Copper Sulfate is Deadly

The Higgins Lake Foundation does not endorse the practice of individuals adding chemicals to the lake for any reason, and research indicates that the application of copper sulfate in particular is not only toxic but also ineffective as a means of controlling Swimmers’ Itch.

The Higgins Lake Foundation is currently funding a study of Swimmers’ Itch in Higgins Lake conducted by scientists from MSU and had previously funded a study by Dr. Harvey Blankespoor, Professor Emeritus at Hope College. He has studied Swimmers’ Itch for 50 years and is now retired, but his website states:

For more than 50 years, the application of copper sulfate as a molluscicide was used on some of the larger recreational lakes to break the life cycle by killing the snail intermediate hosts. Although this method is still used, fewer lakes are requesting permits because of the uncertainty of long-term consequences to a particular lake and because the results are unpredictable.

Dr. Blankespoor’s son, Dr. Curtis Blankespoor, is a Professor of Biology at Calvin College and the University of Michigan Biological Station. He has studied Swimmers’ Itch for the past ten years and warns against the practice of using copper sulfate to kill snails which are the intermediate hosts in the life cycle of swimmer’s itch. While it’s true that copper sulfate kills snails, it also kills many other microorganisms in the ecosystem. And, as Dr. Blankespoor points out, “Since only about 2% of the snail population is infected with the Swimmers’ Itch parasite as opposed to 80-90% of the merganser duck population, it is not a particularly good use of resources nor an effective means of treatment for the parasite.”

According to Dr. Blankespoor, “There are two very large drawbacks in using copper sulfate to control Swimmers’ Itch. The first is a numbers thing. There are hundreds of thousands of snails in Higgins Lake, and with 1-2% carrying the parasite that causes Swimmers’ Itch, you are going to need literally tons of copper sulfate to kill enough snails to make a difference.

“And using that much copper sulfate leads to the second major drawback…the potential damage (short-term and long-term) to the entire Higgins Lake ecosystem. There would be a lot of ‘collateral damage’ to uninfected animals (snails and plants, and in turn the fish that indirectly rely on both these organisms). More importantly you would be introducing a massive amount of an inorganic metal that will stay in solution as long as the lake water doesn’t turn too acidic. All it would take would be for conditions to change slightly (e.g., the lake water to get more acidic) and all that added copper would precipitate out. If that happens, you would be looking at MAJOR changes in Higgins Lake.”

His opinion is reiterated by a publication from the Tip of the Mitt Watershed Council which states, “Despite the application of tens of thousands of pounds of copper sulfate in some lakes in the past 50 years, the occurrence and severity of Swimmers’ Itch has not noticeably diminished.”

Furthermore, a publication titled “Swimmers’ Itch in Michigan” published by the Michigan Department of Environmental Quality states that “there are indications the dying snails release large numbers of cercariae [the parasite that infects humans].”

According to Dr. Blankespoor, “People need to think in terms of management, not eradication. It is impossible at this point in time to eliminate Swimmers’ Itch. All we can do is try to reduce its effects.”

The Higgins Lake Foundation urges people to use preventative methods to avoid Swimmers’ Itch. Most people are able to prevent Swimmers’ Itch by applying a protective layer of lotion or baby oil to the skin before entering the water. There are also several brands of Swimmers’ Itch Guard which may be purchased locally or at the HLF office in Roscommon.

The focus of the Higgins Lake Foundation and its many projects has been to protect the health of the lake. The Foundation has committed vast resources to finding alternative treatments as opposed to putting chemicals in the lake.

We urge people to be good stewards of the lake and not look for an “easy fix’” which, as it turns out, is not a fix at all.