Lake will start to receive alum treatment Monday

Doses of alum will be applied to Canyon Lake’s Main Lake, East Bay and North Ski Area beginning Monday and will continue every day until wrapping up on Friday.

The treatment, overseen by the Lake Elsinore & San Jacinto Watersheds Authority, was originally scheduled to be applied last month, but was postponed because of Canyon Lake waterflows. The watershed authority said the waterflow “event” has ended, thus paving the way for the rescheduled application.

The authority last applied the alum in October and April of last year. This will be the 19th time over the years that it has overseen the alum application in Canyon Lake.

The spraying schedule is subject to change, but it is anticipated the Main Lake will be treated on Monday and Tuesday, the Main Boat Ramp area and the west end of East Bay on Wednesday, the rest of East Bay on Thursday and the North Ski Area on Friday. The boats will be out each day applying alum from 7:00 a.m. to 4:00 p.m.

The water authority will be spraying the treatment from its boat as it covers the predetermined areas of the lake, which will remain open during the entire treatment process. Recreational users will experience little disruption during treatment application and implementation.

Alum, the method selected to provide the best results for Canyon Lake, has a proven track record of success and is safe to both humans and aquatic life, Mark Norton, Authority Administrator of the LESJWA, said.

Drinking water quality will not be affected by any of the treatment options. Canyon Lake will remain open during the entire treatment process.

Alum binds with phosphorus in the lake water, drops the nutrient to the lake bottom and thereby reduces algae growth in the lake, Mark said.

Canyon Lake water mostly comes from stormwater runoff from the upper watershed each year that has high levels of nutrients that hurt water quality and threaten aquatic life.