Mercer Island's Streams

 

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Condition of Our Streams

The City of Mercer Island tests our streams on a regular basis.  The data show that our streams are the worst in the county.*  The Benthic Index of Biotic Integrity (BIBI) is a measure of stream health.  It was stated that "Mercer Island sites rank among the lowest countywide using this (BIBI) biological indicator.*"  During storm events our streams exceed the maximum allowances for contaminants.  See the Mercer Island Reporter article about polluted lake sites around the island.

Control Water Runoff

During major storms,  the island's watercourses exceed the allowances for contaminants, carrying more pollutants than does farm runoff.  Homes and yards are the major sources of this pollution.  As homeowners, we must take individual responsibility for reducing pollution in our community.  Recent studies of Seattle area preschoolers have shown
 

What Can We Do?

·         Reduce herbicides, pesticides and fertilizer that get into Lake Washington and on to your children and pets.  Since we live on and island, everything we put on the ground eventually ends up in the lake. 

q       Do not use "weed and feed" fertilizers.

q        Use organic fertilizers to improve soil health.  A healthy soil grows healthy plants.

q       Use mulching mowers so the clippings feed the lawn, this reduces the need for fertilizer.

q       Restrict the use of pesticides.  Plant a garden that attacks birds and they will eat pests and caterpillars.  However, 98% of insects are beneficial.   Pesticides do not differentiate between beneficial and bad insects they kill them all.
 

·         Do not wash your car where the detergent and water will run into a stream or the lake.   

·         Repair vehicle oil leaks.  A small amount or oil creates a large oil slick.

·         Create "water gardens" to capture the water from your down spouts and other impervious surfaces so water can percolate into the ground and recharge ground water rather than flow directly into the lake. When the island was covered with a forest less that 1% of the rainfall would have entered the lake as surface runoff.

·         Never dump anything into storm drains except clean water.  Mercer Island  has no storm water treatment.  It just flows, untreated and unfiltered, into our streams and into Lake Washington. 

·         For waterfront and streamside homeowners, create a soil swale and plant it with native trees and shrubs between your grass and the water.  This native plant buffer will filter runoff before the water flows into the stream or lake.  You can still have views with a good planting design.  For lakeside dwellers, this plant buffer will also reduce geese coming up onto your lawn.

Visit http://www.savingwater.org/ and learn more about saving water in your home and garden.

*2001 Annual Report for the City of Mercer Island: Waster Quality Monitoring un Five Drainage Basins:  Numbers 6, 19, 26, 29 and 32

PESTICIDE WARNINGS

The use of pesticides near salmon-bearing rivers and streams in the Northwest was banned January 22, 2004 by a federal judge, who also required retail stores in urban areas to post warnings about the most commonly used and potentially dangerous chemicals.

The ruling, which covers Washington, Oregon and California, was hailed by environmentalists, who cited research showing that pesticides are washing into streams and that even low levels can harm protected salmon runs.

Pesticide producers must provide warnings that salmon could be harmed by seven pesticides frequently detected in urban streams. Warnings will be posted in stores where they're sold.

  • Carbaryl -- insecticide in products including Adios, Bugmaster, Septene and Sevin; moderately toxic to aquatic life.
     
  • 2,4-D -- herbicide in Barrage, Lawn-Keep, Savage, Salvo and Weed & Feed, Weedone; used on broadleaf weeds; can be highly toxic to fish
     
  • Diazinon -- insecticide in Gardentox, Knox Out and Spectracide; kills cockroaches, ants and fleas; highly toxic to fish
     
  • Diuron -- herbicide in Direx and Karmex; used on mosses and broadleaf and grassy weeds; moderately toxic to fish, highly toxic to aquatic invertebrates
     
  • Malathion -- insecticide in Celthion, Fyfanon and Maltox; kills mosquitoes, flies and lice; can be highly toxic to fish

    Triclopyr BEE -- herbicide in Access, Crossbow, Garlon and Redeem; used on woody and broadleaf plants; low toxicity for fish
     

  • Trifluralin -- herbicide in Trefanocide, Treficon and Trust; kills annual grasses and broadleaf weeds; highly toxic to fish and other aquatic organisms

    Source: Extension Toxicology Network