle association occurred near the upland sources and that microbial concentrations were higher at the upland residential areas than downstream in the creek. The effectiveness of the wet ponds at removing bacteria was mixed, and in some cases the ponds acted as a source for downstream microbial loading.  While fecal coliform and E. coli concentrations were reduced, enterococci levels were sometimes higher in the outflow of the ponds.

Lewitus, A. J., and A.F. Holland. 2003. Initial results from a multi-institutional collaboration to monitor harmful algal blooms in South Carolina. Environmental Monitoring and Assessment 81(1-3): 361-371.

Prior to 1988 there was only one documented instance of a HAB in S.C. coastal waters. This was likely attributed to low development along the coast and the high flushing capabilities of S.C. estuarine systems. The S.C. Task Group on Harmful Algae was formed in 1997 to monitor Pfiesteria-related events and has since been extended with the formation of the S.C. Harmful Algal Bloom Program focusing on monitoring, event response, nutrient response bioassays, and outreach.  Lewitus and Holland (2003) summarized the documentation of HABs over a three year period.

On March 30, 2001 a fish kill was reported in a seven-acre brackish pond on Hilton Head, and water samples from the site contained Pfiesteria-like organisms (PLOs). Two brackish ponds on Kiawah Island were also found to contain PLOs, one with potentially toxic densities, indicating that brackish ponds may be vulnerable to toxic Pfiesteria. During the spring of 1998, the first red tide bloom was documented in S.C. estuarine waters and was attributed to Kryptoperidinium sp. Monospecific populations of this species were also observed in the spring of 2001 in S.C. estuaries where it was previously not known to occur. The blooms that occurred at these two sites were succeeded by a Heterosigma akashiwo bloom followed by a Chattonella verruculosa and C. subsalsa bloom on Hilton Head and a Chattonella verruculosa bloom followed by a C. subsalsa bloom on Kiawah. Following the C. subsalsa bloom, both residential ponds reached high densities of Fibrocapsa japonica. The increasing number of HABs in S.C. water bodies is likely a result of increased anthropogenic nutrient loading due to rapid population growth along the coast.

Lewitus, A., Hayes, K., Kempton, J., Mason, L., Wilde, S., Williams, B., and J. Wolny. 2004. Prevalence of raphidophyte blooms in South Carolina brackish ponds associated with housing and golf courses. In: K. Steindinger, Landsberg, J.H., Tomas, C.R., and G.A. Vargo (eds) Harmful Algae. UNESCO, St. Petersburg, FL, p 350-352.

Lewitus et al. (2004) documented the abundance and distribution of raphidophytes within brackish lagoonal ponds. From April 2001 to November 2002, 40 brackish/marine stormwater ponds were sampled primarily on Kiawah Island, Hilton Head Island, and in the Charleston area. Of the 528 samples collected, raphidophytes were confirmed in 47% and were more commonly observed when salinities exceed 9 0/00. There was also a notable seasonal trend, with raphidophytes occurring in 66% of the samples from April through August and only in one of the 22 samples collected from November to February. The four raphidophyte species identified were Heterosigma akashiwo, Chattonella subsalsa, C. verruculosa, and Fibrocapsa japonica. Nutrient analysis found mean orthophosphate concentration to be 9.7 ±7.1 um with a mean DIN: DIP ratio of 0.72, indicating high phosphorous inputs. Mean DOC (1213±584 uM) and DON (60±20uM) concentrations were relatively high as well. Due to their association with fish kills and prevalence within S.C. brackish ponds, raphidophytes are becoming a globally growing concern.

Lewitus, A. J., Schmidt, L. B., Mason, L. J., Kempton, J. W., Wilde, S. B., Wolny, J. L., Williams, B.J., Hayes, K.C., Hymel, S.N., Keppler, C.J., and A.H. Ringwood. 2003. Harmful algal blooms in South Carolina residential and golf course ponds. Population and Environment 24(5): 387-413.

Stormwater ponds may be contributing to the degradation of aquatic ecosystems by acting as “incubators” for estuarine microorganisms, particularly HABs. Lewitus et al. (2003) provides an update on HAB documentation within S.C. ponds. Sampling in 2001 took place on Hilton Head and Kiawah Island. HABS were comprised of PLOs, H. akashiwo, C. verruculosa, C. subsalsa, F. japonica, P. parvum, and Kryptoperidinium sp. species. None of the HABs besides Kryptoperidinium sp. had ever been reported in S.C. waters. A F. japonica bloom occurred in a Kiawah Island pond and two days later was detected in an adjacent creek, suggesting transport during tidal exchange. Nutrient concentrations revealed NH4+ as being the predominant DIN compound and relatively high PO4 concentrations, resulting in a DIN: DIP ratio well below Redfield Ratio. 22 fish kills were documented in S.C. brackish-marine waters from 2001 to 2002, six of which were associated with high HAB species abundances and DO concentrations, although it is difficult to establish causation. Blooms often coincide with high levels of PO4, DOC, and DON. The high DON and low DIN concentrations could give certain species capable of utilizing organic nitrogen a competitive advantage within these ponds. Further research and information is needed to understand bloom dynamics and the environmental factors that regulate and maintain blooms.

