From cyanobacteria (blue-green algae) blooms, to elevated bacteria (E. coli) levels, to flooding, our lakes have had a tough season. With our lakes facing so many obstacles, it makes Clean Lakes Alliance even more appreciative of its volunteers.
Unveiled and launched at a May 18, 2022, public release party hosted by Clean Lakes Alliance, “Renew the Blue” is a cross-sector partnership initiative that commits to untapping the full potential of Greater Madison’s lakes. The initiative, developed and led by a diverse coalition of 19 community groups, offers an updated blueprint for cleaner lakes and beaches. If you love the lakes and care about their future, Renew the Blue calls upon you, our fellow stakeholders, to lead by example and play a role in the solutions.
The Yahara Watershed and its five lakes define Dane County and Greater Madison’s sense of place. Lakes Mendota, Monona, Wingra, Waubesa, and Kegonsa contribute significantly to the region’s economic vitality, recreational offerings, and local quality of life. Clean and healthy lakes are truly a benchmark of a healthy community.
Investments over the years have laid the foundation for future water quality improvements. However, our lakes remain federally impaired for failing to meet basic water quality and use standards. Land use and climate impacts, such as heavy rain and runoff, and other headwinds threaten our progress.
The Yahara CLEAN Compact is a coalition of partners and collaborators who are working to improve the condition and usability of our lakes and beaches. It does this by expanding and strengthening the community partnership to clean up our lakes, and by uniting around a common vision and action plan to which we can be accountable. Ultimately, it is a promise to build on our past successes and cooperatively deliver the needed solutions and actionable timelines that will improve water quality.
Click the image on the left to download information about the Yahara CLEAN Compact. (Note that the Greater Madison Lakes Survey was administered in 2021 to help inform the planning work and is no longer active.)
Clean lakes won’t happen overnight. Progress requires a clear plan and dedicated coalition of organizations and resources. In 2008, Dane County, City of Madison, Wisconsin Department of Natural Resources, and Wisconsin Department of Agriculture, Trade and Consumer Protection launched a lake cleanup partnership called Yahara CLEAN (Capital Lakes Environmental Assessment and Needs). Two years later, the group released a report outlining 70 recommendations. The recommendations sought to reduce phosphorus and E. coli contamination that can negatively impact water quality and close our beaches (Yahara CLEAN 1.0).
In 2011, Clean Lakes Alliance reconvened the Yahara CLEAN partners to turn the list of 70 recommendations into a streamlined action plan with clear goals, costs, and metrics. The partners hired an engineering firm to identify the 14 most cost-effective, ready-to-implement projects and practices to help reach a 50% phosphorus reduction goal (Yahara CLEAN 2.0). If successful, UW Center for Limnology scientists estimated a doubling of the number of summer days when our lakes are clear and free of algae blooms.
In 2016, Clean Lakes Alliance evaluated the pace of community progress in carrying out the recommended action priorities set forth in the 2012 plan. The analysis showed that we would not reach our goals anytime soon, suggesting more would need to be done at a faster pace (Vision 2025 Analysis). This understanding was reaffirmed in 2018 when the Dane County Board of Supervisors approved a Healthy Farms Healthy Lakes (HFHL) Task Force recommendation to update our community lake-cleanup plan.
In 2019, after six years of promoting action and tracking our community’s progress, Clean Lakes Alliance reconvened and expanded the Yahara CLEAN partnership to update the cleanup plan. Called the Yahara CLEAN Compact (see Letter of Intent page 1 and page 2), coalition members sought to account for accomplishments and progress to date, re-evaluate phosphorus reduction targets, and set forth revised strategies, costs and timelines to complete the needed work (Yahara CLEAN 3.0). The Compact’s overarching goal is to make our lakes swimmable again. At the same time, it aims to promote a culture of watershed sustainability that will benefit this and future generations.
Partners are voting members of the Executive Committee under the Compact, providing agreed upon staff and financial resources to facilitate the Yahara CLEAN updating process. A two-year, annual contribution of $25,000 ($50,000 total) is requested from each partner to help pay for related costs. Represented by an appointed lead designee and co-designee, partners are expected to:
1) participate on the Executive Committee to make decisions related to budget, consultant hires, final recommendations, and project deliverables; commit to send a representative to at least 5 of every 7 Executive Committee meetings;
2) participate on the Steering Team to finalize the scope of work and oversee its implementation;
3) participate on Subgroups as needed to gather detailed or technical information and to provide analysis and deliberation;
4) assist in the development of as-needed Requests for Proposals, and vote on the selection of any needed consultants with contracts executed by Clean Lakes Alliance;
5) furnish agreed upon information, staff support, and financial resources helpful to the effort;
6) provide input and direction to any contracted consultants;
7) agree to a public communication strategy and process;
8) sign off on any final recommendations and project deliverables produced under this Compact; and
9) support and work to implement the updated plan upon its completion.
Collaborators are supporting agencies or organizations that often play a significant cooperating role in reducing watershed phosphorus and/or achieving water quality improvements. A two-year, annual contribution of $1,000 ($2,000 total) is requested to demonstrate full investment in the effort and to help pay for related costs. Collaborators are provided opportunities for input and information sharing, but are not voting members of the Executive Committee under the Compact. Represented by an appointed lead designee and co-designee, collaborators are expected to:
1) participate on the Steering Team to provide guidance and information to the Executive Committee on goals, scope of work, consultant hires, final recommendations, project deliverables, and public outreach; commit to send a representative to at least 3 of every 4 Steering Team meetings;
2) participate on Subgroups as needed to gather detailed or technical information and to provide analysis and deliberation;
3) share information, perspectives, guidance, and advice within the Steering Team and Subgroups, and as needed with contracted consultants; and
4) support and work to implement the updated plan upon its completion.
All collaborators serve on the Steering Team. The Steering Team is an advisory body, which uses a gradient-of-agreement tool to get a sense of the group, and to share its members’ expertise, perspectives, and guidance with the Executive Team.
We are fortunate that our community is coming together like never before in a shared effort to improve the lakes. Through the work of the Yahara CLEAN Compact, renewed momentum and new opportunities are being leveraged, effectively building on past success and giving us all a role to play.
The project steering team consisting of appointed partner and collaborator designees met monthly for more than two years starting in August of 2019. The team’s work included a re-evaluation of the state of the science, a multi-faceted public engagement process, and the eventual development of a stakeholder action guide, titled Renew the Blue: A Community Guide for Clean Lakes & Beaches in the Yahara Watershed.
Phases of the Compact followed the Yahara CLEAN Compact Logic Model.
We extend our heartfelt gratitude for your support in ensuring that this year’s Clean Lakes Community Coffee was a resounding success! This cherished event, held every other year, serves as a platform to foster unity within our community, provide educational opportunities, and enhance awareness about the significance of our lakes. Your participation has truly made a difference in highlighting the importance of preserving and protecting this vital natural resource for current and future generations.
Clean Lakes Alliance, along with SRF Consulting Group, the University of Wisconsin-Madison, and the University of Wisconsin-Whitewater, completed a first-of-its-kind study to determine the economic impact of the Yahara chain of lakes on the Greater Madison community. The study reveals how our lakes and their conditions impact tourism, real estate, and quality-of-life factors. Investing in the protection and improvement of lake quality can pay dividends felt throughout the region.
