| Abstract/Description or Keywords |
This report assesses the water quality of Williams Lake and sets provisional water quality objectives to protect its use for drinking water, recreation and aquatic life. The main inflow into Williams Lake is the San Jose River which drains the area to the south including Lac la Hache. Williams Lake then drains into the Fraser River about 120 km south of Quesnel. The lake water is used for domestic, irrigation and industrial purposes. The City of Williams Lake used the lake as a source of drinking water but now obtains most of its water from wells adjacent to the lake. Coarse fish dominate the fishery with kokanee and rainbow playing a minor role. The lake is in a eutrophic state, due mainly to phosphorus originating from traditional farming practices in the San Jose River watershed. The existing poor water quality limits drinking water use, recreation and fisheries production. Recently, overwintering of cattle away from the San Jose River has reduced phosphorus loading to the lake. A major source of phosphorus at this time is internal recycling from lake sediments. This problem could be corrected by measures such as lake aeration, iron addition to the lake or liming. Further progress in managing livestock is also necessary in the long-term to keep phosphorus levels down. The provisional water quality objectives for phosphorus, chlorophyll-a and dissolved oxygen provide an achievable goal for future lake water quality, provided some form of lake and river restoration is successfully completed. How such restoration might be implemented is beyond the scope of this report. |
