2022 State of the Lakes
2022 State of the Lakes
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.
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.
1. Weather and climate drivers
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.
2. Watershed phosphorus mass balance
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.”
3. Land conservation practices
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.
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.
4. Phosphorus delivery to the lakes
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).
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.
5. In-lake water quality responses
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.
Mid-lake clarity and phosphorus concentrations
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.
Nearshore clarity and cyanobacteria blooms
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.
Tale of two watersheds
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.
About the State of the Lakes
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 our lakes
Learn more about lakes Mendota, Monona, Wingra, Waubesa, and Kegonsa.
- 2021 State of the Lakes
- 2020 State of the Lakes Report
- 2019 State of the Lakes Report
- 2018 State of the Lakes Annual Report
- 2018 Progress and Challenges video – shown at the 2019 Community Breakfast “Join the Wave”
- 2017 State of the Lakes Annual Report
- 2016 State of the Lakes Annual Report
- 2015 State of the Lakes Annual Report
- 2014 State of the Lakes Annual Report
- 2013 State of the Lakes Annual Report
- 2012 Annual Report / 2012 State of the Lakes Report
- 2011 State of the Lakes Report