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Statement of Purpose


Removing Matilija Dam:

Final Design:

Feasibility Study:

Early Progress:

Background Information:

About the Matilija Coalition:

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Matilija Dam Ecosystem Restoration Feasibility Study

Baseline Conditions Report

The Baseline Conditions “F3 Report” and other technical studies may be accessed at

The following is a summary of the findings from the baseline conditions studies conducted from June 2001 to October 2002:

Flooding: An examination of the historic flood records on the Ventura River revealed that Matilija Dam has never controlled peak river flows, and some localized flooding continues to occur with the dam in place. Levees have reduced the flood risk for much of the existing floodplain development.

Sediment: Surveys of the reservoir indicate that it contains approximately six million cubic yards of sediment, including about 1.8 million cubic yards of beach quality sand. While the sediments tested clean, much of the beach sand is intermixed with fine sediment that is not suitable for direct use for beach replenishment. Studies estimate that the reservoir will completely fill with sediment by 2020, but will continue to trap sediments until 2030, when some coarse sediment will begin to pass over the dam. At that time the impounded sediments will total over nine million cubic yards.

Habitat: The sediment trapped by Matilija Dam has significantly degraded the downstream river and coastal habitats. Surveys reveal that, downstream of the dam, sediment-starved “hungry water” has eroded the riverbed so that it now suffers a deficit of almost two million cubic yards of sand, gravel and cobble. The historically broad floodplain with many braided channels has become a single channel cut into the river bed. Sediment reduction has exacerbated beach erosion from the mouth of the river to the Ventura harbor. High quality habitat still exists in the upper watershed, but remains disconnected from the river and coast. Arundo donax, or giant reed, degrades the habitat value, and is spreading throughout the reservoir and floodplain terraces downstream.

Dam: Structurally, the dam suffers from extensive “Alkali Silica Reaction,” a chemical reaction that weakens the concrete. Despite this problem, there are no structural modifications needed for the dam to remain adequately stable for next the 50 years.

©Matilija Coalition, All Rights Reserved, 2002.
Page last updated: May 2002