Lewitus, A. J., Brock, L. M., Burke, M. K., DeMattio, K. A., and S.B. Wilde. 2008. Lagoonal stormwater detention ponds as promoters of harmful algal blooms and eutrophication along the South Carolina coast. Harmful Algae 8(1): 60-65.

Monitoring efforts by the S.C. Algal Ecology Laboratory from 2001 to 2005 revealed a high abundance of raphidophytes in brackish lagoonal ponds (40% of 1,502 ponds sampled). HAB type is closely related to salinity, with dinoflagellate and raphidophyte blooms occurring most frequently in mid-brackish to marine conditions and cyanobacteria occurring in low brackish waters. Data collected from SCAEL long-term monitoring indicates that eutrophic systems are local sources for HABS and that many of these blooms are associated with toxins, fish kills, and shellfish health effects. Due to their tidal exchange with adjacent estuaries, these ponds are capable of exporting nutrients into primarily nitrogen-limited coastal water bodies. Mitigation efforts are being explored, such as the addition of constructed wetlands to supplement stormwater ponds. Constructed wetlands enhance stormwater and groundwater processing, mimicking a natural systems, and can help restore denitrification processes and nutrient uptake.

Liu, J., Lewitus, A. J., Kempton, J. W., and S.B. Wilde. 2008. The association of algicidal bacteria and raphidophyte blooms in South Carolina brackish detention ponds. Harmful Algae 7(2): 184-193.

Numerous raphidophyte blooms have occurred over the past five years within S.C. coastal waters, particularly stormwater detention ponds. With the lack of studies examining the dynamics of HABs and algicidal microorganisms, Lie et al. (2008) investigated the relationship algicidal microorganisms have with the three raphidophytes: Heterosigma akashiwo, Chattonella subsalsa, and Fibrocapsa japonica. The study took place in three Kiawah Island brackish detention ponds from 2002-2004. In seven of nine observations, Liu et al. 2008 found that bloom formation coincided with an increase of algicidal bacteria that was capable of lysing or inhibiting growth of the raphidophytes. Rapid bloom termination often followed an increase in algicidal bacteria, however this was not always the case. H. akashiwo and C. subsalsa were more sensitive to the bacteria isolates than F. japonica, indicating that F. japonica may have a type of protective mechanism. This study provides evidence that algicidal bacteria may be able to provide top-down control of raphidophyte blooms in coastal ponds.

Mallin, M. A., Ensign, S. H., Wheeler, T. L., and D.B. Mayes. 2002. Pollutant removal efficacy of three wet detention ponds. Journal of Environmental Quality 31(2): 654-660.

Wet ponds are designed primarily to reduce suspended sediments but can effectively reduce concentrations of other pollutants such as nutrients, fecal bacteria, and heavy metals. Mallin et al. (2002) analyzed three wet detention ponds for pollutant removal performances in Wilmington NC. The three ponds, Ann McCrary, Silver Stream, and Echo Farms Country Club pond, varied in vegetation type and coverage, pond geometry and post-treatment. Sampling occurred monthly from October 1997 to February 2000. Chlorophyll, fecal coliform, nutrients, TSS,and pollutant metals in sediments were measured. The three ponds displayed mixed results. The highest degree of success was at Silver Stream pond, where inorganic nutrients showed high removal rates. Within Echo Farms, they found increases in outflow pollutants compared to the inputs, likely attributable to runoff from the surrounding golf course. Mallin et al. (2002) also found a correlation between same day rainfall and fecal coliform, and cumulative rainfall and TSS and nutrients.

Massal, L. R., Snodgrass, J. W., and R.E. Casey. 2007. Nitrogen pollution of stormwater ponds: potential for toxic effects on amphibian embryos and larvae. Applied Herpetology 4(1): 19-29.

Massal et al. (2007) examined whether nitrogen levels could reach levels toxic to amphibian larvae in retention ponds. If so, these habitats could act as ecological traps for pond breeding amphibians if the larvae suffer high rates of mortality. Nitrate, nitrite, and ammonia concentrations were measured seasonally and following storm events alongside the occurrence of amphibians in stormwater basins in Baltimore County, MD. They found that nitrite and ammonia concentrations were not high enough to induce sublethal or lethal effects in amphibians. Nitrate was detected most often but did not appear to affect anuran population breeding at these basins. Overall, this watershed did not have elevated inorganic nitrogen concentrations. Additional studies are needed, and the lack of salamander use of stormwater ponds warrants further investigation.

Mark Messersmith. 2007. Assessing the hydrology and pollutant removal efficiencies of wet detention ponds in South Carolina. MES Thesis, College of Charleston, Charleston, S.C.

Moore, P.R. 2010. Retrofitting regional stormwater quality BMPs for bacteria treatment and volume control in Beaufort County. [Abstract]. South Carolina Water Resources Conference, Columbia, S.C.

