Yahara Portal

Explore the legacy and future of the Yahara Lakes and Watershed

Water Quality

Water quality in the Yahara Watershed - a brief history

Before European settlement, the Yahara lakes were a gathering place for the many tribes that lived and traded in Wisconsin following the retreat of the glaciers about 12,000 years ago. The sparkling waters of the lakes and the verdant marshes supported bountiful fish, waterfowl and other wildlife, and the lakes provided useful transportation routes.  European explorers and settlers recognized these same advantages when they came to the region.  After the War of 1812 and the Black Hawk wars, western expansion into Wisconsin exploded.

In what would become Madison, early settlers in the 1830s described Mendota’s waters as clear enough to see to see 30 to 40 feet to the bottom.  When statehood came in 1843, Madison had grown to 300 people. By 1856, the new Capital city’s population had reached 9,000 and showed no signs of slowing down.  With the settlers came the plow, and with cultivated soil came erosion and silt flowing into streams and lakes. Statehood also birthed the University of Wisconsin, and by 1870, Professor E. A. Birge was studying the lakes. Only five years later, the limnology department documented what might have been the first noxious algae bloom in Lake Mendota.

European immigrants were surprised not to find carp in America. The common carp was widely cultivated in ponds as a food source throughout Europe, and in response to public demand, entrepreneurs and eventually the U.S. Fish and Fisheries Commission introduced the common carp to American waters, including Madison lakes in 1890.  However, carp muddy the waters in which they live, and they have had been doing so for more than a century.

As farms expanded, local gunpowder producers turned their chemical know-how into producing nutrient-rich fertilizer, which flowed, along with eroded top soils, into waterways.  The city of Madison and surrounding towns kept growing. By 1940, Madison’s population had grown to 67,000 and after World War II, suburban growth also expanded rapidly.

The farms and the growing urban and suburban areas released sediments—which cloud and warm the water—along with nutrients from fertilizer and sewage. This was the perfect recipe for growing algae with warm summer sunlight.  Lakes that were once clear exploded into green soupy conditions thanks to the proliferation of pumped up algae colonies.

Today we take sewage treatment systems for granted, but until 1971, sewage ran into the lakes and rivers. Modern sewage treatment helped clean up local waters, but the urbanizing landscape over the last several decades has meant less land for agriculture in the watershed, and dairy operations and cows have been concentrated on less acreage, and thus, so has manure. Runoff from both agricultural lands and cities and suburbs has continued to fertilize the lakes with an overload of phosphorus and nitrogen, which causes the algae blooms, scums, and sometimes even dangerous bacteria levels that degrade our water quality and enjoyment of the lakes.

Numerous investments in research, planning and agency coordination in the last 15 years have led to a clear understanding of the problem and the most practical, promising and effective solutions. Today, we know the actions that will lead to cleaner, healthier lakes and waters, and our communities are pulling together to rehabilitate our treasured lakes.