water clarity – Aquarius-Systems

Lake Minnewawa Restoration Shows Long-Term Benefits of Harvesting

Fri, 22 Dec 2023 19:20:27 +0000

In the 1970’s Lake Minnewawa in Minnesota was so choked with weeds that residents could no longer enjoy the lake as they once had. The water clarity and the phosphorous levels were awful. People would pull their docks out of the water in July because boating was impossible.

Save Minnewawa Association was formed in 1977 and they purchased their first aquatic vegetation harvester in 1982. Since the harvester has been in use, not only have the amount of weeds decreased, but the water clarity has significantly increased.

A big reason for this is because there are fewer weeds dying in the lake and decomposing in the bottom of the lake. Also, the weeds contain a huge amount of phosphorous which is being removed along with the weeds. The more phosphorous in a lake, the more algae growth, therefore the lower the water clarity.

The board has heard the suggestion of controlling the weeds by using chemicals instead of the weed harvester. The cost of the chemicals is very prohibitive though. It was $250,000 dollars and the lake had to be treated twice a year for the first 5 years; a price tag of a half million dollars. Compared to approximately $25,000 a year it takes to run the weed harvester.

Aquatic Plants Play Key Role in Water Clarity Balance

Tue, 05 Dec 2023 22:23:44 +0000

Posted on July 9, 2013 by Dan O’Keefe, Michigan State University Extension

Aquatic ecologists tend to avoid the term “weeds” when referring to macrophytes – the rooted aquatic plants that many swimmers and boaters disdain. These plants provide food for waterfowl and habitat for fish, but they can also play a critical role in maintaining water clarity.

Many lakes and ponds have two stable states: weedy and clear or devoid of weeds and muddy. This leaves riparian landowners and lake managers with a choice between two undesirable endpoints when nutrient levels are intermediate.

At low nutrient levels, the rooted plants win out because water is clear and plenty of light reaches the bottom of the lake. At high nutrient levels, the algae win out and effectively shade out rooted plants – this means extremely low water clarity and sometimes harmful algal blooms. At intermediate nutrient levels, things get a bit tricky. In this case, lakes can be pushed in one direction or the other – sometimes inadvertently.

When rooted plants are destroyed, mucky bottoms get stirred up and re-suspend nutrients. Competition with algae ceases and foul blooms occur. If plant biomass is not mechanically removed, the rotting vegetation further adds to nutrient availability, turbidity, and algae growth.

Native Vegetative Shoreline Buffer

Mon, 04 Sep 2017 18:17:00 +0000

Probably the single most helpful thing we can all do to help keep surface waters clean is the addition of a native vegetative buffer along the lakeshore. Buffers help filter out and trap pollutants like fertilizers, herbicides and pet waste before they reach the water. In addition, the deep roots from native buffer plants help hold the soil at the shore in place so it does not erode into the lake.

The upper parts of native buffer plants have their importance, too, as they provide for the many animals who make their homes near the water. It is estimated that approximately 90 percent of all animals spend all or part of their life cycle at the lakeshore. Native shoreline buffers provide shelter from the elements, provide a place to build a nest, provide a place to gather food and a place to hide from predators.

Buffers can be as simple as leaving a strip of unmowed grass along the shore or they can be more involved by planting a number of different native plant varieties. Whether you just leave the grass grow or install a native plant buffer, your lake water clarity and quality will benefit. It is certainly a step in the right direction.

Read More https://dec.vermont.gov/sites/dec/files/wsm/lakes/Lakewise/docs/lp_VTlakescape.pdf