A monster weed is invading the Iowa Great Lakes and no one is sure how to stop it

By Donnelle Eller , deller@dmreg.com
Des Moines Register

ORLEANS, Ia. — A couple weeks ago, Orleans Mayor Bill Maas looked out over an upper East Okoboji Lake that resembled an unkempt golf course, covered in an expanse of brown turf.

Invasive curlyleaf pondweed has been choking East Okoboji Lake, snarling boat propellers, burning up motors and shutting down swimming, tubing and other water sports in an area that depends on recreation.

The seasonal plant that dies out by summer is causing problems in other lakes — Upper and Lower Gar, and Minnewashta — and it’s inching into West Okoboji and Spirit Lake, threatening the area’s tourism industry that feeds the area economy, area residents say.

“It makes you sick. It’s a pretty lake that has become an eyesore,” said Ron Grothe, who is fighting the county’s attempt to push up his property valuation by about $21,000 on his home in upper East Okoboji Lake.

“There’s no way property values have increased. … You’ve lost any recreational use.”

The weed’s invasion is driving heated debates about how to control it — from using costly mechanical removal to administering herbicides that raise concerns about drinking water safety.

“Our customers don’t want chemicals being added directly to the water,” said Eric Stoll, general manager of Mildford Municipal Utilities, which provides drinking water to about 5,000 customers in Milford, West Okoboji and other towns.

“We’re open to listening to possible solutions, but we just don’t want a knee-jerk reaction that impacts the entire watershed.”

The Iowa Department of Natural Resources killed East Okoboji’s plan last year to use chemicals to battle the cold-water weed, telling area lake associations and residents they must reach consensus on a plan before they can move forward.

It could be difficult. Anger has grown as the plant has overrun upper East Okoboji and other lakes.

“The community is at a boiling point, and it’s going to end up in your lap,” Bill Van Orsdel, president of the Iowa Great Lakes Association, told DNR Director Chuck Gipp, who met with concerned residents recently.

‘Pondweed is everywhere’

Mark Petersen’s massive aquatic weed harvester is whining after logging 300 hours this spring, chopping and pulling out about 450,000 pounds of weeds from East Okoboji Lake.

“Curlyleaf pondweed is everywhere,” Petersen said. But “the worst of the worst” is upper East Okoboji.

His company, Underwater Solutions, has cut paths through East Okoboji, so boats, especially those needed for emergencies, can move through the matted plants.

The 10,000-pound barge, powered by paddle wheels, is fitted with an auger that chews through sinewy weeds before moving them up onto a conveyor belt. Eventually, the plants roll onto another barge and are hauled to shore.

At one point, Petersen said he had to hire dump trucks to carry mountains of weeds away. He’s drying the plants in a couple of remote spots, hoping farmers might be able to use them for fertilizer.

Mechanical weed removal can be expensive. This year, it cost about $21,000 to cut weeds from about 20 acres, just a slice of about 600 acres carpeting upper East Okoboji.

“It’s like trying to mow an 18-hole golf course with a push mower,” said Maas, who is also president of the East Okoboji Lakes Improvement Corp.

The group snagged a $16,000 DNR grant that local residents matched with $5,000.

The plants will naturally die by month’s end, although it will bring new problems: Large balls of dead weeds could push into docks and harbors that crews such as Petersen’s must remove.

The plants left in the water will decompose, potentially fostering blue-green algae blooms and fish kills.

A ‘lot more’ fish

Though the plant is invasive, it brings some benefits, said Mike Hawkins, a fisheries biologist for the Iowa Department of Natural Resources.

It helps clean the water, using nutrients that algae want. And fish love the food and habitat the plants provide.

The anglers have followed, looking for bass, musky, walleyes, northern pike and perch, said Maas and others.

“We had all those fish before. Now, there’s just a lot more of them,” said Lisa Vander Woude, who owns Pioneer Beach Resource & Woude’s Bay Bar with her husband, Rick.

The anglers have helped replace lost business from the lake. Sometimes boaters trying to reach the neighborhood watering hole stall out — or fear to navigate the lake, especially at night when it’s trickier to stay in the cleared path.

“It’s as bad as I’ve ever seen it,” Vander Woude said.

Shallow lakes endangered

Hawkins, the DNR biologist, said curlyleaf pondweed is exploding because the area has experienced consecutive mild winters that began in 2011, the start of a drought that carried into 2012.

Reduced amounts of winter ice across the lakes, combined with light snow cover, enable sunlight to reach deeper into the water.

Cleaner water in East Okoboji, as well as the rest of the chain, also helps the weed to prosper, Hawkins said. Sunshine can more easily reach “nutrient-rich sediment” in shallower lakes, with each spring bloom providing more seeds for the next.

