Stormwater Detention Ponds Research Articles

Assessment of a countywide stormwater pond improvement program

Numerous approaches have been advocated to improve pollutant removal in stormwater retention and detention ponds. The Hillsborough County (FL) Adopt-A-Pond program is one such application. However, ex post evaluation of these approaches is particularly limited. Water quality and vegetative characteristics were assessed at participating Adopt-A-Pond sites to explore potential impacts of the program on measurable environmental parameters. Statistical analysis of the results failed to demonstrate significant environmental improvements associated with the Adopt-A-Pond program, and measures of program activity did not illustrate a consistently positive influence. These results illustrate the need for ex post evaluations and indicate a general need to readdress the policies and implementation of the program. Poor compliance by program volunteers, evident by the limited span of group participation (mean = 2.5 years) and relatively low percentage of actively involved residents, is a possible culprit, as the efficacy of pond enhancement techniques is firmly established in the literature.

Performances of Two Macrophytes Species in Floating Treatment Wetlands for Cadmium, Nickel, and Zinc Removal from Urban Stormwater Runoff

Conventional stormwater detention ponds frequently show limitations for dissolved heavy metal removal. Floating treatment wetlands (FTWs), a variant of constructed wetlands, are considered as a promising technology to improve the quality of urban stormwater runoff. Our study aimed at evaluating the treatment performances of FTWs for cadmium, nickel, and zinc removal through a pot experiment. Two macrophytes species, Juncus effusus and Carex riparia, were grown during 4 months under three metal concentrations (in micrograms per liter): high (Cd, 200; Ni, 500; Zn, 2,000), low (Cd, 10; Ni, 10; Zn, 40), and control (Cd–Ni–Zn, 0). Results showed that both macrophytes species significantly removed dissolved heavy metals. Cadmium and nickel accumulations were greater in roots than in shoots for both species. Under low metal concentration, maximum accumulation of 0.4 μg g−1 dry weight (DW) for Cd was observed in the roots of J. effusus. Under high metal concentration, accumulations of up to 5 μg Cd g−1 DW and 62 μg Ni g−1 DW were observed in the roots of J. effusus and up to 73 μg Zn g−1 DW in the roots of C. riparia. Although J. effusus and C. riparia are not recognized as metal hyperaccumulators, our study demonstrated that they can achieve high metal uptake when both roots and shoots are harvested.

Detention Pond Sediment Accumulation Prediction using Monte Carlo Simulation

Problem statement: A study in Malaysia had been carried out to predic t the sediment accumulation in urban detention ponds. Suspended sediment is pollutant of primary concern to the river that results in adverse environmental effect. Detention pond becomes a practical approach to thi s problem. Suspended sediment that settled in stormwater detention pond, can bring effect to the detention pond functions. Questions were raised on how certain were the observed and predicted values of sediment depth and load accumulation esti mations. Secondly the question was what the sediment accumulation be in the next 100 years. The uncertainties of sediments estimation vary greatly due to the hydrological variability and rainfall ra ndom nature obtain the relationship between flow discharge and suspended sediment rate using on-site data collection at UTM and Ledang Heights, Nusajaya. Predict accumulated sediment loads and depth from MUSLE over 10-100 years. Analyze the uncertainties of sediment loads and depth using Monte Carlo Simulation (MCS) combining normal distribution. Obtain the maximum probability of occ urrence of sediment loads and depth in the detention pond. Approach: Modified Universal Soil Loss Equation (MUSLE) and Trap Efficiency (TE) Method was applied to predict sediment accumulation. This uncertainty of sediment loads and depth was carried out using Monte Carlo Simulation (MCS) Method. The water samples were collected for suspended solids data and other water quality parameters at Ledang Heights, Nusajaya, Johor and University Technology Malaysia (UTM), Johor. Sampling station were randomly selected at the inlet and outlet of the detention pond. The hydrological parameters such as flow and velocity were also collected. Results: The simulation results showed the maximum probability of occurrence value for observed sediment loads and sediment dept h from Ledang Heights were 0.0062 tons (16.5%) and 0.0005 mm (17.5%) respectively. The maximum probability of occurrence values for observed sediment loads and sediment depth at UTM showed no obvious differences with Ledang Heights; about 0.015 tons (16.8%) and 0.00037 mm (15.5%) respectively. The maximum occurrence of predicted sediment loads and sediment depth usin g MUSLE method for Ledang Height was 77.8 tons (16.8%) and 7.5 mm (26.8%) respectively. The maximum occurrence for UTM was slightly higher, about 264 tons (15.70%) and 7.0 mm (21.10%) respectively. The higher values for UTM were suspected due to its larger watershed. The sediment loads and depths were also predicted for the next 50-100 years considering no significant watershed l and use changes. Conclusion: The sediment accumulation estimation and forecasting are very important to ensure the effectiveness and proper operation of the detention pond. The continuous eff ort through natural sediment control measures such as proper vegetation and grass inplants are always encourage around the detention pond and surrounding areas throughout its lifespan.

