Keeping lake's health in mind

Matt Whetstone | Cadillac News DEQ pollution prevention and compliance assistance representative Pat Donovan motors his way across Lake Cadillac on his way to the weed beds identified as Eurasian water milfoil.

CADILLAC - Pat Donovan maneuvered his fishing boat quickly from the launch in Lake Mitchell's little cove to the canal and Lake Cadillac.

On that hot, humid Friday morning, the conversation between Donovan, a Department of Environmental Quality agent, and Dave Foley, a retired educator and member of Lake Mitchell Improvement Board, covered all things aquatic - fish, weeds, sun, nutrients, fishing, water quality, fish and some more weeds.

As the two approached several large weed beds near the old naval reserve, talk shifted to the latter. Specifically, the two, along with a Cadillac News reporter, were there to witness firsthand the abundant growth of Eurasian water milfoil, an invasive plant species that will eventually choke out native vegetation if left unchecked.

Eurasian milfoil and nutrients

This invasive aquatic plant likely came to Lake Mitchell in the form of a tiny fragment left on a boat or propeller. The Lake Mitchell Improvement Board spends about $60,000 annually keeping the weed under control with a combination strategy of selective herbicide use and targeted harvesting.

This year, the board's engineering firm, Progressive AE, treated a total of 102 acres of lake bottom.

Until just this year, the problem in Lake Cadillac was not so visible. Milfoil tops emerged from the surface of the lake in the aforementioned area and there are a number of other areas in the lake where it is rising to the surface. When the last weed study was conducted in 2003, the outlook was good.

"The irony is in 2003, the lake was given basically a clean bill of health," said Cadillac City Manager Pete Stalker. "To have it explode like this, we're curious to what factors are driving this."

The city is well aware that nutrients in the water can fuel weed growth. Most often, fertilizer - more specifically phosphorus - is washed into the lake after a rainfall. Overfertilizing leaves excess nutrients on the lawn eagerly waiting for a plant to feed.

When fertilizing around the lake, Stalker said the city uses best practices, choosing phosphorus-free fertilizer, keeping track of nutrient levels through soil sampling and maintaining an untreated buffer around the lake.

Efrain Rosalez, who performed a non-point source pollution control study on the Upper Clam River Watershed in 1994, said one pound of phosphorus can fuel 500 pounds of plant growth. Samples taken at various locations around the two lakes in 1994 revealed very concentrated levels of phosphorus, some as high as 284 pounds per acre.

Eurasian milfoil eagerly feeds on the excess fertilizer and out-competes native plants.

As it grows to the lake surface, it steals sunlight from native vegetation. Milfoil also spreads rapidly, a sliver of the plant can root elsewhere and spread. If left alone, it could create nightmarish conditions for recreation.

Health of the fishery

"Eurasian milfoil makes it very difficult to fish," said Tom Rozich, a fisheries biologist with the Department of Natural Resources. "That's a big thing as far as anglers are concerned."

A healthy lake, Rozich said, has 40 to 50 percent of its shallow area covered in aquatic vegetation. This gives smaller fish a place to hide while leaving plenty of open areas for predator fish to hunt.

"We do not want to get to the point where Houghton Lake got to and do a whole lake treatment," Rozich said. "It would turn the lake into a fish bowl."

The key is treating the hotspots and learning to deal with the fact that Eurasian milfoil will not be eradicated completely, he said.

Launching control efforts

In his position at the DEQ, Pat Donovan seeks cooperation, not regulation. Unlike many of his colleagues in the department, Donovan focuses his efforts on education, discussion and voluntary stewardship.

Donovan's hope is people will understand the necessity to take action now and avail himself to provide information to control efforts. Already, there are a number of organizations that voluntary use best practices to lawn and turf fertilization. Donovan said getting involved and understanding that what goes into the ground or the storm sewer ends up affecting water quality.

"At the end of the day we need the citizens to step forward and say we need to do this to take care of the lakes," Donovan said. "The weeds are just a symptom of the overall health of the lake. If you don't go to the source of the problem, you only treat the symptom."

The Cadillac Area Visitors Bureau and the city of Cadillac are now putting together a group of interested parties.

"Things are in motion," Stalker said. "We have to figure out the treatment, we have to develop a structure or body to make decisions and develop a funding mechanism."

Some discussion so far has covered the possibility of developing a lake association. With the Lake Mitchell Board already in place, Stalker said there is potential for coordination between the two. At this point, Stalker said it would be wise for the community to "really start to think about the long-term health of the lake."

Meanwhile, the city is continuing to look at ways to develop an education campaign, study stormwater retention activities south of the lake, learn more about improvement boards and think about treatment options and timing.

Progressive AE, which also has conducted work on Lake Cadillac and Lake Missaukee in Lake City, visited Wednesday to perform another analysis of the weed growth.

In the 1994 pollution report, Rosalez gave a number of recommendations that would improve the health of the watershed and both lakes in the future. One recommendation is an educational campaign to get people thinking about smarter use of fertilizer as a starting point. Also, Rosalez said native vegetation could be planted along lake-shoreline to intercept some of the nutrients and control erosion.

"Millions of people have been touched by the lakes here - literally," Rosalez said. "The foundation is out there, we just need to build on it."

Anyone who would like to be active in process should contact Ted Newman at the Cadillac Area Visitors Bureau at 775-0657 or Pete Stalker at 775-0181.

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