The weed also is creeping into the harbors and shorelines of Big Spirit and West Okoboji lakes, typically filled all summer with vacationers. But it’s unlikely the plant could overtake the lakes, given their depth and sandy and gravel bottoms, Hawkins said.

Last year, East Okoboji Lake groups wanted to use endothall, the active ingredient in products such as Aquathol K, to create a 100-foot-wide boating lane around the upper lake’s shoreline.

The herbicide can’t be used within 600 feet of drinking water intakes; herbicide supporters note that Upper East Okoboji Lake is nearly 6 miles away from Milford’s water source.

They also planned to use mechanical cutting.

Stoll, general manager of the Milford Municipal Utilities, said he and the utility’s customers need more information that demonstrates the herbicide is safe to use. Other cities use Big Spirit and West Okoboji lakes as well for drinking water.

“We’re worried about chemical use escalating,” he said. “The idea of having a swimming pool — or a sterile environment to boat in — is a stretch for me to understand.”

Hoping to force action

Grothe said he and his wife, Rayna, hope their property tax protest — potentially cutting local tax revenue if others follow suit — will send a message to leaders that something needs to be done to control curlyleaf pondweed.

Rayna Grothe is taking the couple’s protest to the state review board after local officials denied it.

“We’re lake rats. We’re on the lake a lot,” she said, adding that they’ve lost about half of the lakes’ prime recreation season. “It breaks my heart.”

“We’d rather pay more taxes than watch the lake deteriorate,” said Rayna Grothe, who lives with her husband in Rochester, Minn.

Grothe and Aaron Jones, who owns Re/Max Lakes Realty, said families will look to other lakes to spend their weekends, vacations and retirements if the weeds remain.

Homes on East Okoboji can cost up to $1.5 million, Jones said. Even a modest home runs $300,000 to $400,000.

“I promise you they’re going to think three times, four times, five times harder before buying that property,” Jones said.

Despite assurances, Jones is worried that curlyleaf pondweed will invade other lakes, threatening the Okoboji’s economic lifeline of tourism.

“This weed will have the ability to wipe out the local tourism economy and sink property values if nothing is done,” he said.

The trouble with clear water

Iowa is working hard, investing about $8.2 million annually on average, to make recreational lakes cleaner.

But with cleaner lakes comes aquatic plants — typically native species — and they, too, cause waves.

For example, Black Hawk Lake near Lake View in western Iowa underwent a significant lake renovation effort with the 2012 drought, killing all the fish and starting over.

Within one year, water clarity went from an average of 6 inches to 6 feet deep, said Ben Wallace, the DNR fisheries biologist based in Lake View.

With sunlight reaching deep into the water, “75 percent of the lake was topped out with vegetation,” said Ben Wallace, the DNR fisheries biologist based in Lake View. “We hadn’t seen vegetation in decades. It happened all at once.”

Local residents were upset.

“I got a lot of phone calls, with comments like: ‘I’ve never seen the water as clear as it is now. But I’d like to have the lake the way it was, because at least I could use my boat,'” said Wallace, adding that the lake used to look like “pea soup.”

In response, the community decided to use a herbicide, mechanical removal (the state paid to have a machine at the lake full-time that the city operates) as well as hand-pulling near docks.
They’re also working upstream to cut sediment and phosphorus and nitrogen losses.

Today, some areas with undeveloped shorelines are thick with vegetation, Wallace said. But residents control plants elsewhere in the lake, which is not used for drinking water.

The plants “suck up the nitrogen and phosphorus … directly competing with algae,” he said. Toxic blue-green algae can be dangerous for children, pets and livestock.

“It’s not all roses. We have our struggles. We still have blue-green algae blooms, but we’re trending in the right direction,” Wallace said. “We’ve shortened the window.”

Taking matters into their own hands

Petersen, who owns Underwater Solutions, sees some residents illegally pouring chemicals that might not be safe to use into the water around their docks, trying to handle the problem themselves.

“Everybody thinks ‘my little bit won’t hurt anything,'” he said.

That’s the problem, said Maas, the Orleans mayor: Without a broader community approach, individuals take action that’s more harmful to people, animals and plants.

Hawkins recommends removing about 15 percent of the curlyleaf pondweed with herbicide and mechanical removal.

And, he said, the region needs to keep working to cut runoff from urban development and farms, such as restoring wetlands that help filter pollutants.

The annual costs to remove the weeds range from $30,000 using only herbicides to about $80,000 for mechanical harvesting only.

Maas said the community remains fragmented over its approach.

“You go to Hy-Vee and you hear 47 different solutions each morning,” he said.

John Wills, a state representative and vice president of the Okoboji Protective Association, urged residents meeting with Gipp to “not overreact.”

“Let’s use a balanced approach. Let’s not nuke the northeast end of Lake Okoboji,” Wills said in the Gipp meeting. “It might actually hurt.”