August 30, 1999
King County is renovating a stream that currently runs through underground pipes under SR-202 (Woodinville-Redmond Rd.) and parallel to NE 124th, north of Redmond. The renovated streambed will flow from the west side of SR-202 along the south side of NE 124th to the Sammamish River.
This project will mitigate the widening of NE 124th to five lanes and two bicycle lanes, with new and upgraded traffic signals being installed. That construction is expected to be finished by mid-September, at an estimated cost of $6.5 million. The stream renovation will cost $900,000, and will open by the end of 1999.
Constructed by KLB Const. from Mukilteo, the restored stream channel will cover twelve acres of flat pastureland and cleared wetland. The property, for many years owned by the Theno family, was purchased by the County from Woodinville West Farms in Nov. 1994.
"The stream was built because it was a mitigation for the road project," said Bill Oaks, supervising engineer for the project. "We came up with a fairly innovative way to turn the area back into a salmon habitat."
The mitigation came under the Endangered Species Act. The stream runs from its headwater of Patterson Creek, by Union Hill Rd., to the Sammamish River. The stream will drop into the slough via a box culvert, which will have vegetation planted inside. With most of the streambed excavated, no vegetation has yet been planted.
"It's 1,700 feet of stream relocation, taking what used to be a ditch and making it a more natural creek, bringing in marshland and natural vegetation," said Oaks. "We're going to re-vegetate it and re-establish the water flow."
Though the stream will be populated with fish species, no eggs will be placed manually in the stream. "We just let the natural species come back in," said Oaks. Expected fish are cutthroat trout and Chinook, sockeye, and coho salmon.
As part of the mitigation, several species of wetland trees will be planted along the stream, including big-leaf maple, red alder, Oregon ash, western crabapple, black cottonwood, Douglas fir, Pacific willow, western red cedar, western hemlock, and Sitka spruce.
"The stream was once a small, free-flowing tributary that meandered into the Sammamish Valley," said Brent Lackey, Sammamish River/Lake Washington Basin Steward. Lackey said the stream underwent its biggest change in 1954, when the Army Corp of Engineers created the slough. Since then, the streambed has been little more than a ditch through which the fish would travel, piped under 124th twice. King County decided to renovate the stream rather than simply pipe it under the road.
"The fish don't do well in pipes," said Lackey. "They don't mature well and don't produce enough juvenile salmon. Pipes don't provide a healthy salmon habitat. Whenever you do road renovation in sensitive areas like this, you have to take precautions. With regard to the Bull trout and Chinook salmon, the Endangered Species Act comes into play. What we're trying to do is improve the salmon habitat."