The Yahara lakes region, called Teejop (meaning “Four Lakes”) by the native Ho-Chunk, has drawn people to its vast lakeshores for thousands of years. Since the end of the last ice age, the lakes have shaped how people live, work, and play. Humans living in this region have both benefited from and impacted the lands and waters of Teejop.
Have you ever considered what our Greater Madison communities would be like without these lakes? Is it even possible to put a value on all the public benefits they generate? What price tag would you place on clean water, natural scenic beauty, biological diversity, or any of the countless quality-of-life attributes that make this lake-rich area so special? More importantly, what happens to those benefits if lake conditions improve or deteriorate?
Clean Lakes Alliance partnered with a team of economists and other experts to try to answer these questions. The findings proved to be nothing short of eye-opening. The lakes are a true driving force in our local economy.
Today, the Yahara lakes support 1,802 full-time-equivalent jobs and annually contribute a staggering $220.1 million to the Greater Madison economy! This is a conservative estimate that equates to $2.2 billion every decade.
Lake-related businesses and tourism thrive when water conditions are healthy. In 2023 alone, residents made an estimated 2.7 million visits to the Yahara lakes. These visits fuel local restaurants, shops, and outdoor recreation businesses. But population surveys conducted as part of the study found that nearly 82% of respondents are “very or extremely concerned” about cyanobacteria blooms in the lakes. And they are not wrong. Poor water quality comes at a steep price: Dane County loses more than $3.2 million in economic benefit for every cyanobacteria (blue-green algae) bloom day.
Property values in particular are directly linked to water quality. Homes closer to the lakes are worth nearly 49% more due to their proximity, and a 12-inch drop in water clarity across all five lakes would reduce home values by nearly $80 million. This means that as lake conditions change, impacts reverberate through the regional housing market.
Just as we see the lakes respond quickly and favorably to phosphorus reductions, we also see economic benefit when water quality improves. Clearer water means more open beaches, more visitors, and more revenue for local businesses. An additional 19 summer days without a cyanobacteria bloom or beach closure can generate an estimated $75 million per year in additional economic benefits.
These figures paint a clear picture: The health of our lakes is directly tied to the strength of our economy. By working together to protect and restore them, we’re not only safeguarding a natural resource, we are also ensuring that our local businesses, property values, and outdoor spaces continue to thrive.
Each of us can play a role in keeping our lakes clean and preserving their value. Start small by checking out Clean Lakes Alliance’s Top 10 Ways to Help the Lakes at Home — simple steps like reducing runoff, keeping leaves out of street gutters, and supporting lake-friendly businesses. Or consider becoming a donor to help support ongoing efforts to protect and restore our lakes. Finally, make your interests known by advocating for water quality-protective policies and investments. Your elected representatives want to hear from you as their constituents, and starting local is a great way to push for action around recommendations outlined in RENEW THE BLUE: A Community Guide to Cleaner Lakes & Beaches in the Yahara Watershed.
Healthy lakes create thriving communities. By investing in water quality, we’re investing in the future of Greater Madison — one that continues to benefit from thriving businesses, strong property values, and swimmable, fishable waters for generations to come.
To view Clean Lakes Alliance’s Top 10 Ways to Help the Lakes at Home, please visit: cleanlakesalliance.org/top10
Learn more about Clean Lakes Alliance’s Teejop Initiative: cleanlakesalliance.org/teejop-initiative
The State of the Lakes provides an annual health synopsis of Greater Madison’s five Yahara lakes (Mendota, Monona, Wingra, Waubesa, and Kegonsa). The chain of lakes and the land areas that drain to them are shown in Figure 1 below. Focusing on major drivers and indicators of water quality, the following analysis summarizes lake and watershed health factors, trends, and the likely causes of observed conditions. The report begins with a “health dashboard” for each lake before delving into five areas of watershed-impact and lake-response analysis.
Authored by Clean Lakes Alliance Deputy Director and Chief Science Officer Paul Dearlove, this report is a product of collaboration involving multiple government and scientific contributors. We are grateful to the following information sources: U.S. Geological Survey, University of Wisconsin-Madison, Wisconsin Department of Natural Resources, Public Health Madison & Dane County, Dane County Land & Water Resources Department, and Clean Lakes Alliance’s volunteer LakeForecast monitors.
Lake Type: Drainage
Direct Drainage Area: 217 sq. miles
Total Drainage Area: 232.4 sq. miles
Surface Area: 9,847 acres
Shoreline Length: 22 miles
Mean Depth: 42 feet
Maximum Depth: 83 feet
Volume: 133,407 million gallons
Flushing Rate: 22% of volume/year
Lake Mendota sits at the top of the chain and is the largest of the five Yahara lakes by surface area, depth, and volume. Its direct drainage area consists predominantly of agricultural land uses. Inlet tributaries include Pheasant Branch Creek (west shore); and Sixmile Creek, Dorn Creek, Token Creek, and the Yahara River (north shore). The lake’s outlet (southeast shore) directs overflow water through the Yahara River and into Lake Monona. It has been listed as impaired under the Clean Water Act for phosphorus since 2011.
Lake Type: Drainage
Direct Drainage Area: 40.5 sq. miles
Total Drainage Area: 278 sq. miles
Surface Area: 3,277 acres
Shoreline Length: 13 miles
Mean Depth: 27 feet
Maximum Depth: 74 feet
Volume: 29,059 million gallons
Flushing Rate: 91% of volume/year
Lake Monona is the second largest of the five Yahara lakes by surface area, depth, and volume. It sits immediately downstream of Lake Mendota in the upper half of the chain. The lake’s direct drainage area consists mostly of urban land uses. Inlet tributaries flowing into the lake include Murphy’s (Wingra) Creek (west shore); the Yahara River (north shore); and Starkweather Creek (northeast shore). The lake’s outlet (south shore) directs overflow water through the Yahara River and into Upper Mud Lake and Lake Waubesa. It has been listed as impaired under the Clean Water Act for PCBs since 1998, total phosphorus since 2011, and PFAS since 2022.
Lake Type: Drainage
Direct Drainage Area: 5.4 sq. miles
Total Drainage Area: 5.4 sq. miles
Surface Area: 321 acres
Shoreline Length: 3.7 miles
Mean Depth: 9 feet
Maximum Depth: 14 feet
Volume: 1,585 million gallons
Flushing Rate: 77% of volume/year
Lake Wingra is the smallest of the five major lakes by surface area, depth, and volume. Originally a deep-water marsh, this dredged waterbody now flows into Lake Monona via Murphy’s (Wingra) Creek. The lake’s direct drainage area is located entirely within the city of Madison and dominated by urban land uses. Three minor, unnamed inlet tributaries flow into the lake at points along its west and southwest shore. It has been listed as impaired under the Clean Water Act for total phosphorus since 2011 and PCBs since 2012.
