Date: January 1, 2006
Community and Government Affairs
City of Lake Forest Park
206-368-5440
News Release
Update on the State of Our Streams (part two)
Click to read part one
The Lake Forest Park StreamKeepers previously reported on two types of stream water monitoring: basic chemical characteristics and fecal coliform.
The results of a third type of stream testing are now in – the analysis of the types of small creatures that inhabit our streambeds. These tiny creatures, called macroinvertebrates, include insects, worms and mollusks. They are important in our streams because larger animals such as fish, crawdads, and salamanders depend on them for food.
BIBI - A stream health profile
The formal name for this testing is the Benthic Inventory of Biological Integrity, or BIBI for short. It was developed by a UW Fisheries professor and is widely used in the Northwest as an important measure of overall stream health. StreamKeepers collect BIBI samples for the City in the fall, and send them to a BIBI-trained biologist. By analyzing the different types and numbers of creatures collected from a small area of a streambed, we get a broad profile of stream health, and can rate our streams on a scale from Very Poor to Excellent.
In 2005, four BIBI samples were collected, two on McAleer Creek and two on Lyon Creek. By the BIBI rating system, two of the four samples were classified Poor, one Very Poor, and one Fair. While BIBI monitoring is in the early stages in LFP, these results should sound a strong warning about the fragile biological health of our streams.
What’s the problem?
A good case can be made that storm water run-off, with its resultant soil erosion and introduction of pollutants into the streams, is the main cause of impaired stream health. Increased erosion contributes to low BIBI scores, since many macroinvertebrates live in the spaces around stream rocks, and are literally squeezed out by sediment deposits.
With the reduction of wetlands and flood plains over the years, our streams have become susceptible to heavy erosion during extended periods of rain. In many locations, streambeds are undergoing fundamental changes: sand and silt are covering over some graveled areas (spawning habitat), and other spots are being scoured to the base rock.
What we can do to improve stream health:
- Maintain and restore significant buffers to slow water flow and reduce erosion.
- Minimize polluting chemical run-off from our lawns, driveways, and roads.
- Remove invasive plants that alter stream habitat, and restore natural vegetation.
- Stream testing – January 21
The LFP StreamKeepers website www.lfpstreamkeepers.org has more information about stream monitoring. The next stream testing is Saturday, January 21, 9am-11am. Volunteers gather in the lower level of the mall. New StreamKeepers are always welcome!
