Water Quality Improvement Project
Pipers Creek is a 1.4-mile long urban stream located in Seattle, Washington.
Most of the creek is contained within the boundaries of Carkeek Park, and empties
into Puget Sound. Upper tributaries to the creek are located in residential
neighborhoods of Seattle and include Venema and Mohlendorph creeks.
Water quality issues
Pipers Creek was found to be impaired with fecal coliform bacteria. Monitoring
showed that the potential sources of bacterial contamination to the creek are
typical of urban watersheds in the area. They were identified as pet wastes;
combined sewer overflows at the treatment facility and North Beach Pump Station;
leaking sewer pipes; failing septic tank systems; and a local duck pond.
Status of the project
Ecology, along with local citizens, agencies, and special interest groups,
developed a total maximum daily load (TMDL) that detailed the sources of the
fecal coliform bacteria, and contained a plan to reduce the fecal coliform
inputs into Pipers Creek. The Environmental Protection Agency (EPA) approved the
TMDL in March 1993.
A watershed action plan was developed for Pipers Creek. Its purpose was to
formulate a coordinated program of effective actions to prevent and decrease
nonpoint source pollution in the watershed. It detailed activities aimed at
public education; improving the regulatory program; the operations and
maintenance program; and the public works program. Difficulties in
dealing with nonpoint source pollution resulted in public education as an early
implementation element from the Watershed Action Plan.
In June 2003, Ecology published the results of effectiveness monitoring done
on Pipers Creek. The TMDL required that adequate monitoring be conducted to assess progress in
achieving both the TMDL and Watershed Action Plan’s goals. Water quality
sampling was conducted bi-weekly or monthly by both City of Seattle and King
County in the Pipers Creek watershed from 1993 to the present. The data indicated that fecal
coliform concentrations continue to exceed both parts of the water quality criterion at all
Pipers Creek sites.
Ecology currently funds the Venema Natural Drainage System project with
Seattle Public Utilities (SPU). The project is located in the upper Venema Creek
basin in a dense urban neighborhood in North Seattle, tributary to Piper’s
Creek. Both Venema and Piper’s Creek are impacted by high stormwater flows, and
Venema Creek is particularly sensitive to stormwater impacts due to its
underlying geology and lack of grade controls. Both creeks are 303(d) listed for
fecal coliform bacteria. Seattle will construct a series of bioretention and
conveyance swales with underlying pipes, and use underground injection control
for some stormwater. The project will provide flow control and water quality
treatment for the approximately 81-acre Venema Creek basin draining to Venema
Creek by 2015, meeting water quality goals of 80% total suspended solids removal
and 78% annual runoff volume reduction.
Pipers Creek Fecal Coliform Bacteria Total Maximum Daily Load (Ecology
Effectiveness Monitoring for Fecal Coliform Total Maximum Daily Loads in
Pipers Creek (Ecology publication)
WRIA 8: Cedar-Sammamish-Lake Washington Watershed Information (Environmental Assessment
Back to top of page
WRIA: #8 (Cedar-Sammamish)
# of TMDLs:
Fecal Coliform - 1
TMDL approved by EPA
Department of Ecology
3190 160th Ave. SE
Bellevue, WA 98008-5452