Lake Type: Drainage
Direct Drainage Area: 43.6 sq. miles
Total Drainage Area: 325 sq. miles
Surface Area: 2,083 acres
Shoreline Length: 9.4 miles
Mean Depth: 15 feet
Maximum Depth: 38 feet
Volume: 10,567 million gallons
Flushing Rate: 320% of volume/year
Lake Waubesa is the fourth largest of the Yahara lakes by surface area and volume. It sits immediately downstream of Upper Mud Lake and Lake Monona in the lower half of the chain. The lake’s direct drainage area is represented by a mix of urban and rural/agricultural land uses. Inlet tributaries that drain into the lake include Nine Springs Creek and Penitto Creek (flowing into Upper Mud Lake to the north); the Yahara River (north shore); as well as Swan Creek and Murphy’s Creek (southwest shore). The lake’s outlet (east shore) directs overflow water through the Yahara River and into Lake Kegonsa. It has been listed as impaired under the Clean Water Act for phosphorus since 2011 and PFAS since 2022.
Lake Type: Drainage
Direct Drainage Area: 54.4 sq. miles
Total Drainage Area: 384.6 sq. miles
Surface Area: 3,210 acres
Shoreline Length: 9.6 miles
Mean Depth: 17 feet
Maximum Depth: 32 feet
Volume: 17,700 million gallons
Flushing Rate: 220% of volume/year
Lake Kegonsa is the third largest of the Yahara lakes by surface area and volume. It sits immediately downstream of Lake Waubesa and Lower Mud Lake in the lower half of the chain. The lake’s direct drainage area consists predominantly of rural/agricultural land uses. Inlet tributaries to the lake include the Yahara River and Door Creek (north shore) and two unnamed creeks (southwest and northeast shore). The lake’s outlet (east shore) directs overflow water through the Yahara River toward the Rock and Mississippi Rivers. It has been listed as impaired under the Clean Water Act for total phosphorus since 2011 and PFAS since 2022.
The State of the Lakes assesses five areas of interest that represent vital, interconnected pieces of the larger water quality puzzle. Illustrated in Figure 2, they include both outputs (i.e., land-use actions taken) and outcomes (i.e., measured water quality responses). Each was chosen to illustrate critical cause-and-effect principles that play out as water interacts with and gets funneled through the watershed.
The availability and movement of phosphorus are central themes given its dominant role in affecting overall lake conditions. Although a natural element essential for plant and animal growth, it can easily harm water quality due to excess supply and poor management. Sources of phosphorus can include eroded soil, fertilizer runoff, leaf debris in city streets, livestock manure, sewage releases, and improperly disposed pet waste. A common rule of thumb is that it takes only one pound of phosphorus to generate up to 500 pounds of algae growth.
Regardless of whether it is a change in average temperature, precipitation, ice cover, or some other factor, lakes dynamically respond to their environment. Regional heating and cooling patterns influence what types of aquatic organisms can thrive, how and when the water column mixes, and the timing and magnitude of annual freeze cycles. Meanwhile, the timing, intensity, and amount of rainfall over the watershed determine what can get moved from the land surface into our waters, including phosphorus-containing materials that fuel algal growth and turn the lakes green.
Winter ice conditions and the timing of ice-off influence everything from a lake’s thermal properties to the reproductive success of its aquatic life. Ice quality and overlying snow depth affect how much sunlight can penetrate to warm the water column and facilitate dissolved oxygen production through photosynthesis. Research by Dr. Zachary Feiner at UW-Madison’s Center for Limnology documents the impacts of early ice-off. As ice-off dates move earlier due to climate change, algae production gets an earlier start and then collapses right when certain types of zooplankton hatch and are looking for food. That means fewer zooplankton to graze on algae or feed juvenile fish. Resulting impacts can range from poorer walleye recruitment to more intense algal blooms.
During the winter of 2023-24, Lake Mendota remained frozen for only 44 days, resulting in 54 fewer days of ice cover compared to the preceding year. This was the second shortest duration of ice cover for Lake Mendota based on the last 169 years of Wisconsin State Climatology Office recordkeeping. Historical evidence shows ice-cover durations in decline, with Lake Mendota having lost about a month of ice cover since recordkeeping began.
Shorter and warmer winters lead to warmer lake temperatures earlier in the year, effectively creating a longer growing season for algae and aquatic plants. Warmer winters can also contribute to greater runoff and phosphorus delivery when wet precipitation falls on frozen soils. Rather than soak into the ground, rainfall more easily turns into runoff that can carry land-spread manure and other contaminants into the ditches and streams that drain to the lakes. It is estimated that, on average, nearly half of the total phosphorus loading through Lake Mendota’s monitored stream tributaries occurs from January to March, making late winter and early spring a vulnerable time for our lakes.
A total of 46.45 inches of precipitation fell across the watershed during the 2024 water year (Oct. 1 – Sep. 30). This is a 20% increase over the 37.13-inch historic normal. As shown in Figure 3 below, May through September’s collective rainfall totaled 30.81 inches, compared to the normal 21.48 inches during this period over the last 30 years. The heavier precipitation led to higher lake levels, reversing what was experienced during the recent drought years that kept water levels low.
May, June, and July each registered several days with rainfall greater than one inch. July experienced significant runoff events, with July 2nd dropping 2.49 inches of rain and July 13th-14th recording 4.69 inches in less than 48 hours. Large, “gully washing” rain events like these were more frequent, contributing to increased soil erosion and flooding throughout the watershed. Wetter years like 2024 also speak to the impacts that runoff has on phosphorus loading, water clarity response, and algal bloom frequency. More stormwater moving across the landscape means more opportunity for pollutants to wash into our lakes. Because of an unusually warm winter followed by high spring rainfall totals, the lakes received much higher phosphorus inputs compared to the recent drought years.
Calculating the difference between the mass of phosphorus entering (imported into) and leaving (exported from) the watershed tells us whether the net balance is trending in the right direction. The movement and fate of livestock, feed, fertilizer, harvested crops, animal waste, and other phosphorus sources are factored into the analysis. The goal is to attain a negative balance, indicating more phosphorus is being exported than imported on an annual basis. This situation reduces the overall availability of phosphorus from being able to reach area waterways.
Conversely, a positive balance signals an annual net accumulation of phosphorus in the watershed, usually leading to its gradual buildup in area soils. Phosphorus-saturated soils subject to erosion from disturbance or a lack of protective, year-round plant cover can eventually end up at the bottom of nearby lakes and streams. Phosphorus is also more easily “leached” (or released in dissolved form) from these soils when they encounter rainwater and snowmelt.
Past improvements to the overall mass balance are attributed to multiple factors. They include decreases in imported commercial fertilizer, less phosphorus-containing feed supplements consumed by livestock, exported byproducts of manure digestion, and advanced phosphorus-management strategies implemented by Madison Metropolitan Sewerage District (among others). Examples of mass balance detractors include increases in livestock numbers and milk production that lead to more manure.
The implementation of land conservation practices is critical in our efforts to improve water quality. Practices such as perennial grasslands, vegetative buffers, cover crops, and rotational grazing are prime examples of solutions that reduce the amount of soil and nutrient runoff reaching nearby surface waters. Another critical conservation practice aiding in reducing these losses is the implementation of nutrient management plans.