Beaufort County commissioned a stormwater study and identified basins with high measured and predicted fecal coliform loads. To address the water quality issues, Beaufort County implemented a plan to retrofit 10 basins. Data collected upstream and downstream of stormwater control ponds has found that when properly maintained these ponds are effective at treating stormwater for bacteria removal. However, many of the rivers in developing areas are still degrading. High fecal coliform levels tend to occur with lower salinities, and it is believed that development has caused high volumes of freshwater to be discharged into these water bodies, decreasing salinity and increasing the frequency of high bacterial counts. Traditionally designed detention ponds may not be adequately handling smaller, more frequent rain events. The retrofit plan includes adding a vegetated flood shelf as a volume control design feature to a current storm water pond that is able to handle 95th percentile rain events.

Moore, T. L., and W.F. Hunt. 2012. Ecosystem service provision by stormwater wetlands and ponds–A means for evaluation? Water research 46(20): 6811-6823.

Ponds, constructed stormwater wetlands (CSWs), and other stormwater control measures (SCMs) are usually evaluated for hydrological performance and pollutant removal efficiency. The objective of this study was to assess and compare a range of additional ecosystem services provided by stormwater ponds and CSWs, focusing on biodiversity, cultural service provisions, and carbon sequestration. They chose 20 CSWs and 20 ponds across North Carolina, USA. They found a lack of carbon accumulation in non-vegetated ponds implying that autochthonous production was important within these systems. These results suggest that establishing dense emergent vegetation is important to carbon sequestration. Biodiversity was evaluated using vegetation and aquatic macroinvertebrate number and richness. Over 50 species of vegetation were observed in both SCMs. The only wetland plant more likely to occur in ponds was the exotic invasive species Ludwigia hexapetala. 31 macroinvertebrate families were observed in both systems, and mean macroinvertebrate richness of individual ponds was greater than the CSWs. They also found that mosquito larvae were more frequently observed in pond systems. Results from the biodiversity assessment stress the important of establishing emergent vegetation for attracting a diverse assemblage of insects.

Reed, M. 2014. The influence of macronutrient form on the spatial and seasonal variability of phytoplankton assemblages and bacteria abundances in four coastal South Carolina systems. MS Thesis, College of Charleston, Charleston, S.C.

Reed (2014) assessed phytoplankton biomass and community composition response to macronutrient form using in situ nutrient addition bioassays. Research was conducted at four tidally influenced sites characterized by distinct land-use patterns. Sites include Thousand Acres in Winyah Bay, Bull Creek in the Charleston Harbor, Wimbee Creek in the ACE Basin, and stormwater pond K075 on Kiawah Island. HABs have frequently been reported in S.C. stormwater detention ponds, and ponds on Kiawah Island are characterized as having high Chl a, N, and P concentrations. Land cover surrounding pond K075 was determined as open water (32%), emergent herbaceous/woody wetlands (31%), evergreen/deciduous/mixed forest (15%), and low intensity/open developed land (11%). Pond K075 exhibited low NO2 + NO3 and NH4+ concentrations, and high PO43– concentrations and TN:TP ratios were less than 16:1 across all bioassay experiments, ranging from 2.9 to 6.2. Reed (2014) found that phytoplankton composition responses were highly dependent on nutrient treatments. Additionally phytoplankton communities in relatively more developed sites such as pond K075 exhibited higher biomass, growth rates, and occurrences of HAB species in N addition treatments (i.e., urea) compared to phytoplankton communities in less developed sites. HAB species Pseudo-nitzschia sp., Heterosigma akashiwo, Heterocapsa rotundata, and Prorocentrum minimum were identified in samples from pond K075 throughout the experiment. Despite one bloom of Thalassiosira sp., the pond had relatively higher contribution of non-diatom taxa (i.e., cyanobacteria, prasinophytes, and dinoflagellates) compared to other sites. Results from this study indicate that urea-based fertilizers applied to the golf courses and lawns could increase the proliferation of HABs.

Reed, M.L., DiTullio, G.R., Kacenas, S.E., and D.I. Greenfield. 2015. Effects of nitrogen and dissolved organic carbon on microplankton abundances in four coastal South Carolina (USA) systems. Aquatic Microbial Ecology 76:1-14.

Reed et al. (2015) examined the seasonal levels of DOC, bacterial abundances, and phytoplankton biomass (chl a) across four coastal S.C. sites with distinct land uses, including stormwater pond K075 on Kiawah Island. Specific objectives included determining whether correlations existed between DOC concentrations, bacterial abundances, and chl a concentrations, and with environmental parameters. Additionally Reed et al. (2015) wanted to determine whether bacterial abundances and DOC responses corresponded with chl a changes in N and P addition bioassays that were conducted concurrently.

DOC was positively correlated with Chl a at the more developed sites, including pond K075, while bacterial abundances and chl a were negatively correlated. Overall, DOC, bacteria, and chl a concentrations were not significantly correlated with one another. However, elevated chl a levels were found in N addition treatments, particularly in the summer with additions of urea, at pond K075. High DOC concentrations in treatments containing urea suggest that the increase in phytoplankton biomass could be contributing to the total DOC pool. Changes in the contribution of phytoplankton biomass to the total DOC pool could affect biogeochemical cycling within these systems and warrants additional studies.

Rollins, S.C., Giacalone, K., Callahan, T.J, Levine, N.S., and L.S. Mills. 2012. Residential stormwater pond maintenance and outreach in the lowcountry. [Poster]. South Carolina Water Resources Conference, Columbia, S.C.

