Keiser and Associates evaluated the water quality of Asylum Lake and Little Asylum Lake from 2006 to 2008. The purpose of the assessment was to develop a better understanding of current lake conditions, identify factors influencing water quality and recommend strategies for long-term management and improvement.
Efforts of the study included:
- Watershed delineation and assessment of runoff contributions.
- Identification of stormwater pollutant sources and loading estimates.
- Water quality monitoring (seasonal and wet weather).
- Stormwater inlet and lake outlet sampling.
- Sediment sampling.
- Aquatic plant surveying.
- Development of a hydraulic mass balance.
- Development of a phosphorous mass balance.
- Best management practice recommendations and preliminary stormwater treatment concepts.
The study found both lakes to be considered mesotrophic to eutrophic, meaning they are experiencing an overload of nutrients. Stormwater inputs are significant, and pollutants are mainly entering the lake from drains located near Drake Road and Stadium Drive. Large concentrations of phosphorous were found at the bottom of the lake and in the sediments. Heavy metals such as mercury were also found in bottom waters and in sediments, most likely from atmospheric and stormwater sources. Anoxic conditions were recorded indicating high sediment oxygen demand. Recommendations for improving the health of the lakes included invasive species management, stormwater control and sediment or hypolimnetic treatments.
A detailed description of the methods and results of the study can be found in the PDFs listed below.