Although alum treatments have continued to reduce phosphorous, numerous other factors contributed to the most recent algae bloom in Canyon Lake, says spokesperson Mark Norton, water resources and planning manager for the Santa Ana Watershed Project Authority (SAWPA).
Norton explains that warm summer temperatures, low lake levels amid the drought, high nutrient content, low oxygen in the water and tepid water movement have all combined to create a seasonal “brown algae” (another less common form of blue-green algae) bloom recently found from lake quality sampling results in the cove areas of Canyon Lake.
Canyon Lake has a long history of annual algae blooms. Although the blooms can occur at any time of the year, they usually appear when high temperatures are frequent.
Norton assures residents that, during the blooms, water in the lake remains safe for swimming, water skiing and all other recreational activities. However, because certain species of algae are occasionally unhealthful, it is advisable not to drink large quantities of the lake water, although incidental ingestion during recreational activity poses no significant health risk.
“The alum applications in the main body of Canyon Lake have done a tremendous job in reducing phosphorous, a nutrient that is a key contributor to algae growth and fish kills,” Norton says. “Based on our most recent water quality data, the overall clarity of Canyon Lake has improved. However, algae blooms still persist and come and go in the more stagnant water areas such as the East Bay coves.”
He notes that, after the initial alum application phase is complete, an in-depth effectiveness report will be prepared to evaluate what changes may be needed to meet water quality targets. The options may include further alum applications as well as possible alternative treatments such as using algaecides before the alum, particularly in the cove areas.
The initial alum program in Canyon Lake was designed to include five applications over two and-a-half years. So far, four applications have occurred and the next is set for September. The project is being funded by a state grant and by the Lake Elsinore and Canyon Lake Total Maximum Daily Load (TMDL) Task Force, which consists of cities, the County of Riverside, agriculture and dairy coalitions and other organizations in the San Jacinto River watershed.
Implementation of the alum project is being coordinated by the City of Canyon Lake, the Elsinore Valley Municipal Water District, LESJWA, the TMDL Task Force and the Canyon Lake Property Owners Association.
For more information about LESJWA, visit www.mywatersheds.com.