Current E. coli Counts
for Geneva Lake Beaches
Click on the Community to see their public beach results.
Boats docked, moored on Geneva Lake or stored as in-out service on
Geneva Lake WI by community.
dark blue = City of Lake Geneva
light blue = Linn north shore
green = Williams Bay
white = Fontana
Orange = Linn south shore.
Overview of the Big Foot Creek Watershed Study.
Big Foot Creek is locted on the southeast end of Geneva Lake. It drains a large wetland that inclules parts parts of Big Foot Beach State Park in its northern wetland. he creek has discharge degraded water quality for many years. Low oxygen, high phosphorus are two of the major water quality issues associated with the Creek. The GLEA has initiated a study to document the degraded water quality, identify the causes and recommend best management practices to improve Big Foot Creek's water quality.
The initial step (Phase I) in conducting the Watershed Study involves water sampling at several locations within the watershed. The purpose of the sampling is to confirm that the degraded water quality as previously identified. Water samples will be collected from several areas within the watershed during different seasons, and compared to a background groundwater sample. Results will be recorded in a spreadsheet format and presented in a final Phase I report. The goal is to abate the degraded water quality, specifically the high levels of phosphorus , low levels of oxygen and the reddish floc that is discharged to Geneva Lake.
Sample site – all samples will be grab samples preserved and processed according to accepted methods.
1 - Outlet to lake
2 - East of road at outlet
3 - North Branch
4 – South branch
5 – Groundwater discharge (background)
Parameters tested: Temperature*, pH*, conductivity* alkalinity*, dissolved oxygen*, turbidity*, iron, total phosphorus, suspended solids, ammonia, and Chemical Oxygen Demand (COD). Stream flow and discharge will be measured and calculated for each sampling at the lake outlet.
*Indicates parameters that will conducted in the filed or shortly after sampling by the sampling crew.
Mid to late spring (March-April of 2019)
Late summer – (August)
Late fall – (October)
Following a summer and fall storm event.
A Wisconsin DNR small scale lake planning grant was awarded in the amount of $3,000 to assist with the project’s costs. High school students from Badger High School assisted with sample collection and did some field/lab analysis (see above parameter tested*). The data is presently being processed and interpreted. A Phase I report will be prepared
A WI DNR lake grant is being applied for to conduct Phase II of the project. Phase II will involved refined sampling, if needed, site review and the preparation of recommended best management practices.
Five year Private Well Testing Program
Results of Groundwater testing in the Joint Geneva Lake Environmental Agency – Linn Sanitary District Long-Term Well Testing Program.
As a mean of understanding the groundwater quality within the Geneva Lake basin, the Geneva Lake Environmental Agency and the Linn Sanitary District entered into an agreement to monitor thirteen private drinking wells from different locations around the watershed. The importance of groundwater in the annual Geneva Lake water budget as identified in several studies makes it important to know what is in the groundwater and what it is delivering to Geneva Lake (Figure 1).
The original selection of wells to be involved in the sampling program was based upon several criteria.
Parameters tested for bacteria, nitrates,
Past testing results and participants (who wants to be involved?)
Location: density of homes and soils
Distribution within the watershed.
North and south shore,
Areas where our POWTS testing indicated a concentration of failing/old systems
Areas of high density of POWTS
Shallow groundwater, w/POWTS
Area where past well testing indicated bacterial contamination.
Nearby land use.
Land use and the use of private on-site wastewater treatment systems in the Town of Linn are potential threats to groundwater quality. It is important to know if and what impacts those potential threats have on the overall groundwater quality.
To get a good representation of the conditions around the lake, wells in different aquifers were chosen based upon location, past data and depth. Chosen wells were in both the north and south watershed areas of Geneva Lake. The groundwater shed boundary on the north side of Geneva Lake runs very close to the north shore of the lake. On the south side of the lake the groundwater shed runs up to three miles south of the lake on the southwest end of the lake and around a mile on the southeast end of the lake. A major portion of the Geneva Lake watershed extends southwest of the lake out into the Big Foot Prairie (Figure 2).
