Efforts to wipe out spartina succeeding

Published 9:00 pm Wednesday, June 6, 2007

CONWAY – Bill Rogers and Jerry Good couldn’t find much of what they were looking for while trudging in their boots through the muddy intertidal flats of Skagit Bay.

But that was a good thing.

The duo from the Skagit County Noxious Weed Control Board could only locate a few isolated patches of the invasive coastal weed spartina last week.

The same site, called Gallups South by the state Department of Agriculture, was overgrown with the stuff just last year.

“That’s pretty good if we can only find one patch,” said Good, standing over a lone bunch of green spartina grass.

Work crews had placed more than a hundred fluorescent flags in the same mud last summer to pinpoint plants of the then-abundant spartina, a nonnative cordgrass.

Such spartina-less experiences are becoming more common along Washington’s coasts. The Agriculture Department reports a 75 percent decline in spartina statewide since its battle against the invasive weed began a decade ago.

At its peak in 2002, the Puget Sound, Hood Canal and San Juan Islands were home to 9,000 acres of spartina. Today, state spartina coordinator Chad Phillips estimates there are fewer than 2,250.

Originally from the eastern and Gulf coasts, the invasive weed was first introduced to Pacific shorelines about 60 years ago when oysters with spartina remnants were imported. Although it’s revered for erosion control on the Atlantic, the Pacific’s expansive, flat and shallow shorelines give the grass far more space to expand – and invade.

Disruptive weed

From shellfish to floods, spartina spells trouble for many along the Pacific coast. Spartina’s extensive network of roots clump together so thickly in intertidal mud that they eventually choke out many underground aquatic species, including shellfish and small invertebrates. That means the juvenile salmon and shorebirds that depend on such small critters that normally live in mud flats lose a valuable food source.

And the coastal grass can grow so abundantly that it turns tidelands into spartina meadows that trap silt flowing out of nearby rivers. The accumulated dirt raises the tide flats elevation, thereby putting surrounding towns at greater risk during floods.

In the past 10 years, state agencies have spent about $10 million on the fight against spartina. But many say the tide didn’t start to turn until 2004, when the EPA gave the go-ahead to use the herbicide imazapyr against aquatic weeds.

Effective herbicide

Before then, officials largely used the herbicide glyphosate, which WSU extensionist Kim Patten says would burn treated spartina plants only to allow them to regrow.

Stationed near the state’s worst spartina site, Willapa Bay, protected by an inlet north of the mouth of the Columbia River, Patten’s research helped imazapyr receive EPA approval.

Imazapyr kills vegetation by disrupting DNA synthesis and cell growth, according to an EPA data sheet on the chemical. It is of relatively low toxicity to humans and is not a carcinogen.

However, the EPA recommends great care in its application, since it does not distinguish between the plants it kills. It is labeled practically nontoxic for mammals and birds and practically nontoxic to slightly toxic to fish.

“Before (imazapyr), you maybe get 10 to 20 percent control a year, but your growth is at 40 percent a year,” Patten said. “So you’re losing ground.”

Environmental concerns

Not everyone is convinced imazapyr is a good thing. Though Keeley O’Connell of the environmental group People for Puget Sound recognizes the herbicide has helped drastically reduce spartina acreage, she says there hasn’t been enough long-term research to prove it won’t harm the environment in the future.

“It’s not really that were against it; we’re being cautious,” said O’Connell, the group’s habitat restoration coordinator. “We’re not arguing the fact that it does seem to be doing a good job. … But there are still unknown long-term effects.”

O’Connell points to the pesticide DDT, which received government approval and was used widely for decades to kill malaria-carrying mosquitoes until it was banned in the U.S. in 1972 because of the adverse effects it was later found to have on the environment and human health. DDT can still be found in the tissue of orca whales, O’Connell said

But Phillips says that’s an unfair comparison. The government has many more stringent requirements for a chemical’s commercial sale than it did during the time of DDT. And Phillips said the goal is not to continue using imazapyr indefinitely, but to use it until spartina is effectively eradicated and then stop chemical applications.

Still, the Swinomish Tribal community refuses to use the chemical near its traditional shellfish beds for fear it will harm their clams and livelihood. Instead, the Swinomish manually dig up spartina with volunteer pulling parties or limit its growth by placing landscape fabric along its shellfish mud flats.

Such efforts are more time-intensive and aren’t always as effective as herbicide, but Eric Dennis of the tribe’s public works department thinks it’s the right thing to do.

“Imazapyr just hasn’t been around long enough, and it always seems that something comes along later down the road,” said Dennis.

One of Skagit County’s worst spartina spots is Turners Cove on the northwest corner of the Swinomish Reservation, where the tribe does not use the chemical.

Rogers still says imazapyr is the main reason he is close to nipping Skagit’s spartina in the bud. And though crews will have to keep monitoring shores for spartina upcroppings for years to come, Patten estimates the invasive grass can be gone for good from the state in eight years.

“Our end game is eradication, and we will be successful,” Patten said.

If collaboration continues between the state and local governments and private groups and the state Legislature continues its current spartina appropriations of $880,000 annually, Phillips also thinks spartina can be eliminated.

“It will definitely be difficult, but it’s an attainable goal,” Phillips said. “There’s never been a success on this scale.”