Nutrient management plans are a tool that allows farmers to evaluate different cropping, tillage, and nutrient applications (i.e., fertilizer and manure) to optimize crop production while minimizing runoff risks. Records filed with Dane County Land & Water Resources in 2024 indicate that 44,830 out of 84,321 total agricultural acres within the Yahara lakes watershed (53%) were mapped as having a nutrient management plan (Figure 4). This was roughly the same amount reported in 2023. Since Dane County does not receive plans from every farm on an annual basis, the reported percentage of agricultural land having a nutrient management plan is likely to be considerably higher but still short of the goal.
One of the key environmental metrics within nutrient management plans is the Rotational Average Phosphorus Index (PI), representing estimated pounds of phosphorus loss per acre per year. The higher the PI value the greater the risk for phosphorus to reach surface waters. State standards require all agricultural fields to have a PI of 6 or less. However, based on modeling summarized in RENEW THE BLUE: A Community Guide for Cleaner Lakes & Beaches in the Yahara Watershed (2022), a Rotational Average PI of 2.1 or less is needed to reach phosphorus loading targets and water quality goals. Based on information from nutrient management plans submitted in 2024, the average PI for fields within the Yahara lakes watershed was 2.4.
Most phosphorus is delivered to the Yahara chain of lakes through tributary streams that collect and funnel upland-generated runoff as it moves downhill. How much is transported depends on the seasonal timing and intensity of runoff events, the location and availability of major phosphorus sources, and measures taken to contain those sources and manage runoff. Over the past 12 years, 43% of the total phosphorus entering Lake Mendota through its monitored tributary streams occurred during the three months of January, February, and March.
Stream monitoring helps evaluate the effectiveness of conservation practices by tracking changes in phosphorus loading. Loading describes the total mass of phosphorus entering a water body over a specific period of time. In our case, we characterize loading in pounds of phosphorus (calculated by multiplying in-stream concentrations by streamflow) delivered to Lake Mendota through its monitored stream tributaries in a given water year.
Perched at the top of the chain and receiving most of the drainage from the Yahara lakes watershed, the condition of Lake Mendota offers a good indicator for how the downstream lakes will be impacted. Lake Mendota is also the largest lake with the greatest number of monitored streams and the most complete long-term dataset. Most of the phosphorus received by the lower lakes in the chain is through the outlets of the upper lakes as it cascades through the system.
Figure 5 shows the change in stream-monitored phosphorus loading since 2013. Total precipitation is also plotted in orange to distinguish between wet and dry years. From 2021-2023, average annual phosphorus loading to Lake Mendota significantly declined and even managed to dip slightly below target levels. This was largely due to the three-year period of drier weather that followed years of above-average precipitation, reducing the amount of runoff able to transport phosphorus to the lakes. Scientists estimate a doubling of summer days when the lakes are clear and free of algal blooms if these lower levels can be maintained. Unfortunately, a wetter-than-normal 2024 helped erase many of those earlier gains, highlighting the value of land practices that reduce runoff and the sources of excess phosphorus.
Several in-lake metrics are used to assess overall lake health and track changes over time. Those metrics include water clarity, phosphorus concentration, presence of cyanobacteria (blue-green algae) blooms, and beach closures. Each is summarized in the following sections. Four of the five lakes dropped to a “fair” ranking for phosphorus and clarity in 2024. Lake Wingra, which ranked “good” on both measures, was the lone exception.
After falling precipitously during the recent drought years of 2021-2023, in-lake phosphorus concentrations jumped in all the lakes except for Lake Wingra (Figure 6). No obvious trends are evident in any of the lakes when looking at longer time horizons. When averaged across individual decades beginning in 1980, lakes Monona and Waubesa show very slight downward trends while those for lakes Mendota and Kegonsa are not evident. This speaks to the reality that more work is needed to reduce phosphorus loading, the main culprit that is restricting sustained water quality improvements.
After Lake Mendota’s phosphorus concentrations following fall turnover hit record lows in 2022 and 2023, a much wetter 2024 saw these very positive, low-runoff effects start to disappear (Figure 7). Turnover occurs when deeper lakes cool to the point where the water column can completely mix. Higher phosphorus concentrations that have built up throughout the summer in the lake’s bottom waters are then mixed throughout the lake. When less phosphorus enters the lake from the watershed, the bottom-water buildup of phosphorus is reduced, thereby reducing internal (in-lake) sources that can fuel algal growth the following year.
Fall-turnover phosphorus concentrations were especially low in 1988, 2012, and 2023 following those extended drought periods. The findings confirm that Lake Mendota’s phosphorus levels decline when watershed sources are reduced, resulting in significant and relatively quick water quality improvements.
Offshore water clarity measured in all five lakes dropped in 2024, giving up the earlier gains made from the low-runoff years of 2021-2023 (Figure 8). When looking at longer time horizons, no clear trends are readily discernable. When averaged across individual decades beginning in 1980, lakes Mendota and Waubesa show very slight downward trends while those for lakes Monona and Kegonsa are not apparent.
Because water clarity often varies across a given lake, Clean Lakes Alliance uses a network of trained monitors to collect additional data through its LakeForecast program. From Memorial Day through Labor Day, monitors submit at least twice-weekly reports on water clarity, water temperature, and the severity of observed green algae and cyanobacteria blooms (among other variables). Collected information can be seen in real-time on LakeForecast.org, allowing the public to stay up to date on current lake conditions. These reports are also used to raise awareness about changing water quality conditions, advocate for improvement projects, and to prepare the annual State of the Lakes.
To measure nearshore clarity, monitors use a sampling device called a turbidity tube to report conditions at 81 sites around all five lakes (Figure 9). Figure 10 on the following page shows the median summer (Jul-Aug) clarity readings for each lake from 2014-2024. Values under 50 are considered “murky,” between 50-80 “fair,” and between 80-120 “good.” Values for 2024 fell within the fair to good range. Lake Waubesa was reported as having the highest nearshore clarity while Lake Kegonsa had conditions bordering on murky. Comparing nearshore to offshore findings highlights how clarity can vary over both time and space within individual lakes, and why both assessments are provided in this report.
To determine cyanobacteria bloom frequency, the number of days on each lake with at least one report of a strong cyanobacteria bloom observed within the monitoring sites was counted. By dividing the number of “cyanobacteria bloom days” by the total number of sampling days for each lake, a percentage is generated representing how often the monitors observed at least one major bloom within their nearshore sampling area. This method lessens overreporting in situations when different monitors report the same cyanobacteria bloom.
Figure 11 shows the percentage of sampling days when strong evidence of a cyanobacteria bloom was observed on each lake (2014-2024). Overall, monitors reported comparatively high cyanobacteria blooms during the 2024 sampling period (Jun-Aug). Monitors on Lake Wingra did not report a single significant bloom, while those on Lake Kegonsa reported a program-record number of sightings.
Beach closures are another useful indicator of general lake health. Clean Lakes Alliance looks at closure data provided by Public Health Madison & Dane County for 17 beaches (Figure 12). Covering four of the five Yahara lakes, these tested public beaches were selected for analysis due to the consistency of tracking data over the reporting period. Results are reported as total closure days recorded for each season, roughly running from Memorial Day to Labor Day. For example, if two beaches on a given lake are closed for a total of five days each, 10 closure days would be reported for that lake.