There are over 2.6 million retention and detention ponds nationally, 14,000 in coastal South Carolina, and around 6,000 ponds in the Berkeley, Charleston, and Dorchester (BCD) counties. Sediment and pollutants collected in runoff are deposited in stormwater ponds and can be filtered out through sedimentation before the water is drained intro nearby waterways. Rollins et al. (2012) details ongoing work to develop a comprehensive GIS-based inventory database of retention ponds in the BCD region to guide outreach efforts for pond owners and managers. A survey will be developed and conducted regarding stormwater pond maintenance, and a pond information booklet and maintenance log will be created for stormwater managers.

Sassard, A., DeVoe, R., Sheldon, S., Callahan, T., Greenfield, D., Hitchcock, D., Peterson, R., Smith, E., Turner, A., Weinstein, J., Sanger, D., and J. Allen. 2014. Facilitating stormwater pond research through collaboration [Poster]. South Carolina Water Resources Conference, Columbia, S.C.

Over 14,000 ponds are located in the coastal S.C. region and they are the most commonly used BMP for stormwater runoff control and increasingly to improve water quality. Sassard et al. (2014) provides information on S.C. Sea Grant Consortium’s plan to enhance multi-disciplinary research on stormwater pond-related projects. This collaborative effort will support the development of an ecological characterization of stormwater ponds to aid in the creation of an integrated and sustainable economic and natural resource strategy for continued construction and use of stormwater ponds.

Aquatic Nuisance Species Program: Invasive Island Apple Snail. 2012. South Carolina Department of Natural Resources. Retrieved from

SCDNR Aquatic Nuisance Division has discovered the invasive island apple snail Pomacea insularum in a retention pond southeast of Socastee, S.C. After the original siting, surveys of over 200 ponds in the surrounding area found 35 infested within a four-mile radius. The island apple snail is of particular concern due to its potential to cause a wide variety of negative impacts. They threaten S.C. aquatic ecosystems by destroying native plant species and out-competing native snail species. They can also act as vectors for diseases and parasites such as rat lungworm. SCDNR has created a map indicating where the snails have been located in Horry County.

Serrano, L., and M.E. DeLorenzo. 2008. Water quality and restoration in a coastal subdivision stormwater pond. Journal of Environmental Management 88:43-52.

Stormwater ponds receive runoff from urbanized areas, containing high levels of nonpoint source pollutants. These pollutants enter the pond systems and are removed from the water column through sedimentation or utilized in biological processes. Due to a combination of low circulation and high nutrient concentrations, stormwater ponds have elevated algal biomass that can lead to the formation of HABs. High fecal coliform bacteria and chemical contaminant levels have also been found in these systems. Serrano and DeLorenzo (2008) characterized water quality in stormwater pond Lake Edmund (LE) and the adjacent creek, Kushiwah Creek (KC) in James Island, S.C. Water quality analysis showed lowed DO concentrations during the summer for both LE and KC. All LE and KC samples exceeded the total phosphorous EPA guideline for lakes and reservoirs (0.024-0.048 mg/L) and estuarine waters. (0.1 mg/L) All chlorophyll samples collected from LE exceeded the EPA eutrophication standard of 4.1 ug/L established for lakes and reservoirs. High Chl a concentrations corresponded with dense algal blooms. There was a strong positive correlation found between chlorophyll levels and nitrate/nitrite concentrations in LE. LE was the site of a dense cyanobacteria blooms throughout the sampling period produced by Anabaena sp. and Microcystis sp., several of which produced high levels of microcystin. Cyanobacterial blooms seemed to occur when phosphorous levels were high. Anabeana sp. and Microsystis sp. were also detected in the estuary adjacent to LE in 39% of their samples collected during 2004 and 2005. 78% of these detections coincided with algal blooms in Lake Edmund, indicating export out of the pond to the tidal creek. The toxin microcystin was detected in samples from the creek and was also present within the pond. Fecal coliform bacteria levels were higher in KC than LE, which is similar to results from a study on Kiawah Island in which a downstream tidal creek had greater FC concentrations than the stormwater ponds. FC concentrations exceeded the 200 CFU/100mL standard in 33% (LE) and 73% (KC) of the months sampled.

Siegel, A., Cotti-Rausch, B., Greenfield, D. I., and J.L. Pinckney. 2011. Nutrient controls of planktonic cyanobacteria biomass in coastal stormwater detention ponds. Marine Ecology Progress Series 434: 15-27.

Prior to the 1970s there were only 15 natural ponds on Kiawah. Currently there are 136 ponds that account for 8.4% of the total land area on the island. 95% of these ponds are brackish to marine and are affected by high nutrient levels (N and P) due to runoff from golf courses, roadways, and residential lawns. It has been shown that these pond systems are limited by DIN,and therefore additions of N stimulate phytoplankton growth. Evidence also suggests that DON levels may be high in certain ponds and that urea may be an important component of the DON pool. Few studies have been conducted to examine the effects DIN in combination with DON have on cyanobacteria biomass, prompting Siegel et al. (2011) to quantify the response of cyanobacteria species to different forms and combinations of N (NO3-, NH4+, and DON as urea). Kiawah ponds K61 and K67 were chosen for the study.