Assessing biological and chemical signatures related to nutrient removal by floating islands in stormwater mesocosms

Aquatic floating plants on BioHaven mats were tested for their potential use as a Best Management Practice to be incorporated within existing stormwater detention ponds. Plants were analyzed for their capability to remove nutrient-pollution in parallel with the study of ecological dynamics. Experiments were carried out in cylindrical mesocosms of 5m diameter and 1.2m height, above-ground pools with a water volume of 14m3. The design parameters tested were for 5% and 10% vegetated floating island coverage of the mesocosm, both with and without shoreline plants called littoral zone. This littoral shelf was 0.5m thick, graded at a downward slope of 1:5 toward the center using loamy soil with low organic matter content, excavated from below turf grass. Endemic plant species were chosen for the experimental location in central Florida based on a wetland identification manual by the Florida Department of Environmental Protection to ensure the study was not compromised by unique climate requirements of the plants. Nutrient and aquatic chemical conditions such as pH, dissolved oxygen, temperature, turbidity, and chlorophyll a were monitored to understand their relationships to the general wetland ecosystem. Real-time polymerase chain reaction analysis identified the microbial activity near the rhizospheric zone. Logistical placement considerations were made using spatial sampling across the horizontal plane of the mesocosms, beneath and around the root zone, to determine if nutrients tend to aggregate around the floating island. This study concluded that the application of floating islands as a stormwater technology can remove nutrients through plant uptake and biological activity. The most cost-effective size in the outdoor mesocosms was 5% surface area coverage of the mat.

Optimal design of stormwater detention basin using the genetic algorithm

The urbanization of an undeveloped area often shortens outflow travel time and increases peak discharge from the basin, thereby increasing the downstream flood frequency. Stormwater detention ponds are the most common measure to maintain the outflow from the post-developed basin to a flow similar to that under the pre-developed condition. The design criteria of stormwater detention ponds are to minimize construction cost while achieving the flood control purpose. The tedious and time-consuming, trial-and-error method is commonly used to determine the optimal size and location of the pond and outlet structure for a design storm period. In this study, a stochastic search algorithm, a Genetic Algorithm (GA), is used to optimize the detention pond design. The decision variables are the pond storage, and the pipe diameters and number of pipes for the service outlet. The flood control objective considered in this study is that the peak discharge in the post-developed condition does not exceed that under the pre-developed condition and that the maximum water level in the pond during the flood remains below the allowable water level. The proposed optimization algorithm method was applied to the real design of two detention ponds in South Korea, where it generated better design options comprising smaller pond storage and smaller outlet standpipe dimensions than those of the traditional trial-and-error method, and in a much shorter computational time. Therefore, the stochastic search algorithm, GA, can be successfully applied in the design of a stormwater detention basin to improve accuracy and convenience. The engineers can accordingly assess the development plan in terms of the potential basin disaster more efficiently than is possible when using the tedious computation method.

Hydroclimatology of flash flooding in Atlanta

The objective of this study is to characterize the climatology of extreme rainfall and flash flooding in Atlanta, Georgia using high‐resolution land surface, rainfall, and discharge datasets. We examine nine urban watersheds in the Atlanta area that range in size from 3.7 to 225 km2 and exhibit a range of urban development and land‐use characteristics. We develop a high‐resolution 15 min, 1 km2 radar rainfall data set for the 2002–2010 period using the Hydro‐NEXRAD system with volume scan reflectivity observations from the Atlanta WSR‐88D radar and rainfall observations from a dense network of 72 U.S. Geological Survey rain gauges. Bias‐corrected radar rainfall fields accurately capture the spatial and temporal structure of heavy rainfall. There is enhancement of heavy rainfall within and east of the urban core, and a rainfall minimum north and northwest of the city. There has been an increase in variability of annual flood peaks in Atlanta since the 1960s associated with urban impacts on runoff production. Flood response is dependent on a combination of basin size, drainage network structure, spatial distribution of land use, and basin storage in urban soils and storm water detention ponds. Future studies of urban rainfall modification in Atlanta and elsewhere should consider the influence of regional topography and other geographic features on the storm environment.