Closures are most often the result of high cyanobacteria and/or E. coli bacteria levels, with closure rates strongly influenced by timing and frequency of testing. Most beaches are tested once per week and then daily for beaches with a closure in effect. Cyanobacteria blooms, which are generally a product of high lake fertility, can be dangerous due to their potential to release toxins that can harm people, pets, and wildlife. High E. coli bacteria concentrations can also be harmful as they are an indicator of human or animal fecal matter in the water that may contain dangerous pathogens.
In 2024, there were 133 closure days among the beaches tracked for this analysis, surpassing the long-term median. E. coli was the leading cause of closures (68%) followed by cyanobacteria (32%). Tenney Park Beach on Lake Mendota was not subject to testing due to being closed for a construction project during the 2024 season.
“Filthy water cannot be washed.” – West African proverb
Water is life, and Greater Madison is a special place because of it. The water surrounding us has sustained thriving lakeshore communities for thousands of years. Long considered sacred by Indigenous cultures, the lakes reflect the stewardship legacies we choose to pass down from generation to generation.
As today’s land and water caretakers, we are each called to build upon the best of these legacies and contribute to something larger than ourselves. Clean Lakes Alliance is merely a catalyst, and we recognize that the power for change resides within each of us as individuals. As our alliance grows, so does the impact of each individual action that shapes the world in which we live. This belief is fundamental to why we are here and what kind of community we aspire to become.
To learn more, be sure to check out “Renew the Blue” and “Top 10 Ways to Help the Lakes at Home” for guidance on how to improve your stewardship credentials.
Stewardship is about making choices you can feel good about, and that are cumulative in impact. Water quality is then the result of many individual decisions occurring across a watershed.
The annual State of the Lakes is released each year as part of the Greater Madison Lake Guide. In it, we report out to the community on the state of water quality in our lakes. The report also looks at our collective progress toward our phosphorus reduction goal.
The report highlights information from many partners to share the most up-to-date science on water quality in our lakes. We feature local projects, including work in urban areas to protect stormwater quality and progress on farms to keep nutrients on the fields and out of our lakes.
In addition, we provide more information about Clean Lakes Alliance and our efforts to engage the community and advocate for the lakes. This report serves as a reference and a resource, highlighting community progress toward cleaner, healthier lakes for all.
Learn more about lakes Mendota, Monona, Wingra, Waubesa, and Kegonsa.
“The juxtaposition of a walkable, bikeable urban Madison with the natural beauty of the Yahara lakes makes this area so unique and special.”
Mike Smale
Mike joined the Clean Lakes Alliance in May 2025 as a Watershed Programs Specialist. His primary work is to assist with watershed program efforts, outreach and communication development, Renew the Blue partner engagement, board and committee facilitation, and manage the organization’s grant outreach efforts.
Before joining the Clean Lakes Alliance, Mike worked as a Philip J. Kellior Great Lakes Fellow with the Wisconsin Sea Grant and Wisconsin Department of Natural Resources (Wisconsin DNR), where he researched Lake Superior coastal wetland climate resiliency. He has also worked as a technician and crew lead for the National Aquatic Resource Surveys with the Wisconsin DNR, where he collected habitat and water quality samples from rivers and wetlands across the state.
Mike grew up in West Bend, Wisconsin, and obtained his undergraduate Geography and Environmental Studies BS degree as well as his M.S. in Water Resources Management from the University of Wisconsin-Madison. He views freshwater sciences as a highly interdisciplinary field, where no two things are truly independent from one another in watersheds: urban land use, agricultural practices, ecological management, and community engagement are all interrelated concepts that are critical to understanding how to best improve and protect our water resources.
In his free time, Mike enjoys being in and around water either swimming, kayaking, hiking, or camping, all while attempting to photograph the landscape. He loves to visit various local hidden gems, such as State Natural Areas around the Madison and Wisconsin region. When not on the move, he likes to frequent local dog parks with his young dog, Pilsner.
Clean Lakes Alliance’s LakeForecast water quality monitoring program completed its 12th season in 2024. This program is entirely volunteer-implemented, with over 100 trained monitors assessing water quality conditions from nearshore and offshore locations across all five Yahara lakes (Mendota, Monona, Wingra, Waubesa, and Kegonsa). From Memorial Day through Labor Day, volunteers recorded water clarity, air and water temperature, waterfowl presence, the extent of floating plant debris, and the severity of green algae and cyanobacteria at public beaches, lakeside parks, and private piers. Submitted data can be seen in real-time on Lakeforecast.org or our free app, allowing the public to stay up to date on current lake conditions.
Clean Lakes Alliance’s LakeForecast water quality monitoring program completed its 11th season in 2023. This program is entirely volunteer implemented, with 90 trained monitors assessing water quality conditions from nearshore and offshore locations across all five Yahara lakes (Mendota, Monona, Wingra, Waubesa, and Kegonsa). From Memorial Day through Labor Day, volunteers recorded water clarity, air and water temperature, waterfowl presence, extent of floating plant debris, and the severity of green algae and cyanobacteria at public beaches, lakeside parks, and private piers. Submitted data can be seen in real-time on lakeforecast.org or our free app allowing the general public to stay up to date on current lake conditions.
Welcome to the 10-year-anniversary edition of the State of the Lakes. Along with the original release of the Yahara CLEAN Strategic Action Plan for Phosphorus Reduction (2012), Clean Lakes Alliance has brought key implementation partners together to collaborate on advancing recommended actions and tracking our collective progress. Yearly updates are then reported as part of this annual snapshot, raising public awareness about the health of our waters and the major factors driving those conditions.
A lot can happen over a decade: floods, droughts, major project completions, new research discoveries and understandings, technological advancements, land-use change, and even aquatic invasive species infestations (read the 2022 Clean Boats, Clean Waters program update). The list goes on and on. Like canaries in a coal mine, our lakes respond to these changes in good ways and bad, signaling what is working and where we might be falling short on the path to improvement. While some of these lake responses can unfold quickly, others can take years to materialize.
Now, after 10 years of implementing the action plan, a fully updated and amended version is steering our collective efforts. Called RENEW THE BLUE: A Community Guide for Cleaner Lakes & Beaches in the Yahara Watershed (2022), this latest body of work by the Yahara CLEAN Compact recalibrates the roadmap for achieving healthy waters. Its recent signing by the leaders of 19 partnering organizations is a credit to the power of shared values, science-based planning, and broadly inclusive participation in solution-making.
In 2022, the Yahara chain of lakes generally fared well. Comparatively less runoff and phosphorus pollution were aided by a span of unusually dry weather and the continued adoption of conservation practices across the watershed. These factors, along with others, contributed to mostly good water clarity, fewer cyanobacteria-bloom sightings, and a lower number of beach closures.
Our Yahara chain of lakes lies within the lower reaches of a 385-square-mile watershed, a land-drainage basin beginning at the southern edge of Columbia County and extending south through much of Dane County, including Wisconsin’s capital city of Madison. Precipitation falling over this land area either soaks into the ground or runs off and into a network of streams or storm sewers toward the lower-elevation lakes.
