Delavan Lake Water Quality

Water Quality Dashboard



Secchi Depth

Lake Conditions

  • Live Updates

  • Weekly Weather Forecast

  • Water Temperature 

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Delavan Lake

Sanitary District


Delavan Lake USGS

The Delavan Lake Quality dashboard provides a visual representation of the health of our lake using three key measures Phosphorus, Chlorophyll, and Secchi depth. The colors and arrows on the dials show current water quality based on last available data. The dials on this site are updated approximately every 2 weeks depending on weather conditions. The purpose of this dashboard is to create awareness and easy access to Delavan Lake water quality information. We invite, welcome your suggestion and ideas as to improve this site.


Dashboard Parameter Definitions and Goals:

Phosphorus: Is a nutrient that contributes to excessive aquatic plant and algae growth. Sources of phosphorus include fertilizer from farm fields and lawns. Goal: keep surface phosphorus concentrations below 34 ug/L.

Chlorophyll: A measure of the concentration of algae in the lake. Goal: keep surface chlorophyll a concentrations below 15 ug/L.

Secchi Depth: A measure of water transparency. It shows the depth that a black and white disk can be seen the surface. Goal: keep clarity greater than 1.5 meters.

information. We also hope to use it as and information source regarding all Lake matters.


The current goals for Delavan Lake water quality were established as part of a University of Wisconsin Water Resources Management Workshop conducted in 1986.


More Information…

Delavan Lake is a 2,072-acre drainage lake. Its watershed is approximately 26,3125 acres. Its primary source of water is Jackson Creek. Although the lake's excess nutrients no longer result in the large blue-green algae mats of the 1970s and 1980s, excessive populations of Eurasian water milfoil are now problematic.

Why Worry About Water Quality? 


There are many reasons beyond the weeds and occasional algal bloom that impact recreation. The water quality of Delavan Lake influences our property values. Many studies conducted all over the country have shown the relationship between property values and water quality.


Current Monitoring Program


Since the completion of the Rehabilitation project the Town of Delavan and the Delavan Lake Sanitary District have maintained an ongoing water sampling program. The USGS conducts most of the sampling and subsequent analysis. The USGS monitoring program is rigorous and consistent program with approximately monthly sampling of the lake for various water quality and biological parameters from April through October and sampling in Jackson Creek at Mound Rd approximately 80 times per year. All USGS monitoring information can be found Click Here.


The DLSD, as part of the Wisconsin Citizen Monitoring Program of the Wisconsin DNR, also measures phosphorus and chlorophyll monthly during June-September, and measures Secchi depths every other week through the summer and early fall. Lake levels are measured by the DLSD and are important in establishing Slow No Wake declarations and serve as an advance warning for pier damage.


To see a presentation of the Current State of Delavan Lake: Click Here


The Lake Restoration Project


A restoration of Delavan Lake conducted was conducted in the late 1980s at a cost of over $7,000,000 or $13,000,000 in today’s dollars. It was one of the most comprehensive lake rehabilitation projects ever undertaken in the world. It was implemented by local citizens, governmental units, the University of Wisconsin, Wisconsin Department of Natural Resources (WDNR), U.S. Geologic Survey (USGS) and U.S. Environmental Protection Agency. Specific components of the project included: constructing upstream ponds to capture sediment and nutrients, short circuiting nutrients coming into the lake from Jackson Creek; removing all rough fish (carp) with the chemical rotenone; and treating the lake bottom to reduce nutrient exchange between lake sediments and lake water. For more information, Click Here.


All of us should be aware of and actively support the ongoing efforts of the Town of Delavan, the Delavan Lake Sanitary District, USGS and WDNR to evaluate, maintain, and improve lake water quality. We will work to keep you apprised about these activities on these pages.


5621 Town Hall Road

Delavan, Wisconsin


Mon - Fri – 8:30am - 4:30pm

Phone: 262-728-3471



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