Ameliorative effects of sodium chloride on acute copper toxicity among Cope's gray tree frog (Hyla chrysoscelis) and green frog (Rana clamitans) embryos

Urban stormwater runoff is composed of a mixture of components, including polycyclic aromatic hydrocarbons, metals, deicing agents, and many others. The fate of these chemicals is often in stormwater detention ponds that are used by amphibians for breeding. Among aquatic organisms, the toxic mechanism for many metals involves interference with active Na(+) and Cl(-) uptake. Addition of cations has been shown to reduce the toxicity of metals among some aquatic organisms through competitive inhibition, but no studies have investigated the interaction between NaCl and Cu among amphibian embryos and larvae. To determine the degree to which NaCl may ameliorate the toxicity of Cu to amphibian embryos and larvae, the authors exposed Hyla chrysoscelis (Cope's gray treefrogs) and Rana (Lithobates) clamitans (green frogs) to seven levels of Cu and NaCl in fully factorial experiments. When exposure was in artificial hard water, Cu was highly toxic to both species (96-h median lethal concentration [LC50] of 44.7 µg/L and 162.6 µg/L for H. chrysoscelis and R. clamitans, respectively). However, approximately 500 mg/L of NaCl eliminated Cu toxicity over the range of Cu concentrations used in the experiments (maximum 150 µg Cu/L for H. chrysoscelis and 325 µg Cu/L for R. clamitans). The current results suggest that NaCl is likely responsible for the toxic effects of NaCl and metal mixtures that might be typical of runoff from road surfaces in northern latitudes.

Use of a Storm water Retention System for Conservation of Regionally Endangered Fishes

ABSTRACTMaintaining aquatic biodiversity in urban or suburban areas can be problematic because urban landscapes can be nearly devoid of aquatic habitats other than engineered basins for storm water management. These areas are usually of questionable value for fish, but we examined a case study in which five regionally imperiled fish species were reintroduced into an artificial storm water detention pond and subsequently thrived. Although not a formal experiment, postintroduction survey data suggested that three of the five species maintained high population densities for 10 years after initial stocking, and two persisted in lower numbers. Success was likely due to a combination of unique design features and prior habitat preparation that resulted in clear water conditions that supported dense vegetation. Stocked fish persisted despite occasional bouts of low dissolved oxygen and increased chloride levels resulting from road salt application within the watershed. Transplanted fish served as a source population for both research and further reintroduction experiments. We suggest that, for some fish species, habitat preservation has a middle ground between natural habitats and completely artificial environments that require constant husbandry and that storm water systems could be used to create engineered sanctuaries within the human landscape that have many potential benefits for both humans and fish.

Nutrient controls of planktonic cyanobacteria biomass in coastal stormwater detention ponds