Water that is able to soak into the ground recharges groundwater which feeds springs, providing dry-weather “baseflow” to streams or direct springwater to the lakes. The lakes collect and temporarily hold the inflowing surface and ground water before it exits the Yahara lakes watershed and continues its journey through the Yahara River and into the Rock River near the southern edge of Dane County. The water then enters the Mississippi River where it is sent to the Gulf of Mexico.
The largest four of the five waterbodies—lakes Mendota, Monona, Waubesa, and Kegonsa (in downstream order)—are interconnected by the Yahara River. Figure 1 shows the Yahara lakes watershed divided into smaller subwatersheds, also called subbasins or direct drainage areas, that funnel water to a specific waterbody.
Lake Mendota’s comparatively large, direct drainage area is predominantly agricultural while Lake Monona’s is mostly urban. Lake Waubesa’s is a mix of urban and agricultural, whereas Lake Kegonsa’s is predominantly agricultural. The much smaller and shallower Lake Wingra, which drains east to Lake Monona, is contained within an entirely urbanized subbasin. Together, these subbasins gather and direct surface water that then moves from one lake into the next.
The time it takes each lake to completely cycle through its volume of water ranges from 4.3 years for deeper Lake Mendota to only 2.8 months for shallower, downstream Lake Waubesa. These flushing rates for each lake increase during wet, high-runoff years and decrease during drought years.
The five Yahara lakes have a complex relationship with their surrounding watershed. Much has been learned about this relationship and the land conditions needed to sustain it. But because many variables are at play (i.e., climate, geology, soil health, land cover, land use, lake ecology, etc.), teasing out the precise causes of water quality change can often prove complicated. And because the lakes themselves exhibit their own unique characteristics, each lake can behave somewhat differently in response to internal (in-lake) and external (watershed) influences.
This report looks at five, interconnected areas of interest that represent vital pieces of the larger water quality puzzle (Figure 2). Progress-tracking metrics include a combination of outputs (i.e., actions taken, or areas affected) and outcomes (measured water quality responses), with phosphorus management as a central theme given its dominant role in generating algal growth. In general, we track phosphorus and its impact on algal abundance, water clarity, and beach closures, factors that influence the perception of water quality and the recreational suitability of the lakes.
WHY PHOSPHORUS?
Too much phosphorus harms water quality and turns the lakes green. It can be found in fertilizers (note: phosphorus lawn fertilizers are banned in Dane County), soil, animal waste, and organic material. With one pound of phosphorus capable of generating up to 500 pounds of algae, every pound matters.
Whenever applicable, the 2022 condition status is described relative to a particular water quality goal or target. Status is also compared to historical findings to provide context and reveal potential trends. This allows us to make more informed judgements regarding lake conditions, the possible factors affecting those conditions, and the overall state of progress toward our goals. Finally, each of the five areas of analysis is assigned two, color-based “scores,” one for 2022 status and one for the longer-term trend.
Weather variability and longer-term climate trends impact our lakes in many ways. For example, the timing and intensity of rainfall and snowmelt largely dictate how much runoff reaches the lakes and what it can carry along the way. Rain during a mild winter over frozen ground produces more runoff than if the rain fell during the summer when plants are actively growing. And while wetter years can transport more pollutants as surface runoff through the watershed’s drainage system and into the lakes, droughts will have the opposite effect.
Long-term climatological data show a region that is getting wetter and warmer. According to the Wisconsin Initiative on Climate Change Impacts (WICCI), the last two decades have been the warmest on record, and the past decade has been the wettest, with average annual precipitation increasing 17 percent (about five inches per year) since 1950.
Increasing rainfall volume and intensity represent an unwelcome trend that can negatively affect the performance of many conservation practices. In addition, warmer winters are leading to greater runoff and phosphorus delivery as liquid precipitation falls across frozen soils, especially where winter manure spreading occurs. The longer-term precipitation trend finally broke in 2021 and the first half of 2022. As a result of this short drought period, less surface runoff occurred, causing total phosphorus delivery to be lower than normal. This contributed to lake conditions that were generally more favorable. It speaks to the lakes’ responsiveness to reduced, external (watershed-sourced) phosphorus inputs and the rationale behind reduction goals.
Calculating the difference between the mass of phosphorus entering (imported into) and leaving (exported from) the watershed tells us whether the net balance is trending in the right direction. The goal is to attain a negative balance, indicating more phosphorus is being exported than imported on an annual basis. This situation reduces the overall availability and potential of phosphorus to reach area waterways.
Conversely, a positive balance points to an annual net accumulation of phosphorus in the watershed, usually leading to its gradual buildup in area soils. Phosphorus-saturated soils subject to erosion from farm tillage or a lack of protective, year-round plant cover can eventually end up at the bottom of nearby lakes and streams. Phosphorus is also more easily “leached” (or released in dissolved form) from such soils when in contact with rainwater and snowmelt. Dane County’s stream-dredging project, commonly referred to as “Suck the Muck,” is designed to remove this sediment-bound phosphorus that has accumulated in stream channels.
According to Eric Booth, author of Phosphorus Flows and Balances for the Lake Mendota and Yahara River Watersheds: 1992-2017, there was a notable decline in annual net phosphorus accumulation over the study period, but with plenty of room for continued improvement (Figure 3). The study looked at how much phosphorus in animal feed, fertilizer, and other phosphorus sources was imported annually into each watershed compared to how much phosphorus was leaving through the export of crops, livestock products, manure compost, and stream outflow. The difference between inputs and outputs is the change in storage or mass balance for the given watershed.
The most precipitous decline, observed between 1997 and 2002, is attributed to a decrease in imported commercial fertilizer and less phosphorus-containing feed supplements consumed by livestock. However, a growth in livestock numbers and milk production beginning in 2002 caused earlier declines to flatten or reverse, even masking the positive effects of advanced phosphorus-management and removal strategies implemented by the Madison Metropolitan Sewerage District. While bans on phosphorus-containing lawn fertilizers (2005) and household detergents (2007) helped to moderate these livestock-production impacts, it was the start of Dane County-subsidized manure digestion and associated compost export (2012) that saw accumulation rates begin to once again trend downward for both watersheds.
Booth explains that not all phosphorus accumulation is the same. The amount of risk depends on where it is accumulating and how “slippery” it is on land. He points out that the watershed is a leaky system and phosphorus tends to move around. “Reducing the transport of that slippery phosphorus from land to water is a key strategy. While many are working diligently on this through various conservation practices, we also need to treat the strategy of reducing phosphorus accumulation as an equal complement,” said Booth. “If phosphorus accumulation is not addressed, it will pose a long-term risk to water quality and can frustrate future efforts.”
According to the Wisconsin Initiative on Climate Change Impacts (WICCI), the combination of warmer winters, wetter springs, and extreme weather events is impacting agricultural production throughout the state and overwhelming conservation practices designed to keep soil in place and protect water quality. WICCI’s latest report recommends regenerative adaptations that build landscape resiliency. Examples include preserving and increasing grasslands and natural vegetation by limiting their conversion to row-crop production or urban development; planting more cover crops on farm fields; and raising livestock on rotationally-grazed pastures.
