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Sources of Water for Lake Casitas

Lake Casitas fills primarily from the natural flow of local creeks and the Robles Diversion. In any given year roughly 1/3 of the Lake’s water comes from the Robles Diversion.

In all, the watershed that supplies Lake Casitas is nearly 35,000 acres, and the largest is the Ventura River- but only a percentage of river water can be diverted to the Lake. The rest ensures water for downstream users and environmental purposes as outlined by the Federal Government.

Design of the Robles Diversion

The diversion is basically a large canal brings water from the river to the lake.  It is made up of several elements.

As water enters the canal, it passes through debris cleaning screens to ensure woody debris and other elements flowing in the river don’t clog up the canal on its way to the Lake.

The channel flows approximately 7 miles to lake casitas and enters near Santa Ana Creek to make the largest entry point for incoming water.

Going back up to the forebay, there is an additional flow that goes downstream- the fish ladder. This structure allows endangered steelhead to migrate unobstructed back upstream and spawn in the waters of the upper Ventura River.

 Which Government Agencies are involved? 

The National Oceanic and Atmospheric Administration's National Marine Fisheries Service governs the requirements for fish passage and Casitas is bound to their biological opinion.  We must ensure flow for environmental purposes in balance with our need to divert water for storage in the Casitas system.

Casitas is always working with Federal regulatory agencies to maintain the delicate balance between protecting our environmental resources and ensuring water security for our customers.  The diversion is a critical part of the Lake’s storage infrastructure and during this drought are working to be sure the diversion is open when the water is flowing.

Daily Robles Diversion Measurements 

Data below regarding flows into Lake Casitas as measured at the Robles Diversion are updated daily.

As of October 1, 2022, Year-to-Date  totals are based on  the Water Year (October 1 - September 30).

 **This data is presented for information only. Data are provisional and subject to revision.**
Additional Note: Full lake capacity (100%) is achieved at lake elevation 567.00