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 434:15-27 (2011) - DOI: https://doi.org/10.3354/meps09195 Nutrient controls of planktonic cyanobacteria biomass in coastal stormwater detention ponds Amy Siegel1, Bridget Cotti-Rausch1, Dianne I. Greenfield1,2,4, James L. Pinckney1,3,* 1Marine Science Program, 2Belle W. Baruch Institute for Marine and Coastal Sciences, and 3Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA 4Marine Resources Research Institute, 217 Fort Johnson Road, Charleston, South Carolina 29412, USA *Corresponding author. Email: pinckney@sc.edu ABSTRACT: Stormwater detention ponds are a common best management practice (BMP) designed to moderate the impacts of development on surrounding ecosystems. On Kiawah Island, South Carolina, stormwater detention ponds receive high levels of nitrogen (N) and phosphorus (P) loading from non-point sources, which results in eutrophic conditions, recurrent water quality degradation, and problematic cyanobacterial blooms during summer and fall. The purpose of this study was to quantify planktonic cyanobacterial responses to manipulations of the form of N (NO3–, NH4+, urea, or combinations) to determine their relative importance for cyanobacterial blooms. Nutrient addition bioassays were performed monthly (June to September 2009) in 2 brackish water ponds designated as K61 and K67. The 2 study sites were similar in all physical parameters except pond K61 was more brackish (salinity = 14 ± 2, mean ± SD) than pond K67 (6 ± 2). Urea additions resulted in a greater increase in cyanobacterial biomass than other N forms in pond K61 while urea and NH4+ additions promoted growth in pond K67. The bioassays showed a relatively strong cyanobacteria response to the N additions for both ponds (except K67 in July). However, in all cases, the cyanobacterial contribution was always <36% of total phytoplankton biomass. Our results suggest that both NH4+ and urea may preferentially stimulate cyanobacterial growth in brackish stormwater detention ponds on Kiawah Island in the summer months. Although fertilizer application procedures and rates are not known for the areas drained by the stormwater detention ponds on Kiawah Island, our results suggest that the use of urea-based fertilizers, which produce both urea and NH4+ in runoff, could foster the development and maintenance of cyanobacteria blooms. KEY WORDS: Photopigment · Bioassay · Nutrient · Eutrophication · HPLC · Urea · Ammonium · Nitrate · ChemTax Full text in pdf format PreviousNextCite this article as: Siegel A, Cotti-Rausch B, Greenfield DI, Pinckney JL (2011) Nutrient controls of planktonic cyanobacteria biomass in coastal stormwater detention ponds. Mar Ecol Prog Ser 434:15-27. https://doi.org/10.3354/meps09195 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 434. Online publication date: July 28, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Monitoring Nitrogen Loading and Retention in an Urban Stormwater Detention Pond

Stormwater detention ponds have become ubiquitous in urbanized areas and have been suggested as potential hotspots of N transformation within urban watersheds. As a result, there is a great deal of interest in their use as structural best management practices to reduce the excessive N export from these watersheds. We conducted continuous monitoring of the influent and effluent N loads of a stormwater detention pond located on the Princeton University campus in Princeton, New Jersey. Our monitoring was conducted during four 21-d periods representing the four seasons of the northeastern United States. Water quality samples were collected and analyzed for nitrate (NO3-) during all four monitoring periods. During two of these periods, loads of ammonium (NH4+), dissolved organic N, and particulate N (PN) were measured. Our results show that NO3- dominated the influent N load, particularly in dry weather inflows to the detention pond. However, PN, which is often neglected in stormwater quality monitoring, made up as much as 30% of the total load and an even greater fraction during storm events. The results of our monitoring suggest that seasonal variation may play an important role in N retention within the detention pond. Although retention of NO3-, the most dominant fraction of N in the influent stormwater, was observed during the summer sampling period, no significant NO3- retention was observed during the spring or the two cold-weather sampling periods.

A novel tracer technique for the assessment of fine sediment dynamics in urban water management systems

Urban storm water run off can reduce the quality of receiving waters due to high sediment load and associated sediment-bound contaminants. Consequently, urban water management systems, such as detention ponds, that both modify water quantity through storage and improve water quality through sediment retention are frequently-used best management practices. To manage such systems effectively and to improve their efficiency, there is a need to understand the dynamics (transport and settling) of sediment, and in particular the fine sediment fraction (<63 μm) and its associated contaminants within urban storm water management systems. This can be difficult to achieve, as modelling the transport behaviour of fine-grained and cohesive sediment is problematic and field-based measurements can be costly, time-consuming and unrepresentative. The aim of this study was to test the application of a novel cohesive sediment tracer and to determine fine sediment transport dynamics within a storm water detention pond. The cohesive sediment tracer used was a holmium labelled montmorillonite clay which flocculated and had similar size and settling velocity to the natural pond sediment it was intended to mimic. The tracer demonstrated that fine sediment was deposited across the entire pond, with the presence of reed beds and water depth being important factors for maximising sediment retention. The results of the sediment tracer experiment were in good agreement with those of a mathematical sediment transport model. Here, the deposited sediment tracer was sampled by collecting and analysing surface pond sediments for holmium. However, analysis and sampling of the three dimensional suspended tracer ‘cloud’ may provide more accurate information regarding internal pond sediment dynamics.