Considerable progress has been achieved to-date with the adoption of conservation practices throughout the watershed, including among many of those listed below. Thanks to the ongoing leadership and support of many governmental, nonprofit, and private-sector partners, the cumulative effect of these actions is largely holding the line against several growing headwinds described in this report.
RENEW THE BLUE
As we move forward with Renew the Blue, several initiatives are already underway to improve our watershed.
DANE COUNTY
• Laying the groundwork to quadruple its manure-treatment capabilities (see story page 50)
• Expanded the Door Creek Wildlife Area by 128 acres near Lower Mud Lake while budgeting another $10M for future land acquisitions
• Launched the next phase of “Suck the Muck” to excavate legacy phosphorous from area streambeds, removing an estimated 25,000 tons of sediment from Sixmile Creek north of Lake Mendota
CITY OF MADISON
• Adopted a first-of-its-kind ordinance requiring that excessive residual salt be removed from public sidewalks (not specifically addressed in Renew the Blue, but important for protecting vulnerable aquatic life)
• Created its third, permeable-pavement street near Midvale Elementary School to better infiltrate runoff
• Increased native plant diversity in stormwater-treatment systems, improving runoff infiltration and pollinator habitat
YAHARA WATERSHED IMPROVEMENT NETWORK
(YAHARA WINS)
• Significantly increasing financial support to farmer-led groups working to grow participation and the cost sharing of eligible conservation practices like manure composting
TOWN OF WESTPORT
• Strengthened its stormwater and erosion-control ordinance following Renew the Blue guidelines
• Purchased and permanently protected 105 acres of conservation land stretching from Governor Nelson State Park to State Highway 113 on the north side of Lake Mendota
MADISON METROPOLITAN SEWERAGE DISTRICT
• Deploying low-disturbance biosolid injection to better protect soils while limiting erosion and phosphorus runoff on participating farms
NATIONAL, STATE, AND LOCAL REALTORS’ ASSOCIATIONS
• Financially contributing to a Clean Lakes Alliance-commissioned study quantifying the economic value and impact of the Yahara lakes (important for building awareness and action)
FRIENDS OF LAKE KEGONSA SOCIETY (FOLKS)
• Initiated expanded phosphorus monitoring around Lake Kegonsa to help pinpoint problem areas
• Continued fall leaf vacuuming around the lake in cooperation with the City of Stoughton, Town of Dunn, and Town of Pleasant Springs
One example of a practice making a big difference comes from Kyle Minks of the Dane County Land & Water Resources Department. He reports the continued increase of farmland acreage under nutrient management plans. This tool is used by agricultural producers to understand how on-farm operational decisions can improve efficiencies while minimizing soil and phosphorus loss. Based on landowner records filed with the County (an under-representation of the total amount of watershed acres under nutrient management planning), 40,547 out of roughly 97,000 agricultural acres in the Yahara lakes watershed were mapped as having a nutrient management plan in 2021 – a 25% increase over numbers mapped in 2016. Dane County is also actively working to significantly expand manure-processing capacity in the watershed, among other water quality-improvement initiatives. If successful, the increased manure treatment will help address a primary source of phosphorus pollution to the lakes, especially during late winter and early spring when manure spreading is most susceptible to runoff.
When phosphorus accumulates in the watershed, it is easier for it to build up in area soils where it puts local waterways at risk. Most phosphorus is delivered to the Yahara chain of lakes through tributary streams that collect and channel upland-generated runoff as it moves downhill. How much is transported depends on multiple factors. The seasonal timing and intensity of runoff events, the location and availability of major phosphorus sources, and measures taken to contain those sources and manage runoff all affect the delivery process.
Stream monitoring may be used to evaluate the effectiveness of conservation practices by tracking phosphorus loading. Loading describes the total mass of phosphorus delivered to a specific location in a stream over time. In our case, we characterize loading in pounds of phosphorus (calculated by multiplying in-stream concentrations by streamflow) delivered through Lake Mendota’s monitored stream tributaries in a given water year (Oct. 1 – Sep. 30).
LAKE MENDOTA:
BELLWEATHER FOR THE CHAIN
Perched at the top of the chain and receiving most of the watershed’s drainage, the condition of Lake Mendota is a good indicator for how the downstream lakes will be impacted. Lake Mendota is also the largest lake with the greatest number of monitored streams and the most complete long-term dataset. The lion’s share of phosphorus received by the lower lakes is through the outlets of the upper lakes as it cascades through the system.
Figure 4 shows the change in stream-monitored phosphorus loading to Lake Mendota since 2013. Total precipitation is also plotted in orange to distinguish between wet and dry years. In both 2021 and 2022, phosphorus loading to Lake Mendota significantly declined. This was largely due to recent drier weather after years of above-average precipitation, reducing the amount of runoff and phosphorus delivery.
Based on the most recent 10 years of phosphorus loading data, there is a 56% gap between the annual average load to Lake Mendota over this period and the goal of 32,600 pounds per year. Scientists estimate a doubling of summer days when the lakes are clear and free of algal blooms if this lower average loading goal can be achieved. However, this objective remains elusive due to the increasing volume of runoff and streamflow from a wetter climate that is bringing more phosphorus into the lakes.
“The good news is that if runoff and streamflow volumes had not changed, modeling indicates a significant decline in phosphorus loadings would have occurred over the last 30 years. This is due, in part, to increased adoption of conservation practices that have decreased the concentration of phosphorus in runoff,” said Matt Diebel of the U.S. Geological Survey and former chair of the Yahara CLEAN Compact’s scientific advisory committee. In other words, the long-term trend of wetter weather and increased runoff is counteracting the positive effects of these practices under their current rate of adoption.
Several in-lake metrics are used to assess overall lake health and track changes over time. Those metrics include water clarity, phosphorus concentration, presence of cyanobacteria (blue-green algae) blooms, and beach closures. Each is summarized below. Generally, most of the lakes fared relatively well in 2022. Lake Kegonsa, the shallowest and most downstream lake in the chain, was the exception with respect to median phosphorus concentration, nearshore clarity, and cyanobacteria bloom sightings.
Water clarity readings are taken by lowering a Secchi disk from the surface over the deepest point in each lake. The depth at which the disk can no longer be seen is known as its Secchi transparency. As shown in Figure 5, summer median clarity values in 2022 were indicative of “good” water quality conditions in lakes Monona, Wingra, and Kegonsa. Summer clarity was borderline “good” in Lake Mendota and “fair” in Lake Waubesa.
Because the amount of algal growth in the lakes is usually influenced by the availability of phosphorus as its main fuel source, clarity changes often mirror changes in phosphorus concentrations. In the case of Lake Wingra, the continuation of favorable water clarity may likely be attributed to a major carp-removal effort in March of 2008. The non-native carp stir up the lake bottom and uproot aquatic plants through their feeding behaviors.
In 2022, summer median phosphorus concentrations were indicative of “good” to “excellent” conditions for lakes Mendota, Monona and Wingra (Figure 6). The lakes lower in the chain did not fare as well, with Waubesa classified as “fair” and Kegonsa as “poor.” According to Richard Lathrop of the UW-Madison Center for Limnology, “Lake Kegonsa’s concentrations were very high with dissolved phosphorus elevated way above analytical detection. This means summer algal growth in the lake was not limited by how much phosphorus was available. In contrast, the upstream lakes, including shallow lakes Wingra and Waubesa, had undetectable levels of dissolved phosphorus as algae effectively utilized available supplies.”
