||| FROM TOBY COOPER for THE SALISH CURRENT |||


Eurasian watermilfoil — a fast-growing, non-native aquatic plant that threatens the natural freshwater ecosystems, human recreation and domestic water infrastructure — has infested Orcas Island’s Cascade Lake, prompting the Washington State Parks authority to seek permits for control. 

The popular lake in Moran State Park doubles as the domestic water source for hundreds of households in Orcas Island’s Rosario district and the destination of choice for many of the park’s 900,000 yearly visitors. Unchecked milfoil threatens both, and the park’s administrators must decide how to protect the habitat.

Water administrators in Washington have a standing permit that allows them to assess and authorize control measures for invasive aquatic plants, explained Shawn Ultican, the designated permit officer at the Washington State Department of Ecology who is handling the park’s application. 

Under that umbrella authorization established by the federal Clean Water Act and the Water Pollution Control Act, Moran has been granted a coverage permit as of July 1. It gives Moran State Park an immediate war chest — up to $75,000 in a matching grant account — with which to design a specific battle plan against Cascade Lake’s invasive milfoil.

Moran State Park takes the lead

Lizbeth Seebacher, Northwest Region Steward for Washington State Parks, is charged with managing the mitigation program. “I am leading the way,” she said, and she and Wes Glisson of the Washington Department of Ecology found Eurasian watermilfoil in lake the last summer.

The 2023 biological survey — the first in the park since 1997 — sought data on heavy metal contamination in fish. Instead, they found milfoil. Seebacher knew they had to act. “We all care deeply about the resource,” she said.

Watercraft of any sort and even fishing tackle or footgear can introduce or spread piggybacking invasives such as milfoil and certain types of mussels, but outboard motors and trailers are by far the most significant means of transport. A team inspects a motorized craft at Lake Whatcom in Bellingham. (Courtesy CoB)

“We are in the early stages of a two-year permit,” said Glisson from Ecology’s Olympia headquarters. “As we go forward, Lizbeth will be selecting from alternatives and receiving public comment.” 

Seebacher’s alternatives, together called “integrated pest management,” include physical removal by hand harvesting, public education, biological controls and the use of chemical herbicides. 

The invasive sort

The San Juan County Noxious Weed Control Program lists native milfoils of several species as occurring in local freshwater lakes. Not all are a problem. 

The invasive species including M. spicatum were accidentally introduced into North America. Once established in a freshwater lake, milfoil spreads aggressively, forming dense floating mats, impacting fishing, swimming and boating, and shading out native aquatic vegetation. 

As milfoil out-competes native plants, the whole aquatic ecosystem is at risk. Seebacher agreed the plant’s growth can be “explosive.” 

Milfoil spreads easily from lake to lake on the hulls of boats, motors, fishing tackle, footgear or anything people carry with them. “Any tiny fragment immediately grows into another plant,” said Jason Ontjes of the noxious weed control program. “It continues to spread from there.”

Your drinking water

Dan Burke, general manager of the Eastsound Water Users Association (EWUA), confirmed that Cascade Lake supplies drinking water for 500-odd households in the Rosario district, plus Rosario Resort. The EWUA is the billing agent for Washington Water, which, along with Rosario Resort and certain private parties, owns the water rights.

Burke is aware of the need for milfoil controls. “We are seeking details on the park’s control strategy,” he said.

“Approvals by all water rights holders are needed as a condition of the permit,” said Seebacher. “The public will be notified and comments received during this process, as required by our permit.”

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