Southern California Wildfire, Harmful Algal Bloom, and Fish Kill in Lake Elsinore, CA
The Holy Fire wildfire in Southern California began on August 6, 2018 and reached full containment on September 13, 2018 with a total burned area of 35.9 square miles. Lake Elsinore lies at the bottom of several large canyons draining the burned area. Since the fire containment, the area received numerous storms of varying strength from <0.25 to 5.5 inches, totaling approximately 25 inches of rain from October 2018 through March 2019. Debris flows from the burn area deposited a large sediment delta in the lake. Shortly after the first two major storms in late November 2018 hit the area, a large fish die-off was observed in Lake Elsinore which continued through January 2019. Based on multiple lines of evidence this die-off was attributed to the Golden Algae, Prymnesium parvum, a species not previously observed at high densities in the lake. The City of Lake Elsinore embarked on a study to determine if runoff from the Holy Fire had triggered the Golden Algae bloom and subsequent fish kill. Chemistry and toxicity analyses were performed on both water and sediment samples in and around the fire sediment delta. Samples for phytoplankton taxonomy were also collected in and around the fire sediment delta, as well as during monthly routine mid-lake sampling. A comprehensive analysis of results will be presented showing the magnitude of effect on lake water and sediment quality and potential for long-term impacts.