Seattle Parks and Recreation applies for coverage permits from the Washington State Department of Ecology

Eurasian milfoil

Eurasian milfoil

Seattle Parks and Recreation (SPR) is seeking coverage through Washington Department of Ecology permits to use aquatic herbicides to systemically control certain aquatic weeds. The goal is to improve water quality by managing both the invasive water lilies and milfoil at City’s freshwater beaches, swim areas, moorages and high use recreation sites. This is part of SPR’s integrated weed management plan for Eurasian milfoil and other regulated aquatic weeds.

Permitted use of an aquatic herbicide is endorsed by Washington Department of Ecology as a systemic solution to control specific aquatic weeds that impact recreation and water quality. The permit will cover the City owned properties on Lake Washington, Bitter Lake and Ship Canals –Lake Union.

Fragrant white water lilies

Fragrant white water lilies

Bellevue, Kenmore, Kirkland, Lake Forest Park, Medina and Renton have current permits from Ecology. The permit allows the discharge of a specific list of herbicides provided permit conditions are met, however, the herbicides currently anticipated for use are: Glyphosate, Imazamox, Imazapyr and Triclopyr TEA.

More information about the permit

Questions and comments during the permit process should be addressed to the Department of Ecology, Water Quality Program, Attention: Aquatic Pesticide Permit Manager, P.O. Box 47600, Olympia, WA 98504-7600 or

Parts of Gas Works Park to close for Department of Ecology sediment work

Over the next two months starting Wednesday, March 6, small sections of Gas Works Park will be closed to the public as environmental crews continue an ongoing investigation of sources of contamination along the park on Lake Union.

The State Department of Ecology (Ecology) oversees the work under a March 2006 legal agreement between Ecology, the City of Seattle and Puget Sound Energy (PSE). The soil and groundwater study will help in the cleanup of contaminated lake sediments by gathering information on the effect of underground contamination from the upland (on-shore) area on sediment (lake bottom mud) in Lake Union.

Details on this project and other cleanup work at Gas Works Park are available on Ecology’s website at

Contractors hired by PSE will perform soil borings and install monitoring wells to study soil and groundwater conditions 10 to 50 feet below the ground surface. Preliminary field activities have begun and drilling activities are scheduled to begin on March 18, 2013.

Park users can expect to see track-mounted drilling rigs that will push probes into the ground in up to 80 locations in the park. A 50-foot area around each drilling location will be closed to the public while drilling takes place, then reopened. An area for staging equipment will be signed and fenced.

A half acre field just north of the park’s Play Barn will remain closed to the public until late spring to allow new turf grass to take root.

Once the sampling and monitoring work is completed, the results will be analyzed and incorporated into a Draft Remedial Investigation/Feasibility Study Report (RI/FS). The RI/FS will describe the findings and outline potential cleanup options, and will be available for public review and comment.

BackgroundGas Works Park is a 20-acre park located at the north end of Lake Union. From the early 1900s until 1956, gas companies operated a plant at the site that converted coal and oil into manufactured gas. A tar refinery also operated at the site, refining materials obtained as a byproduct of the gas manufacturing process and producing tar-based coal products.

The Park underwent an environmental cleanup in 2000-01 and in 2005, when most of the park was covered with two feet of clean topsoil placed over a protective barrier. The historic gasification plant metal structures were preserved in place. And groundwater remediation was conducted from 2001 through 2006.

Investigation of the sediments offshore of the park in Lake Union has indicated the presence of contaminants. The upcoming work includes evaluation of the upland areas for impacts on the sediments. The results of the work will identify the nature and extent of impacted soil, groundwater and sediment and help identify potential cleanup solutions.

Parts of Gas Works Park Will Close Temporarily

Portions of Seattle’s Gas Works Park and parking lot will be closed to the public for several weeks starting Sept. 27, as Seattle Public Utilities (SPU) continues its ongoing investigation and evaluation of sediments offshore of the park. 

The environmental testing—involving heavy equipment drilling of groundwater monitoring wells—is scheduled to take place weekdays during daylight hours. It will be noisy at times, and Puget Sound Energy’s contractor will monitor sound levels. There will be vehicles entering and leaving the park during the testing. 

Gas Works Park, including the snack bar and restrooms, will remain open during the work, but park visitors will be restricted from areas where drilling activities are taking place and areas where equipment is stored. 

The City of Seattle (under the lead of SPU) and Puget Sound Energy are studying the park and the adjoining lake bottom to gather information needed to clean up contamination left in Lake Union’s sediments by the manufactured gas plant and other industrial facilities that once operated at the site. The investigation and subsequent cleanup of contaminated offshore sediments is expected to take several years. 

More information about this cleanup is available on the Washington State Department of Ecology’s website:  

In addition to providing a reliable water supply to more than 1.3 million customers in the Seattle metropolitan area, SPU provides essential sewer, drainage, solid waste and engineering services that safeguard public health, maintain the city’s infrastructure and protect, conserve and enhance the region’s environmental resources. 

Seattle Parks and Recreation operates 26 community centers, 10 community pools, and four environmental learning centers, and manages more than 6,200 acres of park land. Parks’ mission is to build community through people, parks and programs.