Frequently asked Questions
Q: What is the cause of Swimmers Itch?
A: Several species of parasites known as blood flukes (all in the genus Schistosoma) are known to cause swimmers' itch. The adult parasites live in the bloodstream of a host animal, which may be a bird, fish, turtle or muskrat. The adults produce eggs which are released from the host and are subsequently ingested by snails. A free-swimming larva later emerges from the intermediate-host snail looking for a suitable host animal. If it encounters one, it burrows through the animal's skin and enters its bloodstream, completing the life cycle. If the larva encounters a human, however, it attempts to invade but is unable to get further than penetration of the skin. The human immune response rapidly kills the fluke, which releases an allergenic substance that causes the characteristic rash.
Q: What as a Waseca resident can I do to improve Waseca Lakes?
A: Some issues are larger scale, however, and need to be addressed at a community level. We all need to be aware of the way that land use in the watershed affects our lakes. A lake is a mirror image of its watershed. Each time water movement to the lakes is changed as a result of urbanization, agriculture, industrial or residential development, wetland drainage, or influx of non-watershed water, there is a potential water-quality impact. These issues might seem overwhelming but many of the watershed impacts from a quantitative perspective are known and understood. We need to seriously consider creating a counter for every impact we generate in the lakes' watersheds so that no net environmental damage occurs. For example, when a new development is being planned we should consider requiring the establishment of storm detention basins to handle runoff from all of the impervious surfaces in the development. "No net gain" of runoff quantity or rapidity should be seriously considered. We need to fully incorporate water quality protection into our manner of doing business so that our natural surroundings are protected for the use and enjoyment of future generations. Second, we need to become a unified body of informed citizens. A well-organized and informed group that understands the issues will have much greater success than one driven only by emotion and hearsay. There are many different issues to address concerning the improvement of the lakes and some of these issues are expensive and politically contentious. Taking this into account only heightens the need to present a strong well-informed case for any changes being proposed. Currently, the Waseca Lakes Association is starting to form that unified body but good broad representation from within the community is necessary to achieve the best possible outcome.
Q: What Causes a Lake to Winter Kill such as Loon Lake in 1999/2000?
A: By November most lakes in our area are thoroughly mixed from the strong winds that occur in the fall resulting in oxygen being naturally added to the water when the wind and water interface. During December ice and snow form on the lakes sealing the water from the atmosphere thus eliminating oxygen input from outside sources. Aquatic plants such as algae and rooted submergent plants can help produce oxygen during the winter as long as light can penetrate down through the snow and ice. But winters like this one that starts early and has large amounts of snow create conditions that completely eliminate any light penetration to the plants and thus they start to decay. The decompositions of the plants and other organic matter (i.e., leaves, plants, waste from industry, humans, waterfowl or fish) that accumulate on the lake bottom consume oxygen during this period and can create a large enough deficit that a lake can lose all of the oxygen in the water volume causing fish and other aquatic organisms to die. Preventing Winters kill: Winter kills are not something that can be predicted but we can certainly lessen their frequency through the use of winter aeration systems. Aeration systems are most suitable on shallow lakes with histories of frequent winter kill events such a Loon Lake and Lake Elysian. Shallow lakes often lack enough water volume to maintain good oxygen concentrations throughout the winter. There are many different varieties of aeration systems and they all have their benefits and drawl backs. The most commonly used system in this area is called a bubbler system. These systems are designed to run a high volume of air at a very low pressure through air line connected to aeration heads place on the lake bottom (i.e., Loon lake). Bubbler aeration systems function by opening up water so that oxygen exchange occurs naturally from aquatic plants and through the wind and water mixing at the surface. These systems also help distribute oxygen by mixing the entire volume of water in the lake. This allows oxygen concentrations to maintain a higher average concentration over the entire volume of the lake restricting or eliminating the oxygen-depleted zone of water near the bottom. An aeration system will not completely rule out the possibility of a winter kill. In fact, this winter has tested many of the aeration systems in the area and presently most shallow lakes and ponds without an aeration system have very low oxygen concentrations or possibly have experienced some degree of winter kill.
Q: What is the main cause of the mid-summer algae blooms in the lake?
A: Most of the lakes in southern Minnesota are naturally fertile due to the productive soils of their watersheds. The realization of this natural fertility has been substantially increased as a result of human activities in most watersheds, however. Lake fertility may best be described in terms of nutrients, primarily phosphorus and nitrogen, which enter the water. In many ways, phosphorus is a limiting nutrient in our waters and a small amount of phosphorus can generate a large result. Phosphorus comes from many sources including fertilizers, industrial products, and soils. Currently, phosphorus levels in Clear lake are at a record high for the lake and are higher than levels in most area lakes. Midsummer algae blooms on Clear lake are a result of several factors: one is the presence of curled pondweed, an exotic plant that originated in Asia. Another is the decline of natural vegetation in the lake. Curled pondweed has been in Minnesota for more than a century and is widely distributed. It has some unique attributes which allow the plant to dominate a lake's plant community for periods of time. Curled pondweed starts growing under the ice in December, depending upon light penetration. After ice-out, the plant grows rapidly. It suppresses algae and thus the water is usually clear during May and June. By July the plants die back, releasing nutrients into the water which algae quickly utilize, typically resulting in an algae bloom shortly after the pondweed disappears. The poor stands of native emergent and submergent vegetation on Clear lake coupled with the high levels of phosphorus allow the pondweed to flourish. Currently, the volume of water entering Clear lake far exceeds the level needed to maintain the lake level at a run-out elevation. Annual fluctuation in water levels of several feet is necessary to reestablish many types of natural emergent vegetation. The current water budget for Clear lake will not allow for such changes, which prior to dams and watershed development would occur as natural conditions dictated. Last summer Clear Lake maintained a higher water level than many lakes having a much larger watershed. This phenomenon suggests the lake remained high due to groundwater support or from other sources in the watershed. Without these fluctuations the likelihood of reestablishing native vegetation is low.