To: Honorable Mayor and Members of City Council
From: Phil Brun, Utilities Director
Prepared By: Joy Eldredge, Deputy Utilities Director
TITLE:
Title
Report on Lake Hennessey and Milliken Reservoir Watersheds after Hennessey and Glass Fires
LABEL
RECOMMENDED ACTION:
Recommendation
Receive report on potential impacts to the Water System from the recent wildfires in Napa County.
Body
DISCUSSION:
The City of Napa Utilities Water Division owns two watersheds and operates three surface water treatment plants to provide potable drinking water to more than 80,000 customers in the City of Napa, unincorporated Napa County, and surrounding communities. Our watersheds dictate the quality of the water that fills our drinking water reservoirs and the level of treatment that is necessary to ensure clean, safe water to our customers.
On August 16, 2020 the Hennessey LNU complex fire started less than one mile from Lake Hennessey due to lightning strikes on Hennessey Ridge. The fire spread south and east away from the reservoir and into the area that drains into Sage Creek, the third largest tributary that feeds Lake Hennessey. The fire burned a total of 9,000 acres of the 32,800 acre watershed that recharges our Lake Hennessey drinking water supply. The fire also burned 800 acres within the farthest reach of the 6,000 acre Milliken Watershed.
On September 27, 2020, the Glass Fire started just north of the Hennessey watershed. The predicted shift of the winds to Northwest winds had the potential to blow embers and or cause the fire to spread southeast toward our treatment facilities. Staff worked across divisions and departments to put forth an outstanding effort to harden our treatment and conveyance facilities should the fire spread to our property. In the end, our treatment facilities and the watershed were spared from the Glass Fire.
After the wildfire was contained, the CalFIRE Watershed Emergency Response Team (WERT) assessed the post-fire geologic a...
Click here for full text