Nutrient analysis found both ponds have high orthophosphate concentrations. Initial assessment of the phytoplankton community composition found diatoms, cyanobacteria, chlorophytes, euglenophytes, and prasinophytes to be common from June to September. Initial cyanobacteria biomass in pond K61 represented 6% of total chlorophyll levels in June and reached 36% in July. In pond K67, cyanobacteria accounted for 6% of the biomass in June and July and roughly 9% in August and September. Nutrient addition bioassays found that all four cyanobacteria genera increased in abundance in pond K61 and Microcystis, Anabaena, and Oscillatoria increased in pond K67. The urea, NO3, and NH4+ + urea additions resulted in the greatest increases in total chlorophyll in pond K61, while there was no significant difference for the N additions in pond K67. Focusing specifically on cyanobacteria, urea additions produced significantly higher biomass in K61, while NH4+ + urea and NH4+ additions produced the highest biomass in K67. This study provides evidence that DON in coastal stormwater ponds can act as an N source for cyanobacteria, and management strategies should target ways to reduce organic nitrogen.

Siewicki, T. C., Pullaro, T., Pan, W., McDaniel, S., Glenn, R., and J. Stewart. 2007. Models of total and presumed wildlife sources of fecal coliform bacteria in coastal ponds. Journal of environmental management 82(1): 120-132.

Stormwater ponds are designed to retain a certain volume of runoff to allow sediments to settle before being discharged in adjacent waterbodies. Removal efficiency is often complicated by timing of runoff and tidal exchange that occurs with adjacent estuaries during high tide. Land-use cover changes associated with development have dramatically altered the wildlife carrying capacity. Wildlife are a significant source of fecal coliform bacteria into water bodies, and high FCB levels are often found near areas of population growth and development, prompting the need to create a model to estimate bacterial loading into water bodies. Siewicki et al. (2007) developed a model for retention ponds where tidal exchange results in the twice daily loading of bacterial concentrations into estuaries.

Aerial photography from 1999 revealed that there were approximately 8,114 ponds located within the coastal zone of S.C. Six ponds were chosen for the study in three resort areas along the coast of South Carolina. Bacterial sources at these sites were primarily wildlife, pets, and effluent. Mean FCB concentrations at the sites were positively correlated with cumulative rainfall three to seven days and seven days prior to sampling. Presumed wildlife FCB levels were positively correlated to salinity and specific conductance, as well as cumulative rainfall. Regressions were used to make models for both FCB concentrations and presumed wildlife FCB concentrations in coastal stormwater ponds. 90% of the bacteria isolates found in both the ponds and creeks showed no antibiotic resistance and appeared to be of wildlife origin. Variables that explained the most variation within the model included different combinations of wind speed, rainfall, salinity, pH, temperature, and four different land classes. These variables explained between 33% and 49% of the variation in FCB concentrations. FCB models can be used to estimate FCB concentrations in coastal stormwater ponds and the influence wildlife have on these levels as well as serve as a tool to aid in water quality management and testing.

Simon, J.A., Snodgrass, J.W., Casey, R.E., and Sparling, D.W. 2009. Spatial correlates of amphibian use of constructed wetlands in an urban landscape. Landscape Ecology 24: 361-373.

Simon et al. (2009) investigated the relationship between land use, pollutant conditions, and amphibian use of wetlands in urban landscapes, using stormwater management ponds as their study sites. They used 18 stormwater ponds from the Baltimore-Washington metropolitan area that spanned a range of land uses including highway, residential, and commercial, and two reference wetlands. Species richness, land cover, and within-pond habitat was evaluated. They found 10 anuran species and one caudate species inhabiting the ponds. Land use was related to water chemistry and sediment metal levels, and metal levels were the best predictors of within-pond species richness. Stormwater ponds can play an important role in providing habitat for amphibian species and landscape characteristics (i.e., forest, impervious surface cover) within 5,000 to 1,000 meters of a pond was a strong predictor of which pond was likely to support a diverse community of amphibians.

Smith, E. M. 2012. Nutrient-Organic matter dynamics in stormwater ponds: Implications for stormwater management and the role of ponds as sources of coastal water quality impairment. [Extended Abstract]. South Carolina Water Resources Conference, Columbia, S.C.

