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Frequently Asked Questions

Have a question? Take a moment to browse through these frequently asked questions for quick answers. Don’t see your question or need more information? Please feel free to email info@greenlakeassociation.com or call our office at 920.294.6480.

What Causes Algae?

Algal blooms are an unusually dense growth of aquatic single celled plants (algae). Excessive amounts of nutrients that enter our lakes leads to eutrophication (accelerated plant growth). Sometimes plant growth may be in the form of nuisance algae that “bloom,” turning the water pea green and sometimes even causing fish kills. They occur, frequently to the point where they discolor the water, when ideal factors combine to promote growth—generally light, temperature, salinity and nutrients. Algal blooms are a natural phenomenon but their frequency, duration, extent and density are all increased in waters where human activities on land increase nutrient runoff.

Name That Algae

If your algae look like fluffy clouds or cotton candy, there’s a good chance it’s probably filamentous algae, sometimes called “moss” or “pond scum.” Cladophora feels “cottony,” while spirogyra is bright green and very slimy to the touch, and pithophora (or “horse hair”) has a very coarse texture like horse hair or steel wool. As algae grows, it produces oxygen that gets trapped in the entangled strands of algae. This entrapped oxygen makes the algae buoyant and causes it to rise to the surface.

Is Algae Bad?

Algae are necessary for a healthy lake ecosystem, but there can be too much algae. When this happens, the grazers who eat the algae can’t keep up. As the uneaten algae die off, they sink to the lake bottom and decay. The process of decay requires bacteria, which in turn require oxygen. If there is an abundance of dead algae, bacteria use up too much oxygen, and there isn’t enough left over for all of the animals, like insects and fish. Too much algae can also give lakes an unpleasant green color or a surface scum.

Unlike toxic blue-green algae which is blue-green in color (but can be brown or purple) and appears cloudy or like thick pea soup, Cladophora, pithophora and spirogyra are from the green algae family. Green algae don’t produce toxins but it is still important to think about practicing good hygiene, such as washing off, if you come in contact with it.

Can I get rid of it?

Short term, the best method for homeowners to remove filamentous algae is to rake out the floating clumps and compost these piles or use them in your garden as mulch. Chemical control requires a permit from WDNR. Long term, lake property owners and farmers can limit the amount of water and nutrients reaching the lake. Reducing fertilizer use, maintaining septic systems, keeping animal waste out of water ways and storm drains, preventing soil erosion on farms and construction sites, planting buffers along waterways, and keeping leaves and grass clippings out of the streets are just a few of the ways that we can all reduce phosphorus runoff over the long run to help keep the problem from getting worse.

Why Does the Amount of Vegetation in the Lake Vary From Year to Year?

In recent summers, many Wisconsin lakes have experienced and increase in aquatic vegetation growth. While there isn’t quick or easy answers, water resource professionals theorize that increases in aquatic vegetation are the result of a variety of occurrences:

  • Early and very warm springs boost the development of new plants.
  • Record breaking temperatures in the spring and summer with above average growing degree days.
  • More frequent and intense rain events increase nutrient loads to Green Lake and contribute to increased vegetation growth. Periods of calm winds, hot weather and an ample supply of nutrients throughout the summer can fuel the growth of algae and duckweed.
  • Zebra mussels in large numbers have the ability to make the water clearer because an adult zebra mussel can filter a liter of water per day, siphoning out all the small particles they encounter. Increased water clarity allows for more light penetration which aids the growth of aquatic plants.

In sum, clear water, nutrients, periods of calm weather, low currents, warm water and other factors all can affect vegetation growth in Green Lake.

How Are Fish Stocked In Green Lake

Every year 20,000 – 25,000 fish ranging from seven to eight months old travel from various fish rearing facilities throughout Wisconsin and arrive at the Green Lake Fish Rearing Facility. This number is determined by the Wisconsin Department of Natural Resources (WDNR) and is based upon what the WDNR thinks the lake and the fish rearing facility can support. In 2010, nearly 21,000 lake trout and 2,500 northern pike were stocked in Green Lake. Historically, brown trout have been a stocked fish species, but were not stocked in 2010 due to recent concerns of VHS, a deadly fish virus categorized as an aquatic invasive species.

Additional efforts have been made to help improve Green Lake’s fishery by reducing Green Lake’s carp population. Certain indicators suggest that the carp population may be declining in Green Lake. Each year, the Green Lake Sanitary District works with commercial fishermen to harvest carp from Green Lake.

View Fish Stocking Data

Who Removes the Vegetation in Front of my Pier?

The Green Lake Sanitary District (GLSD) spends the summer months (June – August) making its way around Green Lake with an aquatic harvesting machine to remove excess vegetation. The GLSD makes about three trips around the lake during the summer, beginning at Silver Creek or the Mill Pond. The cutter operates at four miles an hour and only cuts five feet below the water surface. In addition, the cutter can only operate in areas that have more than two feet of water.

In accordance with a harvesting permit granted from the WDNR, the Green Lake Sanitary District (GLSD) is the primary organization that manages and sponsors AQWEED, an aquatic harvesting program that cuts and removes nuisance aquatic plants from Big Green Lake. The GLA and the City of Green Lake contribute funds each year to AQWEED in support of the program.

Does Rosendale Dairy Spread Manure in our Watershed?

Rosendale Dairy is a Holstein milking operation located in Fond du Lac County which consists of a complex of free stall barns, and a milking parlor, a feed storage area, and three liquid manure storage facilities. Also referred to as a CAFO (Concentrated Animal Feeding Operation) Rosendale Dairy, when fully populated, will house 8400 milking and dry cows and 450 steers.

