Friday, October 28, 2011

Whatcom County's Newest Stormwater Feature Replaces This

Until very recently, the neighborhood adjacent to the upper reach of Silver Beach Creek, in the Lake Whatcom watershed, looked like this during a heavy rain event. Besides flooding, there high levels of phosphorus and fecal coliform documented in this area.

Here’s what the new stormwater feature looks like today. This feature includes a widened stream channel, stabilized slopes, vegetated swales, and a series of underground stormwater vaults. All together, this system will slow down the flow of stormwater, and reduce levels of phosphorus and other pollutants into Lake Whatcom.

What caused the flooding and pollution problems? The developed landscape, with houses, lawns, and streets, is largely impermeable. Before the landscape was developed, there were layers of vegetation moderating rainfall, which allowed for absorption of rain. In a forested system, phosphorus levels are moderated by biological processes in deep layers of soil. Today, the deep soil is gone. Lawns and streets are proven sources of phosphorus, and increased volumes and velocities of stormwater flows cause a multitude of water quality problems in Lake Whatcom, as well as localized flooding to homes.

As always, there's a lot to this new system that we can’t see from the photo. The system was designed by a stormwater engineer. The County negotiated with many private landowners to obtain easements. Grant funds and other sources of funding were secured, a time consuming process. Contracts were written, bids were obtained, the project was constructed, inspected, and completed for less money than was projected. I'm sure I'm leaving things out, but the result is an attractive, functional, long lasting fix that will improve water quality in Lake Whatcom, our drinking water supply. Thanks, Whatcom County!

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