Group Wants Phosphorous in Cedarville Bay Reduced
In an ongoing dispute about how to deal with the overgrown weeds in Cedarville Bay, and what may have caused their rapid growth, a local citizens group and biologists with the Department of Environmental Quality (DEQ) agree that water testing in the bay shows phosphate levels within acceptable state limits, but the citizens group wants to see levels reduced further.
The Les Cheneaux Waterways Restoration Committee, a subcommittee of the Les Cheneaux Watershed Council, claims the amount of phosphorus in the effluent from sewage treatment lagoons is still too high and it is fueling the rapid growth of the invasive weed, Eurasian watermilfoil. The group is calling for additional chemicals, like iron chloride, to further lower phosphorus levels, said Robert Smith, a member of the group who has been involved in testing water quality in the bay. Citizens also are asking that the channels and bay be dredged to promote more boat traffic and to increase circulation of the water there.
Randy Conroy, geologist for the Upper Peninsula District of the DEQ, said the agency would take action "if we thought that was some sort of detriment to public health."
But the DEQ has inspected the phosphate levels in the bay twice since April and says water quality there meets acceptable phosphorus levels under Michigan Water Quality Standards.
The bay is typically inspected two times every five years, and has been inspected twice in the last six months owing to a wastewater spill. The spill was properly cleaned up and the waterways meet quality standards, Mr. Conroy said.
Mr. Conroy told The St. Ignace News low water levels, warm temperatures, and nourishment from organic material carried into the bay by runoff are the most likely causes for the watermilfoil's rapid growth, not excessive phosphorus levels in wastewater discharges.
Eurasian watermilfoil is an invasive weed that successfully competes for space on the bottom of the waterways, crowding out native plants. It grows almost to the surface. The plants also add nutrients to the bay when they die and decay, which in turn, encourages more growth.
Near the surface, the weeds get caught in boat propellers and can cause motor seizures and occasional damage. Boaters avoid the weedclogged areas, and reduction in recreational boating hurts the Les Cheneaux economy.
To combat the growing weeds, this July the watershed council, Les Cheneaux Community Foundation, and Cedarville businessman Dan Carmichael collaborated to remove some of the weeds with a weed harvester purchased by Mr. Carmichael. The harvester cut the weeds at Cedarville Marine, which Mr. Carmichael owns, and boat slips for several of the local resorts.
"They trimmed all the slips in the marina and were very happy with it," Mr. Smith said.
But while mowing the weeds provides temporary relief for boaters, the plants grow back, and fragments clipped from the plants settle to the bottom and start new plants.
In 2007, Mr. Smith and the restoration committee also introduced weed-eating weevils into the water system to eat the watermilfoil. Mr. Smith said the weevils start at the growing tip of the weed and eat their way down to the root during the summer, then overwinter in the sediment along the shore.
Mr. Smith noted that the weevils don't get very far from shore, so the weeds further out in the bay are not affected by it.
"The weevils do a good job close to shore, but that's not where the boats are," he said.
Mr. Smith, who has a doctorate in microbiology from Central Michigan University, has been studying the Les Cheneaux waterway for seven years, supported by the Les Cheneaux Islands Association, Islands Wildlife, Community Foundation, and the Watershed Council.
He claims that while phosphorus levels are within state pollution guidelines, they are double what he says they should be. There is about four pounds of phosphates per 26 million gallons (0.019 milligrams per liter) of wastewater effluent in the discharge, he said.
"Even though we meet the state specs," he said, "our target is to get it down to two pounds."
The current phosphorus load is down considerably from 2.3 milligrams per liter, about 500 pounds per 26 million gallons, when the sewer expansion took place in 1990, Mr. Smith said. He noted that the weeds already existed in the waterways, but began to flourish after the expansion.
Grants awarded through the DEQ and Environmental Protection Agency can help clean up the waterways, Mr. Conroy said. They can fund impact studies, programs to deal with sedimentation issues, and help with establishing vegetation along the waterway to limit erosion and runoff of nutrients, like lawn fertilizers, into the water.
Clark Township Supervisor Linda Hudson said the township would like to enlist the DEQ to conduct an impact study of the bays and also make a recommendation for an alternative way to get rid of effluent from its wastewater treatment lagoons.
The restoration group contacted a consulting firm in May about the weed problem in the waterways. Mr. Smith said the firm, C2AE, wants $25,000 just to make an assessment on what action to take in the bay. The firm has offices in Gaylord, Grand Rapids, and Lansing.
"They're sitting there waiting for us to crank them up and set them loose," he said of the company.
But the Watershed Council does not have the funds available to have the assessment done, and Mr. Smith said it's the township's responsibility to arrange for such studies.
"That is the big question," Ms. Hudson said about which entity bears the responsibility of any course of action.
About 40 years ago, the U.S. Army Corps of Engineers dredged the navigation channels through the islands, in accordance with their mandate that the channels be maintained at seven feet deep and 100 feet wide. In the 1970s, however, local residents stopped the Corps' maintenance, fearing that the cloudy water from the operation would interfere with fish spawning. Subsequent dredging opportunities never materialized, and there now is no funding for such a project.
Mr. Smith is concerned about how any action taken will affect the future of the waterways, especially as population growth will increase the phosphate load in the bay.
"Ten years from now, the population is going to be different and we're probably going to be putting in more [phosphates]. We need to do some addressing of those issues now," he said.