From 9K acres to just 6.4: WA continues annual battle against ‘aggressive’ invasive weed

Washington’s annual treatment of Spartina, an aggressive invasive weed in the state’s important estuaries, will begin on June 1 and continue through November.

The Washington State Department of Agriculture (WSDA) Pest Program will carry out surveys and eradication efforts for Spartina in several areas, including Grays Harbor, the Hood Canal, Willapa Bay, the Puget Sound, the north and west sides of the Olympic Peninsula, the San Juan Islands, and near the mouth of the Columbia River, WSDA announced.

Invasive weed threatens WA’s ecosystems, shellfish industry

Spartina, commonly known as cordgrass, can disrupt the ecosystems of native saltwater estuaries. If left untreated, Spartina outcompetes native vegetation and converts ecologically healthy mudflats and estuaries into solid Spartina monocultures, according to WSDA.

As a result, the important habitats for salmon, forage fish, invertebrates, shorebirds, and waterfowl are lost. Flooding threats also increase, and Washington’s shellfish industry is negatively impacted.

Lately, Spartina has invaded some valuable salmon restoration sites in North Puget Sound. A major goal of the 2026 eradication effort will be to address Spartina’s spread into these sites and to devise eradication solutions.

WSDA noted the Spartina eradication effort has been highly effective as infestations have been reduced from a high of more than 9,000 solid acres in 2003 to 6.4 solid acres in 2025.

Spartina was also successfully eradicated at 80 sites, although there is significant work left to be done. The remaining Spartina plants are spread across 122 sites, meaning 60% of Washington’s 202 infested sites have yet to be eradicated.

“Our goal is to eradicate Washington’s remaining Spartina infestations, protecting important habitat for salmon, waterfowl, and shellfish,” said Chad Phillips, WSDA’s Spartina Program Coordinator. “The Spartina Eradication Program protects our state’s most productive estuaries and shoreline habitats. This year, with our project partners, we will continue the challenging work of finding and removing the thousands of Spartina plants that remain in the Puget Sound and along Washington’s coast.”

Project partners to survey thousands of acres, hundreds of miles of shoreline this season

This season, project partners will survey thousands of acres of saltwater estuaries and hundreds of miles of shoreline. These groups typically dig out small infestations by hand and utilize herbicides at larger infestations.

WSDA has served as the lead state agency for Spartina eradication since 1995, in a joint effort amongst local, state, federal, and tribal governments; universities; interested groups and private landowners. Last year alone, the partnership identified and treated more than 29,000 individual Spartina plants.

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