Development and increases in impervious surface cover have altered the hydrological dynamics of stormwater runoff after rain events. Stormwater ponds are constructed to prevent flooding and manage runoff throughout the southeastern coastal plain. Using aerial imagery, over 14,000 ponds have been identified in S.C.’s coastal zone, representing a surface area of over 21,000 acres. Smith (2012) evaluated 26 residential ponds located throughout Georgetown and Horry counties, S.C. to examine the effects development has on pond ecosystems. Ponds ranged from low to high density, with two ponds located in a housing development that was never constructed. Smith (2012) found that TN ranged from 287.9 to 3758.5 mg N L-1 and TP ranged from 3.7 to 394.0 mg P L-1. Nutrient concentrations displayed both across and within pond variability but were found to be significantly different between medium/high residential density ponds and low density ponds. Nutrients also differed in their predominant forms. The majority of TN was in the dissolved form (71.9%), with DON accounting for almost all of the dissolved TN pool (DIN ~2.7%). Less than half of TP was in the dissolved form (36%), and the percent of the dissolved TP pool as DIP was larger and more variable (30.2%). Algal biomass varied among ponds and sampling dates. TN and TP both significantly predicated Chl a concentrations, however TP explained slightly more of the variability in chlorophyll than TN. TP driving algal biomass in this study is similar to that of natural lakes and is likely due to urbanized stormwater runoff containing greater levels of TP. Smith (2012) also found high total organic carbon concentrations with limited variability in DOC concentrations across ponds, however the labile portion of DOC was highly variable and significantly correlated with chlorophyll concentrations. This study also provided evidence that high algal biomass can convert nutrient inputs to dissolved organic forms which are then exported/discharged from ponds into downstream water bodies. Using a controlled mixing experiment, Smith (2012) found that while pond-derived DON had no impact on chlorophyll concentrations relative to controls compared to ammonium and nitrate, addition of pond-derived organic matter stimulated rates of heterotrophic bacterial production. Increased heterotrophic bacterial metabolism could worsen current low dissolved oxygen conditions throughout S.C. coastal waters.

Smith, E. 2013. Water quality in stormwater detention ponds and the impact of pond discharge on ecosystem processes within tidal creek receiving waters. [Abstract]. Tidal Creek Summit, Wilmington, NC.

In the northern portion of the S.C. coast, the number of stormwater ponds and cumulative surface area has increased 91% and 61% respectively from 1994-2006. Most of these ponds have direct discharge structures that drain into coastal waters, therefore it is important to understand water quality conditions in these ponds and the impacts of their discharge. Smith (2013) studied 26 residential ponds to address how they function as ecological systems, how they respond to nutrient enrichment, and the effects their discharges have on receiving waters. Bioassays revealed materials discharged from these ponds significantly increased the metabolic activity of heterotrophic microbial communities with the potential to alter the autotrophic/heterotrophic balance of tidal creeks.

Smith, E.M., Buck, T.L, Denham, S.A., and C.M. Cohen. Nutrient dynamics in stormwater detention ponds in coastal South Carolina, USA. 2015. [Poster]. Coastal and Estuarine Research Federation, Portland, OR.

Detention ponds have become the most popular BMP for controlling stormwater runoff and now represent the “headwaters” of many tidal creeks. Smith et al.’s (2015) objectives were to characterize nutrient conditions in stormwater ponds across a range of developmental densities, investigate nutrient availability, and assess how ponds retain and transform nutrient runoff. The ponds chosen for this study were in the Greater Myrtle Beach area. The objectives were evaluated using three different approaches. The first was in situ monitoring of nutrient and chlorophyll levels across a range of development (i.e. low, medium, and high residential development) in 26 ponds. A strong relationship was found between total phosphorous (TP) and chlorophyll, indicating the phytoplankton should be P limited. Second, nutrient addition bioassays were conducted in 12 ponds, and results found that primary productivity was mostly limited by N or co-limited by N and P. Lastly, two ponds were intensively studied to monitor total nitrogen (TN) and TP inflows and outflows. Smith et al. (2015) found that the ponds were effective at retaining these nutrients and that retention varied between nutrient form, with TP being more effectively retained than TN.

Sokol, E. R., Brown, B. L., Carey, C. C., Tornwall, B. M., Swan, C. M., and J.E. Barrett. 2015. Linking management to biodiversity in built ponds using metacommunity stimulation. Ecological Modelling 296: 36-45.

Sokol et al. (2015) investigated whether ponds managed for aesthetic and recreational purposes resulted in a homogenization of local habitats and biodiversity, focusing on zooplankton. They conducted surveys of zooplankton biodiversity between actively managed and unmanaged (based on whether algal management was occurring) built ponds in Columbia and Baltimore, Maryland. They also examined phytoplankton biomass, conductivity, DO, T, PO4, and NO3. Data used for analysis includes only the cladoceran and rotifer families, as other zooplankton groups (i.e., copepods) were not identified down to the same taxonomic level but are listed in the appendix. Results found that, except for conductivity, environmental variables did not significantly differ in managed and unmanaged ponds. Zooplankton communities did not differ between the two pond types but were related to environmental variation among the ponds. When the ponds were pooled together, salinity was the strongest link to zooplankton community composition. Overall, they found decreased beta-diversity of zooplankton in managed ponds, indicative of biotic homongenization. They also found Chl a levels were not different between pond types, despite one being treated with dye.

Sparling, D. W., Eisemann, J. D., and W. Kuenzel. 2004. Contaminant exposure and effects in red-winged blackbirds inhabiting stormwater retention ponds. Environmental Management 33(5): 719-729.

Sparling et al. (2004) investigated whether red-winged blackbirds that nested around 12 stormwater retention ponds in Maryland suburbs near Washington, DC were affected by contaminant exposure. The stormwater ponds were located in three different land-use categories: commercial, residential, and highway, and a reference wetland was selected in a national wildlife refuge. Results found that nesting success was comparable to national averages. However, it appeared that nestlings may have been stressed and impaired by elevated sediment zinc concentrations.

Strosnider, W. H., Hitchcock, D. R., Burke, M. K., and A.J. Lewitus. 2007. Predicting hydrology in wetlands designed for coastal stormwater management. ASABE publication #077084: 1-17pp.