Measurement of Vertical Temperature Profiles in a Stormwater Detention Pond

During and subsequent to a rainfall event, stormwater runoff can transport heat from an urban area (which can be significantly warmer than its surrounding regi…

Comparison of CFD with Reservoir Routing Model Predictions for Stormwater Ponds

The hydraulic design of stormwater detention ponds is usually directed towards outflow peak reduction. It is generally calculated with the reservoir routing ap…

Screening-level ecological and human health risk assessment of polycyclic aromatic hydrocarbons in stormwater detention pond sediments of Coastal South Carolina, USA

Screening-level ecological and human health assessments were performed for polycyclic aromatic hydrocarbon (PAH) contamination in the sediments of 19 stormwater detention ponds located in coastal South Carolina. For ecological screening benchmarks, we used threshold and probable effect concentrations (TEC and PEC) derived from consensus-based sediment quality guidelines for individual PAH analytes and equilibrium partitioning sediment benchmarks-toxic units (SigmaESB-TU) derived for PAH mixtures. For human health benchmarks, we used preliminary remediation goals (PRGs). Sediments of five stormwater ponds (four commercial ponds and one residential pond with a large drainage area) exceeded PEC values for several PAH analytes and the SigmaESB-TU safe value of 1 for PAH mixtures. These same five stormwater ponds also exceeded the PRG values for five carcinogenic PAH analytes. These results suggest that the PAH levels in sediments from certain commercial and residential ponds have the potential to pose moderate to high risks for adverse, chronic effects to benthic organisms in situ and an increased risk of cancer to humans ex situ following excavation and on-site disposal. We recommend that sediment from these stormwater ponds be tested prior to excavation to determine the appropriate method of disposal. We also recommend that regulatory agencies enforce guidelines for periodic sediment removal as this should reduce both in situ and ex situ risks resulting from sediment PAH exposure.

Simulation of Temperature Mitigation by a Stormwater Detention Pond1

Abstract: A numerical model has been developed to simulate the hydraulic and heat transfer properties of a stormwater detention pond, as part of a simulation tool to evaluate thermal pollution of coldwater streams from stormwater runoff. The model is dynamic (unsteady) and based on principles of fluid mechanics and heat transfer. It is driven by hourly weather data, and specified inflow rates and temperatures. To calibrate and validate the pond model field data were collected on a commercial site in Woodbury, Minnesota. The relationship between pond inflow and outflow rates to precipitation was effectively calibrated using continuously recorded pond levels. Algorithms developed for surface heat transfer in lakes were found to be applicable to the pond with some modification, resulting in agreement of simulated and observed pond surface temperature within 1.0°C root mean square error. The use of an unshaded pond for thermal mitigation of runoff from paved surfaces was evaluated using the pond model combined with simulated runoff from an asphalt parking lot for six years of observed rainfall events. On average, pond outflow temperature was 1.2°C higher than inflow temperature, but with significant event‐to‐event variation. On average, the pond added heat energy to runoff from an asphalt parking lot. Although the pond added total heat energy to runoff, it did reduce the rate of heat outflow from the pond by an order of magnitude due to reductions in volumetric outflow rate compared with the inflow rate. By reducing the rate of heat flow, the magnitude of temperature impacts in a receiving stream were also reduced, but the duration of impacts was increased.

A Survey of Metal and Pesticide Levels in Stormwater Retention Pond Sediments in Coastal South Carolina

During the summer of 2007, sediment samples were collected from 16 stormwater detention ponds and 2 reference ponds located in coastal South Carolina. The sediments were analyzed for more than 30 pesticides with current and historical uses, six polybrominated diphenyl ethers (PBDEs), and seven metals. The results are compared with established screening assessment parameters, with copper found to be the contaminant of highest concern. Lead levels were found to correlate well with pond drainage area, while copper and zinc levels correlated with both pond drainage area and pond surface area. Chlorpyrifos levels were found to correlate with pond surface area. Our results also show that ponds draining commercial areas were likely to have higher levels of zinc and lead in the sediments compared to other pond classes.

Polycyclic aromatic hydrocarbon contamination in stormwater detention pond sediments in coastal South Carolina

The purpose of this study was to characterize the polycyclic aromatic hydrocarbon (PAH) contamination in the sediments of stormwater detention ponds in coastal South Carolina. Levels of the sum of PAH analytes were significantly higher in the sediments of commercial ponds compared to that of reference, golf course, low-density residential, and high-density residential ponds. Isomer ratio analysis suggested that the predominant source of PAHs were pyrogenic; however, many ponds had a PAH signature consistent with mixed uncombusted and combusted PAH sources. PAH levels in these sediments could be modeled using both pond drainage area and pond surface area. These results demonstrate that the sediment from most commercial ponds, and a few residential and golf course ponds, were moderately contaminated with PAHs. PAH levels in these contaminated ponds exceeded between 42% and 75% of the ecological screening values for individual PAH analytes established by US EPA Region IV, suggesting that they may pose a toxicological risk to wildlife.

