In early 2007, the District was informed by the Corps of Engineers that the channel was deficient in its maintenance because accumulated sediment had not been removed. The difficulty in getting permission to remove this sediment (and the environmental impacts from dredging) was the reason for instigating the overall Restoration Project and the partnership with the Corps. But the Corps has many sections and their missions sometimes conflict with each other. While the district was partnering with the Corps on a restoration solution, another section of the Corps demanded the channel be dredged quickly!
The District negotiated with the Corps and developed a project that would minimally meet the Corps needs, not derail the ultimate Restoration Project, and could be completed within the Corps’ timeframe. This was the 2007 Interim Protection Measures Project. Scope of Project Using data gathered for the overall Restoration Project, the Interim Protection Measures Project was designed to regain flood capacity lost to mud, sediment, and debris that had accumulated in the channel and from levees that had settled over time.
Specifically, the project included removing over 200,000 cubic yards of sediment from the floodplain benches on each side of the low flow channel.
Extent of Project This removal of sediment, otherwise known as desilting, occurred from the Burlington Northern Santa Fe Railroad crossing, upstream past the Central Contra Costa Sanitary District (CCCSD) treatment plant and the Tesoro Oil Refinery, up past Imhoff Drive, Highway 4 and Marsh Drive, and extended up to the confluence of Walnut Creek and the Clayton Valley Drain.
Because of environmental issues, no sediment was removed downstream (north) of the BNSF Railroad.
Interim Protection Measures Project Maps Click here to view a project overview map. Click here to view a watershed map showing the project location. Click here to view a smaller, lower resolution version of the watershed map.