Detention ponds are a frequently used BMP constructed to capture runoff along the S.C. coast. These ponds are designed to manage stormwater volume as opposed to improving water quality and frequently suffer from eutrophication due to high nitrogen loads. With the change in land use cover that is occurring with development, the natural cycling of N does not occur. The pond environment is not conducive for nitrification or denitrification, and therefore N accumulates in the form of NH4+. Stronsnider et al. (2007) modeled the hydrologic performance of a stormwater pond on Kiawah Island retrofitted with a constructed wetland in order to increase the denitrification rates to lower N loads in effluent. The hydrological performance of these wetlands was simulated with STELLA. One of the design options predicted a reduction of 74% and 92% of NH4+ and NO3 respectively and could significantly reduce nutrient loading to downstream ponds and estuaries.

Tufford, D. L., Samarghitan, C. L., McKellar Jr, H. N., Porter, D. E., and J.R. Hussey. 2003. Impacts of urbanization on nutrient concentrations in small southeastern coastal streams. Journal of the American Water Resources Association 39(2): 301-312.

Tufford et al. (2003) examined eight mixed land use basins that drain into Murrells Inlet and two undeveloped basins that drain into North Inlet estuary to study the effects of urbanization on water quality. Surface water grab samples were collected monthly from January to December of 1999. Tufford et al. (2003) found that the dissolved nitrogen fractions (DIN+DON) in urban ponds were ~62% while dissolved phosphorous fractions (DIP+DOP) were ~50%. The larger particulate fraction found in urban ponds compared to forested wetland creeks was likely attributed to the increased presence of phytoplankton. The calculated DIN:DIP ratio at the urban pond was 15.4 and the TN:TP ratio was 21.7.

Tufford, D. L., and W.D. Marshall. 2002. Fecal coliform source assessment in a small mixed land use watershed. Journal of the American Water Resources Association 38(6): 1625.

Sampling within the Rawls Creek watershed was conducted in the fall of 1999 and the winter of 2000. This watershed is characterized by numerous stream channels, storm drainage ditches, and ponds used for various purposes. Data collected from fall sampling found that water samples from the Subbasin 7 site, which occurs downstream from a large detention basin, was particularly high in fecal coliform levels. Nine hectares of this basin represents isolated forest tract, and therefore wildlife could be a major source of fecal coliform. It was also noted that at a site in Subbasin 4, sampling that occurred downstream from a rural pond surrounded by a cattle farm found only moderate FC levels, suggesting that this pond could be attenuating some of the bacterial loads. While ponds could be effective at reducing FC concentrations, they are also highly variable,and levels still remained above state water quality standards. Tufford and Marshall (2002) found that 46% of the variability within the data can be explained by impervious surface coverage.

Van Dolah, R.F., D.C. Bergquist, G.H.M. Riekerk, M.V. Levisen, S.E. Crowe, S.B. Wilde, D.E. Chestnut, W. McDermott, M.H. Fulton, E. Wirth, and J. Harvey. 2006. The condition of South Carolina habitats during 2003-2004: Technical report. Charleston, S.C.: South Carolina Marine Resources Division. Technical Report No. 101. 70 p.

This is the third technical report produced by South Carolina’s Estuarine and Coastal Assessment Program (SCECAP) that describes the status of South Carolina’s estuarine habitats. Sites are sampled for water quality parameters, sediment quality, and biological measures. Phytoplankton are analyzed as part of the biological conditions. Stormwater ponds can accumulate significant amounts of nonpoint source pollutants due to intensive lawn maintenance and turf management making them susceptible to blooms and HABs. Pond nutrient accumulation may impact estuarine eutrophication through surface or groundwater transport. Between 2000 to 2005, 325 blooms were recorded in brackish detention ponds and 25 in S.C.’s estuarine and coastal environment. Stormwater ponds can act as incubators for HAB species and as sources of HAB species into adjacent estuaries.

Vandiver, L., and D. Hernandez. 2009. Assessment of stormwater management in coastal South Carolina: A focus on stormwater ponds and low impact development (LID) practices.

Stormwater regulations in S.C. require the first half inch of runoff be retained on site or one inch of runoff from the built-upon area in order to maintain pre-development discharge rates. They also require that 80% of suspended solids be removed during the construction phase. Stormwater ponds are one type of BMP used to manage localized flooding and have recently been used as a means to treat stormwater and protect water quality in receiving water bodies. In 1999 there were estimated to be over 8,000 stormwater ponds in coastal S.C. They continue to be the most commonly used BMP due to their ease of design and construction, source of fill material, and ability to be marketed as an amenity. The efficacy of stormwater ponds as BMPs is dependent upon design characteristics such as length, width, placement of inlet and outlet pipes, storm characteristics, pond age, and pond size. Vandiver & Hernandez (2009) details information from a stormwater pond workshop where attendees stated that maintenance is a primary issue and listed other disadvantages of ponds to be water-volume impacts, the collection of pollutants, and variable efficacy. The attendees also indicated the need to supplement current stormwater ponds with additional BMPs to increase efficacy of stormwater retention and pollutant removal.

