concept and constraints

I spent much of this afternoon reviewing documents for a proposed small stream restoration project. Although my task is primarily endangered species review for a project that was designed by others several years ago and is now approaching construction, it's always enjoyable to see how others worked through their thought process; especially when I know some of the people involved. I really enjoy the conceptual design end, and this project is fairly elegant.

The concept report discusses four alternatives, all of which were reviewed by various technical folks as well as state and federal agencies and a local NGO. They range from a no action alternative to one that would attempt to put hydrology all the way back to pre-disturbance conditions, as nearly as possible.

That extreme build alternative is of course rarely viable. In this case it would flood large areas at high tide, including adjacent landowners not involved in the project. It would render large areas unusable for their present purposes, which would probably cost the support of landowners who are currently cooperating with the project. In short, it would most likely result in the death of the project because the economic and social costs would not be politically viable.

Instead, an alternative is moving forward that partially restores hydrology, but limits the inundation area. This meets the primary project goals of improving sensitive species habitat, improving sediment transport and water quality, and keeping flooding within acceptable limits. It would actually reduce precipitation related flooding by increasing channel width and storage area. It's more expensive, but still feasible.

This is the elegant part. The design accomplishes all of the project goals, which can be a challenge when some of them aren't necessarily mutually compatible. I'm impressed because the designers managed to restore enough of the ecological processes to allow the watershed to function with minimal long-term maintenance while keeping enough political support to be permitted and built; it's one of those permit processes, under Section 7 of the Endangered Species Act, that I'm currently working on.

The downside is that, as so often happens, there are areas in the upper watershed which are slated for future development and are outside the influence of the project team. So depending on how those places are designed and built, there's a risk of a restored stream increasing in function and quality for a while, and then slowly degrading in different ways as upstream watershed runoff rates and sedimentation increase and water quality input decreases.

Short of controlling an entire watershed, which is quite rare, I'm not really sure how to protect against this. I've seen a few examples of conservation easements being put in place early to buffer streams, but when upstream lands are privately owned, the stars really need to align for this to happen, it needs to somehow be in the interest of those landowners to cooperate. If there are a few larger landowners and all of them agree, it can work. If an area is already subdivided and there are hundreds of owners, the challenges multiply.