Chain of Lakes Drawdown - by Tom Sykora
A drawdown would have many benefits to local residents. The carp population would be reduced, allowing beneficial plants to flourish. These plants would in turn attract more ducks and waterfowl to the lakes to feed. Diamond would benefit from Hubbard, Schultz and Wheeler being able to remove more of the watershed nutrients. Instead of allowing nutrients such as phosphorus to pass through, they would act more as nutrient "sponges", if carp are removed and plants allowed to come back.
Local Hydrology, Fisheries, and Wildlife departments of the Minnesota DNR are currently working with the Lake Association to sort out the feasibility of cleaning up these three lakes to help the water quality of Diamond Lake.
Members of the Diamond Lake Association have begun meetings with local DNR staff regarding a temporary drawdown on the Hubbard, Schultz and Wheeler chain of lakes.
After doing water quality testing in our study, it was determined that over 70% of the phosphorus coming into Diamond Lake was entering through the carp trap from these three referenced lakes. Hubbard, Schultz and Wheeler are "eutrophic" or nutrient saturated, according to Blue Water Science, and incapable of absorbing nutrients during a watershed event such as a heavy rain. In other words, instead of acting as a natural soak or sink for chemicals, those lakes simply allow phosphorus to pass through to Diamond.
The Lake Association is considering a fish kill to promote beneficial weed growth. Beneficial weeds in these three lakes would utilize phosphorus and remove it from the water column. However, if there are excess carp in a body of water, plant life suffers. Carp eat plants, and will root out plant life, rendering a lake incapable of acting as a nutrient sink. Using chemicals is how some lake associations kill carp. A drawdown is much closer to a naturally occurring event during dry periods, o these three shallow lakes. (Carp are not native to the US, were brought here from Europe and have no natural predators to control their populations).
Since the majority of the nutrient load coming into Diamond Lake is from the Hubbard, Schultz, and Wheeler chain of lakes, the Lake Association is currently investigating the feasibility of draining down one or more of these lakes to do a fish kill this fall after duck season. Steve McComas of Blue Water Science has helped us with preliminary numbers, planning and identification of potential problems. Current the DNR is doing a hydrology study of the relative elevations of these three lakes, to better understand the mechanics of a potential drawdown. With the water levels being low this year, timing seems right for a carp/fish kill with the least possible expense.