Wall, R. 2006. Ecological conditions of stormwater retention ponds. MS Thesis, University of Delaware, Wilmington, DE.

Wall (2006) investigated biotic and abiotic characteristics of stormwater ponds in New Castle County, DE and compared these characteristics to ponds constructed for other purposes (reference ponds). The stormwater ponds chosen were constructed by Delaware Department of Transportation and were adjacent to state highways. There are no natural ponds or lakes in DE, therefore the reference ponds were artificial as well but were not constructed for the purpose of stormwater retention and were not located next to a roadway. Sampling was conducted for two weeks in late April/early May of 2003. Wall used benthic organisms to assess biological resources. Water quality samples were taken to measure nutrient concentrations, and sediment samples were taken to determine contaminant levels. Results find no significant difference between stormwater ponds and reference ponds with respect to abiotic parameters. Biotic differences include higher number of individuals and percent Odonata organisms in the stormwater pond.

Weinstein, J.E., Crawford, K.D., and T.R. Garner. 2008. Chemical and biological contamination of stormwater detention pond sediments in coastal South Carolina: final project report. S.C. Sea Grant Consortium and SCDHEC-OCRM, Charleston, South Carolina.

Studies have found that contaminant levels of stormwater pond sediments can vary. Currently there are no requirements that stormwater pond sediments be tested for contaminants prior to sediment removal. Weinstein et al. (2008) characterized the chemical and biological contaminants in stormwater pond sediments in coastal South Carolina. Sixteen ponds were selected that were previously sampled in 2006 as part of a water quality survey conducted by SCDHEC-OCRM. Sediment samples were analyzed for grain size, TOC, PAH, metals, pesticides and other organics, fecal coliforms, and toxicity. TOC content widely varied, and fecal coliform levels ranged from low to moderately high but were independent of land use and sampling location. High levels were found at the inlet of one commercial pond and at the center of another pond (nine and 11 times higher than other commercial ponds).

Williamson, K. E., Harries, J. V., Green, J. C., Rahman, F, and R. M. Chambers. 2014. Stormwater runoff drives viral community composition changes in inland freshwaters. Frontiers in Microbiology 5: 1-14.

Williamson et al. (2014) examined how freshwater viral communities responded to disturbances by storms and the subsequent influx of stormwater runoff. They hypothesized that changes in viral community composition are caused by the influx of novel virus taxa in stormwater runoff. Field sampling was conducted in a stormwater retention pond in Williamsburg, VA over the course of two major storms. They analyzed viral abundance and changes in viral community composition as well as environmental parameters (T, conductivity, DO, nutrients). Results found that time was the most important variable explaining viral community composition. Particle-associated viruses made up a high percentage of the total viral abundance, which was best explained by conductivity and bacterial abundance during both storm events. There hypothesis was supported by MRT analysis which revealed discontinuities in community structure coinciding with peak precipitation.

Winston, R. J., Hunt, W. F., Kennedy, S. G., Merriman, L. S., Chandler, J., and D. Brown. 2013. Evaluation of floating treatment wetlands as retrofits to existing stormwater retention ponds. Ecological Engineering 54: 254-265.

Wet retention basins are a widely used stormwater control measure, however a lack of literature exists on the performance of wet ponds for pollutant removal. The objective of this study was to assess the impact of adding floating treatment wetlands (FTWs) to stormwater ponds on pollutant removal, temperature, and effluent quality. Two wet ponds in Durham, N.C. were monitored pre and post retrofit. The DOT pond was inhabited by invasive creeping water primrose and frequented by Canada geese. The Museum Pond had a forebay vegetated with a dense matt of cattails. Pre-retrofit monitoring took place for 14 months between December 2008 and February 2010, and 16 paired samples were collected from the inlet and outlet of each pond. Winston et al. (2013) found that the DOT pond performed well for TN, TP, and TSS reduction, significantly reducing NO2-3-N, PBP, and TSS. Reductions were also made in TN, TP, and TSS at the Museum pond, with significant reductions in TKN, TAN, ON, PBP, and TSS. Post-retrofit they found the DOT pond was able to reduce seven of the nine analytes studied, and the Museum pond reduced all nine analytes.

Wisniewski, N. L. (2014). The influence of nitrogen forms on the growth and toxin levels of microcystin-producing cyanobacteria in coastal stormwater detention ponds. MS thesis, College of Charleston, Charleston, S.C.

The goal of this study was to assess the influence of N form on phytoplankton growth, assemblage composition, and microcystin levels in two stormwater detention ponds (K05 & K109) on Kiawah Island. The study was conducted from June 2013-May 2014, with sampling conducted twice per month from June to October and once per month from November to April. Nutrient addition bioassays were also deployed at the two ponds in June and August. Most of the TN pool at both ponds consisted of DON, which has been shown to be a preferable N source for cyanobacteria species. There were high initial P concentrations at both sites, indicating the ponds were not P limited. Wisniewski (2014) found that chl a levels significantly varied between sites and treatments but were not significant between months. N additions, particularly urea, stimulated phytoplankton growth. Chlorophytes, dinoflagellates, centric diatoms, and both diazotrophic and non-diazotrophic cyanobacterial species were most abundant. Evaluation of microcystin concentrations found non-detectable and minimal levels.