Lower Walnut Creek Restoration Project

I decided I'd look close to home (I grew up in Walnut Creek) to see if there were any active restoration projects around the creeks. There are a lot of "Friends of the __ Creek" organizations and communities frequently have creek clean-up days (I went to some of those when I was in high school), but I was curious if there were any specific projects that were actually involving changing hydrology or habitat. I believe Molly was working on a project related to this so I thought it might be of interest (and please feel free to add to what I have here).

As it turns out, there is a portion of Walnut Creek (the creek, not the city) in Martinez which was channelized in the 60s by the Army Corps of Engineers, and since then silt has built up in that channel, which poses an interesting issue: some of that deposited sediment has become habitat, but it has reduced the channel's ability to control floods, which means the Corps is insisting that the Flood Control District (which is a part of the Contra Costa County Public Works department) take an action to come into compliance.

One thing in the favor of the Flood Control District, in my opinion, is that they are taking into account the ecological values that the deposited sediment has. Unfortunately, the Corps is forcing them to do something about the lack of flood control. So there are two parts to the restoration plan: first, they are going to do something in the short term to appease the Corps, which will involve some removal of sediment or 'desilting' (the "2007 Interim Protection Measures Project"); and second, they are in the planning stages of a process that will try to come up with a solution which will work better than the existing ones. As of this year (2010) they are in the stages where they are doing a lot of hydrological modeling to determine what kind of sediment loading can be expected (something that was underestimated by the Corps back when they channelized the creek in the 60s). "The current emphasis is to develop a watershed-wide sediment transport model to determine the source and volume of generated sediment and develop a revised channel design that either allows the sediment to settle out in non-environmentally sensitive areas or to encourage the sediment to pass through the channel out to the bay. " The Flood Control District repeatedly notes that funding for this project is partially provided by the Corps, and that funding level fluctuates wildly over the years.

There is some thought about recreational values as well, including a proposal to extend the developed part of the Iron Horse Trail (a bike path which currently goes from Dublin/Pleasanton Bart up through Concord) further north along this section of the creek (ultimately all the way to Susuin bay). The Flood Control District has also generated a report on the potential for chinook and steelhead salmon spawning along these lower reaches of Walnut Creek, and the report "confirmed the presence of redds in the bed of Lower Walnut Creek, but found very low survival of eggs and fry," indicating that scour and fines (the sediment) may have respectively washed away or buried the eggs.

My evaluation: While the overall premise of this project is good, in the sense that they are seeking ways to better understand the sediment loading and hydrology of the watershed (and they are looking at some of the watershed-level issues) and are trying to balance human needs (flood control) with ecological needs (e.g. salmon spawning), I feel that they could make more efforts to involve the communities in some of the planning. While they have described a very specific planning process (conforming to the Corps' standards for this kind of process) which includes public input, there is no indication of what the public input was at the earlier stage. The stage they state that they are now working on comes after a stage of "Public meeting / workshop to determine the project scope" but there are no documents on the project's website indicating what was determined at that/those meetings, leaving me to wonder how well that meeting was advertised, for example, and to whom. There are later stages where the public reviews the draft report on what they plan to do and there is to be a public meeting after that stage, but it strikes me as somewhat 'after the fact.'

It has been pointed out time and again that the human factor is just as important as the ecological/geological factors... while they talk about a watershed-wide sediment model, I want to know more about how human actions affect that model, e.g. development, management of the creeks upstream, etc. They mention studying the economic effects of flooding, which is something, but I didn't see anything else along these lines.

They are clearly not yet at the point where they have established criteria for success, and I hope that after they have done some hydrological and sediment modeling, they will do some ecological modeling as well to follow up on efforts like the salmon report. In fact, because they have had to de-silt parts of the channel, they could watch and see how the sediment builds up and how the community of plants and animals assembles itself in the new habitat.

Overall, it seems to me that this project has promise, and I'm glad that there's evidence that they are thinking of more than just one goal for this natural area, but I think there could certainly be more done to integrate human factors and ecological factors into this project. They aren't that far into the planning of the restoration project itself, but I'm hoping that they will do more with these aspects than they currently show evidence of doing.

Photo: from the project website, under maps and photos: photo gallery. (http://www.co.contra-costa.ca.us/index.aspx?NID=2631) Sediment removal from interim measures project.

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