Creek Daylighting: A Stormwater Management Trend

October 28, 2009

How a city manages its stormwater affects everything from the water quality of local rivers, lakes and estuaries to flooding and combined sewer overflows. Creek "daylighting" (freeing streams from culverts and paved channels) is an increasingly popular method for state, county, and local governments to improve stormwater management and water quality.

California is a hotbed of creek daylighting activity. But major projects have occurred in other states around the country.

Whether or not creek daylighting projects are already in the works near you, if you're in or near an urban area, there are almost certainly channelized creeks, and perhaps overburdened stormwater (or combined) sewer systems. Examining options for creek daylighting, or just asking "why is this creek channelized?" can reveal a compelling array of issues about how people relate to their local environment.

Creek daylighting mainly means restoring streams to a more natural state so that more stormwater gets absorbed and gradually released by soil and plants. This not only slows and controls stormwater surge; it also helps remove pollutants from water — thus improving downstream water quality. Creek daylighting projects also can expand wildlife habitat and provide the aesthetic benefit of more greenery.

USGS "WaterWatch" maps are a useful starting point to understand patterns of local flooding events. They are also available in Google Maps format.

Once you know where the local flooding happens, look upstream in the watershed for channelized creeks.

Often creek daylighting becomes an especially attractive option when cities are faced with the expense of having to repair or replace crumbling culverts or channels — or with fines for violations from combined sanitary and stormwater sewer overflow events.

Current projects:

The Wikipedia page for stream daylighting offers many useful leads for projects and resources.

Successful creek daylighting projects aren't exactly park-like — and for that reason they can conflict with expectations of nearby residents and sometimes lead to controversy and backtracking after they've been put in place. This means the local news value of creek daylighting often can recur or even increase months or years after a project is done.

In order to get full water quality and management benefits, a daylit creek must be surrounded by a rich "understory" (shrubs and plants growing at ground level), which help absorb and process a significant volume of stormwater. However, dense understories usually look quite unruly and visually impenetrable. Nearby residents sometimes complain that they are unsightly (perhaps a little "too natural") and provide a haven for insects and rodents as well as vagrants and unsupervised teens.

Also, daylit creeks take up more space than channelized creeks. Strenuous local battles sometimes erupt over these land use changes. For instance, the 2006 daylighting of Ravenna Creek in Seattle involved the controversial relocation of a ballfield.

Talk to community groups and leaders about personal reactions to daylit creeks. How has it affected quality of life? Bring your video camera, capture personal stories and mixed emotions.