Executive Summary
This preliminary 2022 study provides an assessment of recreational impacts on sensitive environmental values and sediment quality (or sediment suspension) at Windermere Lake. The purpose of this report is to provide guidance for implementation of the full work program in 2023.
Sediment cores and existing habitat related data were used to help determine potential risks to environmental values and those associated with sediment disruption or contamination resulting from ongoing and active recreational use. Sediment cores showed detectable hydrocarbons at 6 of 9 sites distributed through the lake. The highest recorded hydrocarbon result was 460 mg/kg of EPH 19-32 (extractable petroleum hydrocarbons), measured at the Rockier Sediment site. The field crew noted a hydrocarbon odor when they took sediment cores in marinas, supporting detection of EPH 19-32. Sediment quality guidelines are not set for EPHs because it is a broad category of hydrocarbons. More detailed VOC (volatile organic compounds), BTEX (benzene, toluene, ethylbenzene and xylene), or PAH (Polycyclic aromatic hydrocarbons) analyses panels would be needed for guideline comparison. The results from the first sampling trip indicate there would be value in a more thorough investigation of hydrocarbon contamination in Windermere Lake at a larger scale.
Phytoplankton densities were moderate in the southern half of the lake while the northern two sites had very high densities and were dominated by the bloom forming1 and potentially toxic cyanobacteria Anacystis sp. The beach sample contained 21,410 cells/mL of cyanobacteria, a concerning result for a popular swimming area. While this is unlikely to lead to acute cyanotoxicity, chronic low dose exposure cannot be ruled out.
A method assessing boat density on the lake was also created by the team for the first year. Data was collected and revisions and recommendations to a full year of data collection have been provided. The intent of this study is to determine areas with the greatest recreational use. Following that, recommendations for the most appropriate recreational areas will be provided, considering environmental values for the lake and overall sediment quality.
Read the full memo here