Summary of the Lake Management Plan for Geneva Lake.
September 2008
By GLEA/twp

INTRODUCTION

Geneva Lake is a valuable resource for all of southeastern Wisconsin, especially for the communities located on its shore. Increases in population and development will continue to add pressure to develop and use Geneva Lake and its watershed.

The Lake Management Plan for Geneva Lake offers the water quality and resource protection needed to meet those demands and maintain Geneva Lake’s unique characteristics and quality. Over the years many efforts have been made by various local, state, and federal agencies to protect Geneva Lake. It is hoped that the Geneva Lake communities adopt this lake management plan to help guide them in future land and lake use decisions.

This Summary Information Sheet is a summary of a more comprehensive Lake Management Plan for Geneva Lake, released in July 2008. The complete management plan is the second edition of the Southeastern Wisconsin Regional Planning Commission’s (SEWRPC) Community Assistance Planning Report #60, first released in 1985. Most of the information in the new management plan is carried over from the first edition. Updated lake data came from a recent comprehensive Diagnostic Feasibility study that was done collectively by the United States Geological Survey, the Wisconsin Department of Natural Resources, the Geneva Lake Environmental Agency, the University of Wisconsin Extension, and the local communities.

The Management Plan identifies the Geneva Lake’s physical, chemical, biological and social resources. It establishes water quality and recreational use objectives along with recommendations for the most cost effective management practices. Some preliminary implementation cost and who is best suited to implement the recommendations are also presented in the complete management plan.

PHYSICAL CHARACTERISTICS:

The Geneva Lake is a deep glacial lake somewhat unique to southeastern Wisconsin (table1). Geneva Lake is located in south-central Walworth County, in southeastern Wisconsin. Located on its shores are the Villages of Fontana-on-Geneva Lake and Williams Bay, the City of Lake Geneva, and the Towns of Linn and Walworth. Within Geneva Lake’s watershed are lands within the Towns of Delavan, Geneva, and Bloomfield and the Village of Walworth. (figure1).

The atmosphere is the major source of water contributing 48% of the annual water input. Other sources and their annual contribution are; surface runoff 28%, stream flow 18% and groundwater 6%. Major water losses are the White River 60% and evaporation 40%.

LAKE FACTS
Table 1. Lake Facts
Surface Area 8.3 miles2 (5,262 ac)
Watershed Area 20.4 miles2 (13,045 ac)
Shape  
Maximum length
7.6 miles (Fontana to Lake Geneva)
Maximum width
2.1 miles (Williams Bay to South Shore)
Minimum width
0.5 miles (“The Narrows” Linn Township)
Shoreline Length 20.1 miles
Depth  
Maximum
141 ft
Average
57 ft
Less than 10 ft
11%
10 to 70 ft
45%
More than 70 ft
44%
Volume 320,945 acre-ft
Residence Time a 13.9 years
a Time required for a volume equivalent to the full volume of the lake to enter the lake from the lake’s water sources.

The Geneva Lake’s watershed is primarily glacial soils with glacial moraines forming the hills surrounding the lake basin. Geneva Lake is a long (7.6 miles) narrow lake that lies on a SW to NE axis. It has an irregular shoreline of 20.1 miles. It is the second deepest natural occurring lake in Wisconsin outside of the Great Lakes. Geneva Lake is a headwater lake which drains east into the White River through a controlled outlet structure of a dam and spillway. The White River further drains east to the Wisconsin/Illinois Fox River which flow south into the Illinois River.

Figure 1. Geneva Lake Communities.
Geneva Lake Communities

MANAGEMENT OBJECTIVES

Water Use and Water Quality Standards have been established for Geneva Lake and are the basis for Geneva Lake’s management objectives. The use objectives call for maintaining full recreational use and coldwater sport fisheries for Geneva Lake. Studies conducted over the years indicate that Geneva Lake is generally meeting those objectives. Water quality standards supporting warm water fishery and full recreational use objectives apply to the surface waters and concentrations measured at spring when the lake water is mixing. These standards are listed in Table 2.

