Holy Fire affects stormwater quality in Southern California

The monitoring design focused on addressing one priority management question from the SMC Post-Fire Water Quality Monitoring Plan: How does post-fire runoff affect contaminant flux? The goal of the study was to assess contaminant concentration and flux by sampling stormwater runoff from the terminal end of burned catchments. The data were compared to reference sites to assess the effects of the...

The contaminant flux was calculated as the ratio of the mass loading in kilograms (kg) and the contributing catchment area in square kilometers (km2) for each storm monitoring event. Mean total phosphorus and total nitrogen flux were estimated to be between 69- and 98-fold higher from burned catchments, and total copper, lead, and zinc flux were estimated to be between 659- and...

In anticipation of the increased storm flows and sediment runoff following the Holy Fire, the District also implemented post-fire debris flow clean-up operations to improve and maintain overall debris basin capacity, capture eroding sediment mobilized by major rain events, protect downstream communities, and prevent further impacts to downstream receiving waters. The Districtʼs response...

Rebekah Guill is the monitoring programs manager at Riverside County Flood Control and Water Conservation District in Riverside, California. Garth Engelhorn is water resources senior project manager of Alta Environmental, an NV5 Company, headquartered in Long Beach, California.