Depth of wells tested ranged from 84 ft. to 804 ft. Aquifers in the Geneva Lake area include the glacial outwash and till consisting of sand and gravel that range between 0 - 200 ft. and is found throughout the basin; Silurian dolomite, a limestone aquifer that exists as a thin layer just below the sand and gravel on the eastern end of the lake found at depths between 175 and 200 ft. and a Sandstone aquifer found below 200 ft. Between the limestone and the deep sandstone aquifer is the Maquoketa shale confining unit found only on the eastern half of the lake. Being a shale, this layer does not serve as an aquifer (Figure 3).
Wells 1, 3, 4, 5, 6, 10, 11, 12 and 13 are drawing from the sand and gravel aquifer. Well 7 is the deep sandstone aquifer. The depths of wells 2, 8, and 9 are unknown. A better idea of the aquifer that each well draws from can be obtain by reviewing the well drilling log. Not all well logs were found for the wells tested.
Of the 13 private wells tested in 2019 two had a positive total coliform and none had a positive E-coli (fecal coliform). None of the thirteen private wells tested exceeded the nitrate nitrogen drinking water standard. Only three had levels that were detectable, and they were both below the drinking water standard (Table 1).
Table 1. Private Well testing Results, Geneva Lake Watershed Walworth CO. WI 2018 and 2019
In addition to the private wells tested in this program thirteen public water supply systems were also looked at in terms of nitrogen and bacterial test results. Public water supply wells include municipal wells, restaurants, bars, hotels, schools, and subdivision wells. Public water supply systems are required to annually test their water for a wide range of parameters including nitrate nitrogen, total and fecal coliform bacteria.
The public water supply wells included in this report are located to the south, west and north of Geneva Lake. Not all depths were recorded, yet those recorded are of various depths ranging from 86 ft. at Kikkoman foods west of the lake, to 1500 ft. at South Shore Club located on the south shore of Geneva Lake.
The 2019 testing of these thirteen wells found bacteria to be absent and nitrate nitrogen to be below the drinking water standard (Table 2). It should be noted that the five highest nitrate values found in the thirteen public water supply wells were all located in the western portion of Geneva Lake’s groundwater shed.
Table 2. Public Well Testing Results, Walworth County.
Starry Stonewort Management on Geneva Lake
With the discovery of starry stonewort in Geneva Lake at several locations in the southeast corner of the lake outside the lagoon, starry stonewort’s best long-term management will shift from eradication to containment and control. Management will address population in the lagoon as well as any population found in the lake.
Long term management may include controlling this invasive through chemical treatment, hand pulling and possibly a few other options that are being tried on other lakes. As with a terrestrial environment, the best way to keep unwanted weeds from spreading in your lawn is to have a healthy lawn. It is the same with unwanted weeds in the lake. Keeping a healthy bio-diverse and balanced plant community will deter any unwanted weeds from establishing themselves and spreading throughout the lake.
Educational effort with boaters at the launch and the cleaning of boats before and after they enter the lake will help keep unwanted invasive species from getting into the lake and spreading. Keeping a clean boat while on the lake, such as removing vegetation and mud from anchors and props before you move to another site is one sure way of reducing the spread of an invasive within a lake. The GLEA is looking at ways to help establish cleaning stations at the different municipal launch sites. For information on the regulations for boat transfere and bait laws see
Future starry stonewort populations in Geneva Lake will also be managed to control and contain. Starry stonewort management will be a long-term commitment at any site where it has been identified in the lake.
A long term commitment to Clean-Boats Clean Waters ( https://dnr.wi.gov/lakes/cbcw/) practices at the launches will also be a must if we are to reduce the likelihood of new invasive species getting into Geneva Lake. Keeping a clean boats is the law!