Table 2: Recommended Water Quality Standards to Support Recreational, Warm water Fish and Aquatic Life.
Water Quality Parameter Water Quality Standard
Maximum Temperature 89°F
pH range 6.0 - 9.0 units
Minimum Dissolved Oxygen 5.0 mg/l
Maximum Fecal Coliform 200/400MFFCC/100 ml a
Maximum Un-ionized Ammonia Nitrogen 0.02 mg/l
Maximum Total Residual Chlorine 0.01 mg/l
Maximum Total Spring Phosphorus 0.02mg/l
Other --- b
a The membrane filter fecal coliform count per 100 ml shall not exceed a monthly geometric mean of 200 colonies per 100 ml based on not less than five samples per month, nor a level of 400 per 100 ml in more than 10% of all samples during the month
b Unauthorized concentrations of substances are not permitted that alone or in combination with other material present are toxic to fish or other aquatic life or interfere with recreational use. Floating or submerged debris, oil, scum or other material shall not be present or deposited on the shore or bed of the lake nor shall they interfere with public rights in the water or be harmful to aquatic life.

GENEVA LAKE’S MANAGEMENT PLAN

In the summer of 2008 a detailed and comprehensive Lake Management Plan for Geneva Lake was prepared by Southeastern Wisconsin Regional Planning Commission for the Geneva Lake Environmental Agency. A major component of any lake management plan is the land use plan within the lake’s watershed. Water pollution problems and their solutions are strongly linked to people’s activities in the watershed. Thus a good land use plan must consider and address the type and location of land uses as they will determine the character, magnitude and distribution of non point pollution sources. Geneva Lake’s land use plan as presented below complements and refine the adopted regional water quality management plan, the regional land use plan and the Walworth County land and water resource management plan.

Geneva Lake Watershed use 2020

Major components and recommendations of Geneva Lake’s management plan are:
  • Land Use
    • Local communities adopt zoning guide lines set forth in the regional land use and County development plans.
    • Historic lake front dwelling densities and setback requirements are maintained
    • Establish strong storm water management ordinances with periodic review.
    • Protect environmentally sensitive and unique lands.
  • Pollution Abatement
    • Good urban and rural nonpoint source pollution abatement throughout the entire watershed.
    • Promote urban housekeeping and yard care practices through public education.
    • Uniformly develop and enforce strong construction site erosion control and storm water management.
    • Conduct periodic review and refinement of sewer service area needs within sewered areas.
    • Implement strong onsite sewage disposal system management to include inspection, maintenance, replacement and education.
  • Water Quality and Quantity
    • Continue on going lake water quality monitoring program.
    • Watershed monitoring as needed.
    • Continue Municipal beach bacterial testing.
    • Additional studies as needed to better understand the lake and its biota.
    • Better understand and retain the lake/groundwater relationship.
  • Aquatic Biota
    • Maintain and protect all fish habitat especially shoreline and littoral zone fish habitat.
    • Continue stocking of selected game fish and monitoring of rough fish population.
    • Implement aquatic plant management plan with updated plant surveys.
    • Clean up floating plant fragments.
    • Continue to monitor for invasive species and their distribution.
  • Water Use
    • Enforce boating and pier regulations.
  • Information and Education Programs on:
    • Aquatic Plant Management
    • Invasive species
    • Safe recreational use
    • The need for shoreline protection
    • Watershed awareness
    • Centralized and decentralized wastewater management
    • Lake stewardship

COSTS

Many of the recommended management efforts are extensions of on-going efforts already being carried out by the communities and local organizations. Thus some of their costs are already being covered. Refinement and upgrading some of these efforts may require additional funding. Other costs can be offset by grants and cost share programs at the State and Federal level.

To put an exact cost of the implementation of this plan is difficult as it will depend upon the number of acres involved in individual practices, the amount of volunteers and the effort individual land owners are willing to commit. The complete Lake Management Plan for Geneva Lake estimates a 2000 – 2020 capital cost of $303,600 and an annual operation and maintenance cost of $181,600 for plan implementation.


This summary report was prepared by the Geneva Lake Environmental Agency with funding from the Lake Geneva Garden Club. It represents the Agency’s summary of the Lake Management Plan for Geneva Lake, Community Assistance Planning Report NO. 60, Second Edition, prepared by Southeastern Wisconsin Regional Planning Commission under a Wisconsin Department of Natural Resources Lake Management Planning Grant. The GLEA is thankful to all who helped make this report and summary possible.