CofC Logo

Research

Research
  1. To detect water quality problems in residential retention ponds and factors responsible for water quality degradation.
  2. Identify which homeowner's practices will have some impact on the retention pond water quality.
  3. Increase of community (homeowners and students) interest towards the water quality problems in retention ponds through their education and involvement in the management techniques of water quality restoration project.

This page will outline various areas of the research. These include:


Sample Site - Lake Edmonds

  • Lake Edmonds was used as a model retention pond
  • Private property of Lake Edmonds Homeowner Association
  • 11 acre fresh water lake with a drainage area = 107 acres (~ 300 houses)
  • After rain events, Lake Edmonds overflows into Kushiwah Creek leading to land contaminant transfer into estuary and Charleston Harbor. (See map)
  • Wildlife habitat
  • Aesthetic value
  • Recreational uses (boating, fishing)

Methodology

To determine water quality problems in Lake Edmonds, different parameters were measured. These parameters included:


Results

  • >25% of the samples exceeded the recreational uses guideline for fecal coliform bacteria of 200CFU/100mL (i.e. July, August, November and December 2004, and May 2005) (Graph 1)
  • Nitrogen levels exceeded eutrophic guidelines (>0.37mg/L) in June, November and December 2004 and February, March and June 2005 (Graph 2)
  • Phosphorus levels exceeded eutrophic guidelines (>0.036mg/L) in all samples throughout the sampling period 2004-2005 (Graph 3)
  • All samples for Lake Edmonds had higher chlorophyll levels than the eutrophic standard of 4.1ug/L (Graph 4)
  • Algal blooms (>1,000cells/mL) were developed by species of the cyanobacterial genera Anabaena (Graph 5) and Microcystis (Graph 6) in summer months and November and December 2004 (associated with high migratory bird density at Lake Edmonds).
  • Few detections of microcystin, equal or greater than the human protection standard of 1ug/L microcystin-LR (Table 1).
  • Persistent herbicide (Atrazine and 2,4-D) concentration throughout summer and spring seasons (Graph 7).

Residents Survey and Results

Residences in Lake Edmonds' drainage area were grouped as:

  • Residents within the Lake Edmonds Homeowners Association - Download Results (xls, 27 KB)
  • Residents included in the lake's watershed - Download Results (xls, 40 KB)
The survey assessed:
  • pet waste management
  • fertilizer and pesticide application
  • homeowners' interest in the retention pond water quality problems
  • willingness to change practices in order to improve water quality

Human practices showed to have a significant influence on pond water quality included:

  • high density and frequency of lawn care product application
  • poor pet waste management
  • absence of a vegetative buffer along the pond's edge

To see a detailed overview of the findings, visit the survey results.


Conclusions

After the analysis of data collected and the information obtained from the survey, we concluded that water quality problems do exist in Lake Edmonds due to the following aspects:

  • High nutrient (nitrogen and phosphorus) concentration, explained by high density (>76% of residents) and frequency (>2 times per year) of fertilizer applied by residents living at Lake Edmonds' watershed
  • Algal bloom development due to fecal matter input, fertilizer and household waste water runoff
  • Persistent herbicide concentration due to runoff of chemicals such as herbicides (atrazine and 2,4-D) after application to lawns, especially after rain event
  • Algal toxin production due to algal bloom formation
  • High fecal coliform bacteria concentration due to fecal matter deposition of pets and wildlife
  • The results of the resident's survey indicated some of the human practices that have an effect in water quality at Lake Edmonds. These include the following:
    • Frequent fertilizer and pesticide application
    • Runoff of household products
    • Poor pet waste management
    • Lawn clipping deposition on the water
    • Deforestation (absence of vegetative buffer at lake's edge)
  • Results of this study indicated that a long-term monitoring would be necessary to determine effectiveness of management strategies.
  • Although individual homeowners changes in practices can make a difference a watershed approach management would be more effective in water quality improvement
  • Stormwater ponds with poor maintenance can act as contamination sources to adjacent estuaries, and may possess a risks to human, pet and wildlife health