The goal 10 years ago — set by community leaders and scientists — was to cut by half the amount of phosphorus that washes into Madison’s lakes. That way, thick weeds and soupy green muck wouldn’t foul lakes Mendota, Monona, Waubesa, Kegonsa and Wingra every summer.
How are we doing toward that goal?
Pretty good, according to the latest State of the Lakes Report, published by the Clean Lakes Alliance. But progress must accelerate because of heavier rain and the development of farmland, which are offsetting progress.
Public Health urges swimmers to check conditions before entering the water at all beaches.
Efforts over the last decade to protect our lakes from phosphorus pollution that feeds algae and bacteria have prevented some 20,000 pounds of phosphorus from reaching the Yahara chain of lakes each year.
Advocates for clean lakes have planted buffers along streams leading to the lakes to slow erosion and protect them from phosphorus-laden runoff during heavy rainfalls. Local communities have built basins to collect stormwater. Urban residents have tried to keep leaves out of the streets to prevent them from washing away.
Most important, farmers in the Yahara River watershed continue to adopt innovative ways of keeping phosphorus-rich manure and soil from washing off their fields. They’ve planted cover crops, contoured fields and injected manure into the soil, rather than spreading it on top.
The result is that Madison and Dane County are getting close to halfway to the goal of keeping an estimated 46,200 pounds of phosphorus out of local lakes. The goal is important because just 1 pound of phosphorus can produce 500 pounds of algae. And too much algae contributes to smelly green slime ruining our lakeshores and closing beaches during summer.
The pandemic limited efforts to protect our lakes last year. Now that COVID-19 is in decline, renewed attention must return to our waterways, which define our city and shape its scenic Isthmus and Downtown. Our lakes are a big part of what makes living and visiting here so enjoyable.
The clarity of Madison’s lakes was “good” during 2020, while phosphorus concentration was “fair,” according to the latest lakes report. The best news is that scientific monitoring of the tributaries leading to our lakes shows the concentration of phosphorus in the water has decreased by 36% over the last two decades, according to the Dane County Land and Water Resources Department.
But that improvement has been offset by heavier and more frequent rains caused by climate change. Building homes on farmland also has created more hard surfaces that water easily runs off, rather than being absorbed into the ground. About 11,000 acres of watershed in Dane County were developed from 2000 to 2015.
Denser development in urban areas will help. So will more effective buffers around key waterways to protect against downpours. City residents can do their part by composting, building rain gardens or adding a rain barrel to downspouts to hold more water at bay.
Local governments in cooperation with farmers, nonprofits and volunteers play a big role. For example, Dane County purchased and is restoring a 160-acre addition to Pheasant Branch Conservancy, northwest of Lake Mendota. Once completed, this project is expected to stop 5 million gallons of runoff — and 550 pounds of phosphorus — from reaching the shoreline.
We all must do our part in protecting the lakes. Keep going, Madison. These precious resources deserve stepped-up attention and care.