Bringing Buried Streams into the Light

By James Laughlin, Editor

I ran across a new report from the Rocky Mountain Institute on a growing trend that struck me as both strange and interesting: the process of uncovering and restoring buried streams. It's probably not a new phenomenon to people in the industry, but it's news to me.

The report, "Daylighting: New Life for Buried Streams," was based on an EPA-funded project and includes a discussion of the potential benefits and challenges involved in restoring natural streams. It includes more than a dozen case studies on projects from around the country. Successful projects have been completed in Berkeley, Kalamazoo and Saint Paul, among others.

In the U.S., at least 20 daylighting projects have been completed since 1984 and another 20 are in various stages of development. Part of the reason is economics. As deteriorating stream and stormwater infrastructure begins to fail, communities are finding it can be cheaper to open a channel than to put new pipe back in the ground. Also, restoring a stream that was lost can garner positive attention.

As a side benefit, daylighting can improve downstream water quality by exposing water to sunlight, air, soil and vegetation, all of which help process and remove pollutants. Daylighting can also reduce flooding caused by under-capacity culverts, since an open stream typically has a wider cross-section and greater channel depth than the pipe it replaces. This is important because many storm sewers were not sized to adequately carry the extra runoff that comes with upstream development.

In many cases, daylighting projects have been done in conjunction with park development or redevelopment projects. Adding a flowing stream to a public park typically draws public support and can be cost-justified. In some cases the streams come out of a storm drain on one end of the park and go back underground on the other.

Of course there are challenges to the process. Daylighting projects can raise issues relating to ownership, maintenance and liability. Nearby neighbors may worry that the streams will attract the homeless, become a trash-filled eyesore and support rats and mosquitoes.

On the technical side, just finding the original streambed can be a problem, let alone attempting to restore any meanders or geographical features. There are also safety concerns and space limitations to consider. Impacts on the watershed must also be taken into account.

Despite the challenges, and I've only mentioned a few, the idea is appealing to me. I like things natural and like to see green spaces and flowing streams wherever possible. If you can do it for less money than replacing an aging storm drain, then all the better.

Any such project would take a team approach. Engineers would need to be sensitive to the ecological aspects of such a project. According to RMI, the projects also require a good bit of technical expertise from biologists, botanists and landscape architects. Much of the success of a daylighting project is due to the planting of vegetation along the newly restored stream banks and the creation of a setting with aesthetic appeal.

The Rocky Mountain Institute report was written by Richard Pinkham, a water resource management expert and an adjunct research scholar at RMI. The report is available on-line in PDF format for no charge on RMI's website, www.rmi.org. An illustrated, spiral-bound report may be ordered for $12 by contacting RMI at 800-333-5903.