Dam Removal for Stream Mitigation Credit

As one of the most pure forms of stream restoration, one would think that dam removal would be a highly sought after source for stream mitigation credit. However, in most jurisdictions, that is not the case.

People have been altering streams and rivers across the United States for hundreds of years. One of these alterations has been the building of thousands of dams. There is estimated to be over 75,000 dams across the United States. Many of these dams have well surpassed their usefulness and are obsolete, safety hazards, and block aquatic organism passage. For these reasons many dams have been targeted for removal, and American Rivers estimates that almost 1,150 dams have been removed in the last century. With numerous benefits, dam removal is one way to truly restore streams and aquatic ecosystems from highly impacted, unconnected lotic environments to naturally flowing streams and rivers. In many states, there is a long list of dams that have been targeted for removal and would benefit anadromous fish and endangered species, as well as restore natural stream functions. While there is no shortage of potential sites, these projects can be slow to implement due to limiting factors including funding and permitting hurdles.

One tool to help overcome these challenges should be generating stream mitigation credits with dam removal projects. Stream mitigation credits are traditionally generated via restoring, enhancing or preserving streams and are part of the compensatory mitigation mandated by the EPA. It can easily be argued that dam removal is the most effective method of stream restoration there is, but since it doesn’t follow a traditional approach, the process and method of generating mitigation credits with these projects is not straight forward. To add to the challenge, stream mitigation is managed differently in each state, with multiple regulatory agencies contributing to the way that credits are generated.

Generating mitigation credits with unconventional methods is not unprecedented. Some U.S. Army Corps of Engineers (USACE) districts have been experimenting generating credits with best management practice (BMP) type projects or other unconventional methods. There have also been a small number of jurisdictions (North Carolina, Ohio, Pennsylvania and Washington, D.C.) where dams have been removed to generate mitigation credits. The projects in Washington, D.C., were a part of the mitigation package associated with building the Woodrow Wilson Bridge in the mid-2000s and did not generate a specific number of credits for each project.

The other three jurisdictions have generated credits that could be used just like credits from traditional stream restoration projects. North Carolina implemented a small number of dam removal projects to generate mitigation credits based on guidance developed by the Wilmington District USACE. Since those projects were constructed, the USACE has rescinded this guidance, possibly because they were not comfortable with the credit amounts that the projects were generating. In Pennsylvania, there is no established guidance, but projects routinely generate credits. For these projects, the amount of credit is determined on a case-by-case basis, usually related to the expected ecological lift associated with the project. In Ohio, the credit is generally related to the linear footage of channel that had been backwatered and is converted back to free flowing.

These examples demonstrate that generating mitigation credits from dam removal is viable in today’s regulatory environment and should be an available option. They also show how there are a variety of ways to go about this, and that it is not a one size fits all process.

It is important to recognize that dam removal projects are not always straight forward and do not compare well to traditional stream restoration projects that may follow a strict set of guidelines and check all the boxes on an official list. As mentioned earlier, dam removal may be the most direct form of river restoration there is, but since these projects do not fit the mold of traditional stream restoration, there are numerous questions or concerns that must be dealt with. Some of these issues may have to do with perpetual conservation easements, monitoring methodology, riparian buffers or bank stability. Although none of these issues should prevent these projects from generating mitigation credits, we cannot ignore the fact that these will be stumbling blocks for many regulators. In districts where this has never been done, there may need to be a gradual period where the project ‘issues’ cause lower credit ratios so that regulators are eased into this process.

In many states, stream mitigation credits can be generated and sold, either through in-lieu fee programs or mitigation banks. In this way, generating and selling credits associated with stream restoration is a way of self-funding projects and in many cases is a for-profit business model. The same process should be transferable to dam removal. We should consider that generating mitigation credits can be one of a combination of tools for funding projects. If a site does not generate enough credits to fully fund itself, that gap in funding can be bridged with private grants or other sources that are funding dam removal projects now. By starting this process we can create a new project driver that will encourage more dam removal and bring about positive change to the health of our streams and rivers.