Thursday, July 9, 2020

Matilija Reservoir Drained

Matilija reservoir was drained over the 4th of July weekend.    According to county staff, this was done in response to safety concerns, as identified by the state Division of Safety of Dams (DSOD) as well as the liability resulting from recreational use of the dam site. The 12" valve controlling the dam outlet was opened on the morning of Wednesday, July 1, releasing flows of approximately 30 cubic feet per second downstream.  The valve will remain open maintaining the reservoir in a drained state until the winter rains.   

Images of the drained reservoir reveal the degree of additional sedimentation since the Thomas Fire, which has reduced the storage capacity to less than 150 acre feet.  As illustrated in the photos below, the initial flush released relatively clear water, but downstream water quality degraded as flows began to cut a channel through the sediment.  The channel evolution is documented in the overview photos of the reservoir. 


Prior images on this blog:

In the news:
Matilija Reservoir Drained, Ojai Valley News, July 17, 2020 (see full article below)
How Oroville Is Changing Dam Safety in California, Public Policy Institute of California, March 28, 2018

Reference:




Matilija Reservoir, July 2, 2020

Matilija Reservoir, July 3, 2020

Matilija Reservoir, July 8, 2020


Matilija Reservoir, July 12, 2020


Matilija Reservoir, July 15, 2020


Matilija Reservoir, July 22, 2020

Matilija Reservoir, July 27, 2020

Matilija Reservoir, August 4, 2020

Matilija Reservoir, August 12, 2020






Matilija Dam and drained reservoir,
July 8, 2020

Matilija Dam and intake to the outlet pipe,
July 8, 2020

Matilija Dam intake to the outlet pipe,
July 8, 2020





Downstream of Matilija Dam,
July 17, 2020
(courtesy S. Zach Futujma)




Confluence of North Fork (foreground) and Matilija Creek 
July 8, 2020

Camino Cielo Bridge, July 2, 2020

Camino Cielo Bridge, July 6, 2020


Ventura River at Camino Cielo Bridge
7-2-2020


Ventura River at Camino Cielo Bridge
7-4-2020




Ventura River at Camino Cielo Bridge
7-6-2020



Ventura River at Camino Cielo Bridge
7-8-2020


Ventura River at Camino Cielo Bridge
7-12-2020



Ventura River at Camino Cielo Bridge
7-17-2020

Ventura River at Camino Cielo Bridge
7-22-2020

Ventura River at Camino Cielo Bridge
7-27-2020

Ventura River at Camino Cielo Bridge
8-4-2020

Ventura River at Camino Cielo Bridge
8-12-2020



Ventura River looking downstream at Camino Cielo Bridge
7-8-2020






Ventura River at Oso trailhead crossing,
July 8, 2020







In the news:
Matilija Reservoir Drained, Ojai Valley News, July 17, 2020