Recent drought years continue to have a positive effect on in-lake phosphorus concentrations. Lake Mendota’s concentrations after fall turnover hit a record low in 2022, a consequence of less runoff and external phosphorus loading (Figure 7). Turnover occurs when deeper lakes cool to the point where the water column can completely mix, usually around early November. This seasonal phosphorus index is thought to offer a better estimate of Lake Mendota’s phosphorus status. During turnover, high phosphorus concentrations accumulating in the lake’s bottom waters are mixed throughout the lake.
Fall turnover phosphorus concentrations were also low in 1988 and 2012 following those extended droughts. “This is good evidence that Lake Mendota’s phosphorus status declines when external loads are low with benefits that should cascade down through the lower Yahara lakes,” said Lathrop. He says this shows the lakes can respond quickly and positively when phosphorus inputs are reduced. In addition, he points to 2008 and 2018-19 as high-loading years after which Lake Mendota’s phosphorus status quickly recovered. This reveals that internal (in-lake) loading does not continue to maintain the lake’s high phosphorus concentrations.
Clean Lakes Alliance trains and coordinates a network of volunteer monitors who also track water quality changes as part of its LakeForecast program. In 2022, monitors submitted 2,094 lake-condition reports. The bulk of these reports provide real-time information on the status of nearshore areas where most people interact with the water. Clarity, water temperature, and cyanobacteria bloom evidence are among the water quality parameters evaluated. The data complement center-of-the-lake measurements, painting a more complete picture of how conditions can vary over time and space.
Volunteer monitor reports indicated a relatively good year for the lakes for nearshore clarity and cyanobacteria bloom evidence, except for Lake Kegonsa that had an above-average number of bloom sightings (Figure 8). Lakes Mendota, Monona, and Waubesa had some of the lowest reports of strong cyanobacteria blooms since LakeForecast monitoring began in 2013. For the first time since 2014, Lake Mendota lasted the entire season without a single report of a strong cyanobacteria bloom. Lake Wingra had only one day of strong cyanobacteria presence reported in early July. In stark contrast to the other Yahara lakes, Lake Kegonsa volunteers reported strong blooms on 31% of all sample days (May-September).
Compared to 2021, all lakes except Kegonsa showed improvement in average nearshore water clarity and were representative of “good” conditions as defined by Clean Lakes Alliance (Table 1). Lakes Monona and Wingra reported particularly high average clarity that was greater than their respective long-term medians. Lake Kegonsa, despite increased cyanobacteria bloom sightings, reported similar average clarity to 2021 and only slightly less than the 2015-2022 median. The lake’s shallower depth and its low-elevation watershed position likely contribute to its lower nearshore clarity readings. Water clarity for most lakes generally decreases throughout the summer with a peak decline in August. Lakes Monona and Wingra deviated from this pattern by exhibiting relatively high clarity readings throughout the monitoring season (Figure 9).
Beach closures prompted by observed and measured water quality concerns are another useful indicator of general lake health. Clean Lakes Alliance looks at closure data provided by Public Health Madison & Dane County for 17 beaches (Figure 10). Covering four of the five Yahara lakes, these tested public beaches were selected due to the consistency of tracking data over the prior 10-year period. Results are reported as total closure days recorded for each season, roughly running from Memorial Day to Labor Day. For example, if two beaches on a given lake are closed for a total of five days each, 10 closure days would be reported for that lake.
Closures are most often the result of high cyanobacteria and/or E. coli bacteria levels, with closure rates strongly influenced by timing and frequency of testing. Most beaches are tested once per week and then daily for beaches with a closure in effect. Cyanobacteria blooms, which are generally a product of high lake fertility, can be dangerous due to their potential to release toxins that can harm people, pets, and wildlife. High E. coli bacteria concentrations, on the other hand, indicate the presence of human or animal fecal matter that often carries pathogens that can cause illness.
In 2022, there were 91 beach-closure days reported, which is below the long-term median. Closures were relatively split between cyanobacteria and E. coli as the causes. This follows a year with a record 267 closures, with most occurring on Lake Monona.
The path to recovery rarely follows a straight line and disconnects sometimes happen between celebrated action versus how and when the lakes might respond. There will be successes and setbacks, good times and bad, and progress that elicits both hope and disappointment. All in all, the lakes belong to a watershed community that cares, collaborates, and acts. We value the health of our lands and waters. We also possess the knowledge and motivation to be effective stewards. Only time will tell if we are headed in the right direction through our investments and actions – a reality that can often lead to frustration among the people working toward cleaner lakes.
A recent article from Adam Hinterthuer at the UW-Madison Center for Limnology addressed this frustration, responding to an exasperated resident who wrote in to say they were sick of all the studies with no better water quality.
Hinterthuer began his post by quoting Victor Hugo – “Science says the first word on everything and the last word on nothing.”
He then continued, “Yes, science can tell us about the current state of our lakes and explain how they got that way and offer suggestions for how we head in a different direction. But that’s where science stops. It rarely gets the final say. It’s up to society to take it from there. Policymakers, resource managers, business leaders, and (perhaps the biggest agent of change) concerned citizens, are the actors that then get involved. When it comes to informed decision making, science provides the info. Society makes the decision.”
The “last word” is up to us. While annual State of the Lakes findings may at times send mixed messages, significant inroads are being made by many people and groups working for cleaner lakes. The guidance and tools are there, and we as stakeholders are called upon to play a positive role and leverage what is already working. If that happens, the days of consistently clear water, open and safe beaches, and a thriving lake community will certainly lie ahead and not behind us.
The Renew the Blue plan gives us hope that this is possible. As pointed out in Chapter 2 of that plan (State of the Science), “Even gradual change may produce noticeable improvements in water quality before the [phosphorus loading] target is met.” A welcome conclusion in a world full of uncertainty.
Date: Wednesday, May 3rd, 2023
Time: 7 – 8 a.m. coffee and conversation, 8 – 9:30 a.m. breakfast and program
Location: Monona Terrace Community and Convention Center (1 John Nolen Dr., Madison)
Please join us for our Clean Lakes Community Breakfast on Wednesday, May 3rd, 2023! We will continue the tradition of bringing together our watershed’s premier scientists, business and organizational leaders, heads of government, and officials from the Ho-Chunk Nation to learn more about the lakes (originally known as Teejop) and new opportunities for continued collaboration and progress.
Clean Lakes Alliance and its fellow Yahara CLEAN Compact members will highlight the latest science and Renew the Blue stakeholder guidance that will direct future cleanup actions.
Samantha Skenandore is a Federal Indian and Tribal Law-experienced attorney for Quarles, and an enrolled member of the Ho-Chunk Nation. She previously served as an elected Associate Justice for the Ho-Chunk Nation Supreme Court. As a rights-of-nature proponent, she supports advocating for laws that protect land and water.
Presented by: Foley and Lardner LLP
Major sponsors: Alliant Energy, CG Schmidt, Lands’ End, Hovde Properties, Johnson Financial Group, Madison Gas and Electric, UW Health, WKOW 27 News
