CARP ARE KILLING Howard and Mud Lakes. These two Anoka County lakes are scheduled to be rescued this month; they'll be given a poison pill that will kill not only the carp, but every fish in the lakes. The Department of Natural Resources will inject a poison called Rotenone into most of Howard Lake. The same poison will be sprayed over the remainder of Howard and all of the very shallow Mud Lake. The lake will be restocked with northern pike next spring--in theory, quickly returning the ecosystem to normal.
Bottom feeders, carp scour lake floors, sucking in dirt and sifting it to find food. In the process, they uproot plants and blow out clouds of muddy water, blocking sunlight and keeping new plants from growing. Without the plants to feed other animals, much of the food chain collapses. The problem is man-made; carp were imported to the United States from Europe in the 1920s to be used as game fish.
Nobody's arguing that carp are pests, but the DNR plan scares some lake-area residents. They believe the DNR's effort to undo an ecological disaster will cause other, more serious problems, possibly with their own health. They've formed a group called Citizens Against Rotenone Poisoning, or CARP, to battle the plan.
CARP members say that in addition to Rotenone, the fish-killing spray contains cancer-causing chemicals listed on the label as inert ingredients. "In a previous spraying up in Knife Lake there was an independent analysis of the preparation that found a lot of hazardous chemicals in it, like benzene, zylene, toluene, cumene and various highly toxic materials," says Dr. Charles Huver, retired University of Minnesota biology professor. "Toluene and zylene are suspected carcinogens and benzene is a confirmed carcinogen."
Bob Welsh, the DNR's North Metro Area wildlife manager, says there's no threat. "These inert ingredients are registered and deemed safe by our federal Environmental Protection Agency when used as the label indicates, which we are certainly doing," he says. But leaving those inert ingredients aside, the warnings on the poison's label are enough to scare anyone: "Fatal if inhaled. May be fatal if swallowed. Harmful if absorbed through skin. Do not breathe spray mist." The DNR says those warnings are for undiluted Rotenone. Mixed into the lake, there should be only 200 rotenone molecules for every billion water molecules, says Welsh. "A 132-pound person would have to drink 16,000 gallons of raw lake water to consume a lethal dose of Rotenone. That's simply not possible. You'd die from water before you'd ever die from this chemical."
Nonetheless, the thought of helicopters spraying chemicals overhead is unsettling to CARP members. "There's going to be drift over the surrounding area," says Huver. "It's a real danger to the people who live around the edge of the lake. There are a lot of families with children and there's a daycare center just across the street from the lake."
The DNR doesn't dismiss the risk of overspray, but says precautions will be taken, like spraying only when winds are less than 5 miles per hour. "We have nozzles that ensure large droplets, rather than a mist-type or fog-type of application," says Welsh. "The pilot is registered and trained to apply this type of material and is instructed to fly no more than 20 feet off the surface off the water or where they're applying the chemical."
Huver says rather than poison the lake, officials should look at the fish as a potential economic boon. "They should invite commercial fisherman to net the carp, and to build a fishing pier so that anglers could catch them," he says. "We have an increasing Asian population in the Twin Cities and many of them would certainly make use of this resource. The Asians value carp very highly." The DNR counters that netting has failed on other lakes.
CARP also claims that Rice Creek eventually flows into Centerville Lake and becomes part of St. Paul's water supply. According to the St. Paul Water Department, that's usually not true. "That water supply is used primarily as a backup for us, we haven't drawn any water out of that lake for the last four or five years," says David Wagner, assistant production supervisor for St. Paul's water department.
This last argument may actually be CARP's best hope of stopping the DNR. Members are asking Ramsey County for a risk assessment. If there's a risk, CARP can fight the plan in court. But those efforts will be in vain unless they happen quickly: The poisoning of Mud and Howard Lakes is scheduled to begin October 21.
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