Phytoremediation to remove nutrients and improve eutrophic stormwaters using water lettuce (Pistia stratiotes L.)

Water quality impairment by nutrient enrichment from agricultural activities has been a concern worldwide. Phytoremediation technology using aquatic plants in constructed wetlands and stormwater detention ponds is increasingly applied to remediate eutrophic waters. The objectives of this study were to evaluate the effectiveness and potential of water lettuce (Pistia stratiotes L.) in removing nutrients including nitrogen (N) and phosphorus (P) from stormwater in the constructed water detention systems before it is discharged into the St. Lucie Estuary, an important surface water system in Florida, using phytoremediation technologies. In this study, water lettuce (P. stratiotes) was planted in the treatment plots of two stormwater detention ponds (East and West Ponds) in 2005-2007 and water samples from both treatment and control plots were weekly collected and analyzed for water quality properties including pH, electrical conductivity, turbidity, suspended solids, and nutrients (N and P). Optimum plant density was maintained and plant samples were collected monthly and analyzed for nutrient contents. Water quality in both ponds was improved, as evidenced by decreases in water turbidity, suspended solids, and nutrient concentrations. Water turbidity was decreased by more than 60%. Inorganic N (NH(4) (+) and NO(3) (-)) concentrations in treatment plots were more than 50% lower than those in control plots (without plant). Reductions in both PO(4) (3-) and total P were approximately 14-31%, as compared to the control plots. Water lettuce contained average N and P concentrations of 17 and 3.0 g kg(-1), respectively, and removed 190-329 kg N ha(-1) and 25-34 kg P ha(-1) annually. Many aquatic plants have been used to remove nutrients from eutrophic waters but water lettuce proved superior to most other plants in nutrient removal efficiency, owing to its rapid growth and high biomass yield potential. However, the growth and nutrient removal potential are affected by many factors such as temperature, water salinity, and physiological limitations of the plant. Low temperature, high concentration of salts, and low concentration of nutrients may reduce the performance of this plant in removing nutrients. The results from this study indicate that water lettuce has a great potential in removing N and P from eutrophic stormwaters and improving other water quality properties.

Lagoonal stormwater detention ponds as promoters of harmful algal blooms and eutrophication along the South Carolina coast

In the rapidly urbanizing coastal zone of South Carolina, intensive landscape maintenance and turf management are significant sources of nonpoint source pollutant loadings. The best management practice of choice for stormwater in this region is wet detention ponds, the majority of which are brackish lagoons. Typically, stormwater is piped directly into the ponds, but ponds have limited capacity for processing pollutants. These eutrophic brackish ponds are “hot spots” for harmful algal blooms (HABs)—over 200 blooms from 23 different species were documented over the last 4 years, many associated with measured toxins, fish kills or shellfish health problems. Because these ponds exchange with tidal creeks, they are potential sources for HAB dispersion into adjacent estuaries. Also, flux measurements indicated that groundwater was both a source of nutrients to the ponds and a mechanism for transporting nutrients from the ponds. These findings suggest that manmade ponds as presently designed along the SC coast may contribute to estuarine eutrophication and HAB prevalence. A summary of HAB occurrences in SC lagoonal ponds from 2001 to 2005 is presented, and a project is described that simulates the effectiveness of constructed wetlands as a supplementary best management practice designed to process stormwater and groundwater and remove nutrients prior to entering wet detention ponds.

Geochemistry and toxicity of sediment porewater in a salt-impacted urban stormwater detention pond

A comprehensive study was carried out to investigate the impacts of road salts on the benthic compartment of a small urban detention facility, Rouge River Pond. Although the pond is an engineered water body, it is representative of many small urban lakes, ponds and wetlands, which receive road runoff and are probable high impact areas. Specific objectives of the study were to document the porewater chemistry of an aquatic system affected by elevated salt concentrations and to carry out a toxicological assessment of sediment porewater to determine what factors may cause porewater toxicity. The results indicate that the sediment porewater may itself attain high salt concentrations. The computations show that increased chloride levels have important implications on the Cd complexation, augmenting its concentration in porewater. The toxicity tests suggest that the toxicity in porewater is caused by metals or other toxic chemicals, rather than high levels of chloride.