As part of its approved nutrient management plan, Rosendale Dairy has contracted with area farmers, who need fertilizer to aid in plant growth, to spread 93,162,600 gallons of liquid manure per year on area cropland, some of which is in the Green Lake watershed.

Rosendale dairy uses a method of manure spreading called immediate incorporation on most of its manure spreading sites in order to reduce the runoff of nutrients such as phosphorus, nitrogen, and organic matter. Additionally, because some of the cropland near Big Green Lake contains Surface Water Quality Management Areas (SWQMA), the WDNR requires additional precautions which include:

Maintaining a 100-foot spreading setback from navigable waters OR Implementing practices equal to or better than the required 100-foot setback which includes an option used by Rosendale Dairy to maintain a 25-foot setback from surface water and immediate incorporation of manure in the field. CAFO’s, including Rosendale Dairy, are also:

  • Restricted from surface applying manure when precipitation is forecasted within 24 hours
  • Prohibited from saturated or shallow bedrock soils
  • Prohibited from spreading liquid manure on frozen or snow covered ground
  • Prohibited from spreading during February and March when runoff risk is highest.
  • Winter spreading of solid manure is allowable on low risk fields except for the February and March time period. Rosendale Dairy will not be spreading any manure during winter months.

The smell during spreading can be very strong depending on the direction of the wind and number of croplands using manure, but the WDNR stated that spreading typically occurs roughly once to twice per year.

Using manure from CAFO’s (Concentrated Animal Feeding Operations) to fertilize cropland is not without controversy. Proponents of using cow manure from CAFO’s argue that cow manure from a local CAFO is more natural and less carbon intensive than synthetic chemical fertilizers shipped across the country and/or internationally. Proponents also argue that prior to applying manure from CAFO’s, cropland is required to have approved nutrient management plans which clearly specify the amount, source, placement, form and timing of the fertilizer in order to protect the environment. Conversely, opponents of using cow manure from CAFO’s to fertilize cropland argue that the amount of nutrients, the quantity of manure used, and the odor from CAFO manure is much more intense and detrimental to the environment than manure from smaller farms or farms with pasture raised cows. Opponents are also concerned about the possibility of increased concentrations of hormones and antibiotic residues in CAFO cow manure. While nutrient management plans outline manure application processes with the goal to reduce non-point pollution, opponents also argue that nutrient management plans are not always implemented correctly and that there is a lack of enforcement to ensure compliance with the plans which can lead to possible surface water pollution and ground water contamination.

Do I (Or My Child) Need a License to Operate a Motorized Boat?

Anyone born after Jan. 1st 1989 is required to take a boaters safety course to legally operate a boat or personal watercraft (PWC) in the state of Wisconsin. Anyone is eligible to take a boater safety class and receive a safety education completion certificate. The certificate is not valid for a child until he or she is 12 years old.

Learn More

Do I Need to Register my Pier?

Lawmakers created a free, one-time registration process for piers first placed in the water before Feb. 6, 2004, to grandfather in most of the larger existing piers that exceeded the size standards.

Learn More Pier Registration

Marsh, Estuary, Creek...What's the Difference?

Certain bodies of water can be difficult to define. Each person, depending on their location, use of the water, and personal background, may call it something different. Below we’ve provided definitions and corresponding photos to better assist in understanding our area waters. Creeks are natural streams of water normally smaller than, and often a tributary to, a river. Marshes can be categorized as deep water marshes or shallow water marshes. A deep water marsh is anywhere from 6 in. to 3 ft. deep and dominated by submergent, floating leaf, and emergent plants.

Alternatively, shallow water marshes are up to 6 in. deep and have standing water throughout the growing season. It is usually dominated by cattails, bulrush, arrowhead, and lake sedges.

What Should I Look for When Purchasing Lake Property?

There are many things to consider before investing in waterfront property. The Wisconsin Department of Natural Resources and the University of Wisconsin-Extension published a great resource that includes what to consider before beginning your search, how to determine the right lake or river, and factors for choosing perfect property.

View Choosing the Right Waterfront Property

Who Determines the Level of the Lake?

The WDNR has the power and responsibility under section 31.02 of the Wisconsin Statutes to regulate and control the level and flow of water in all navigable waters. Green Lake water levels are adjusted by the Mill-pond Dam, which the City of Green Lake operates.

The dam consists of an earthen embankment with concrete abutments forming three open spaces or ‘gates’. Removable 6′ x 6″ timbers stacked vertically within the gate are spaced to create a wall against the flow of water. By removing or replacing these boards, the water level is decreased or increased correspondingly to the extent that the lake’s water input will sustain the intended level. According to an order issued by the WDNR, the City of Green Lake is required to operate the dam so that:

  • The lake level shall not exceed elevation 796.49 (MSL) between the spring break up and September 30
  • Starting September 30, the level shall be lowered slowly to 795.74 by October 31 and maintained at that level until spring break up in order to prevent harmful ice pile up and erosion around the shore when spring break up occurs.

The City measures the water levels by taking readings from a staff gauge with graduations in feet and tenths, which is mounted on a concrete abutment of the dam. Staff gauge readings corresponding to the WDNR specifications are:

Elevation/Staff Gauge

Summer High: 796.49 /6.5

Winter Low: 795.74 /5.7

The Millpond park is open to the public and the staff gauge is accessible to anyone interested in checking the water level. The City takes readings nearly every day during the summer and keeps a record of the readings, which is also available for public viewing.

Where Can I Dispose of my Toxic or Hazardous Waste?

The Green Lake County Land Conservation Department offers Clean Sweep, a program that allows residents to dispose of their hazardous waste.

Learn More about Clean Sweep