Feature Article: From the Lake to the Lab: Water Quality Monitoring in the Yahara Watershed

by Garrett Hopkins, Rock River Coalition


Couples in kayaks. Families on beaches. Students in sunburst chairs on the Terrace. Lake Mendota is one of the most valuable social and recreational attractions in southwestern Wisconsin. It’s also the largest of the five lakes in the Yahara Watershed, and the focal point of the 30-plus-year-old Yahara Watershed Water-Quality Monitoring Project led by the U.S. Geological Survey (USGS).


The 384-square-mile watershed is home to about 370,000 people and contains 170,000 acres of some of the most productive farmland in the country. And while this condensed combination of agriculture and urbanization is a testament to the fertile soil and exquisite livability of the area, it’s also the cause of one of the biggest ecological issues facing the region: water pollution.


During significant water runoff events caused by heavy precipitation or snowmelt, pollutants wash from the landscape into local water sources. Runoff from farmland carries nutrients like phosphorus to nearby waterways. Throughout the year water that comes from developed landscapes, called stormwater, washes lawn chemicals, gasoline, road salt and oil over rooftops, driveways and roads into storm drains that lead to lakes and rivers. In autumn, stormwater also washes leaves, which carry phosphorus, into storm drains.


Phosphorus is an important nutrient for farmers since it’s essential for plant growth, but it’s extremely problematic when it gets into a body of water. It promotes blooms of algae that absorb oxygen and block sunlight, harming or killing underwater biodiversity, and certain types of algae can be toxic to humans and animals that ingest it. All of the lakes and rivers in the watershed have suffered increasingly high phosphorus loads for decades.


The severity of a runoff event is dictated by the intensity of the corresponding precipitation, and the amount of heavy precipitation events has greatly increased since the 1980s – a destructive effect of climate change. In response, the Wisconsin DNR and USGS formed the Yahara Watershed Water-Quality Monitoring Project in the late 80s.


“The purpose of the project is to have an accurate long-term record of what happens here,” says Todd Stuntebeck, Project Chief. “Having 30-plus years of data also lets us say, ‘Hey, the [conservation practices] we’ve implemented in the watershed to improve water quality are working. Or not, if they’re not.’” Conservation practices include various agricultural methods, autumn leaf removal operations, rain gardens, rain barrels, detention ponds and more.


While these conservation practices are growing in notoriety and popularity, the water-quality monitoring process is an unsung component of the operation. Thankfully, people like Stuntebeck have dedicated their careers to it. According to him, one of most important parts of the process is knowing when to take samples, and his team is most active during heavy runoff events. They use an arsenal of nearly a dozen automatic, 24-bottle samplers.


“We go out when there is increased streamflow,” he says. “We have sites that are telemetered, so we know what’s happening at all times. When a runoff event is over, we’ll go pick up the racks of samples and bring them back to the lab to figure out which ones are the best representation of water quality data through the event.” For a large event, they will submit up to twelve samples to an analytical lab and aim to submit around one hundred per year.


Knowing where to collect samples from is another crucial part of the process, and the USGS primarily samples tributaries of Lake Mendota. “Lake Mendota in particular is so important to the overall health of the watershed because it’s the largest and most upstream lake in a series of five lakes. Any chemicals you have in the lake have the potential to be transported to downstream lakes through the Yahara River System.”


Although there has been more community outreach and funding dedicated to conservation efforts in recent history, water quality hasn’t changed much across the watershed. This doesn’t mean these efforts are failing but is instead a reflection of increased agriculture, urbanization and significant runoff events. “Everything we’ve done to address the issue is basically keeping things level. If we hadn’t done anything, I think it’d be pretty ugly out there right now. What we’re doing is keeping us on the treadmill.”


For now, staying on the treadmill is an accomplishment. For the future, some of the brightest minds in climate research and water quality protection are on the case. Specifically, in 2022, a group of community leaders, experts and stakeholders gathered to create an action plan for the Madison area lakes. The 188-page plan, called Renew the Blue: A Community Guide for Cleaner Lakes & Beaches in the Yahara Watershed, was published on May 18, 2022. The plan is largely informed by the data collected by the USGS..


There’s a simple reason Lake Mendota is such a popular destination: people love being near water. Water is communal, water is educational and water is inspirational. Water is also a fragile resource that must be preserved. While the work of researchers like Todd Stuntebeck often goes unheralded, their service to the community is immeasurable. Rock River Coalition is grateful for the opportunity to acknowledge this important project, and we’d like to offer a heartfelt thank-you to all who dedicate their time and expertise to protecting the Yahara Watershed.