Our Greatest Threat
THE CHALLENGE:
PHOSPHORUS POLLUTION IN GREEN LAKE
Protecting Wisconsin’s deepest natural lake for future generations.
Green Lake was listed as impaired by the Wisconsin DNR in 2014. Each year, 10 tons of phosphorus enter the lake, where it lingers for decades—fueling algal blooms, depleting oxygen, and straining aquatic life. Because phosphorus accumulates over time, a 60% reduction is needed to restore water quality and prevent long-term damage.
EXPLORE THE CHALLENGE
Green Lake is at a turning point. Use the links below to dive into the story and discover how you can make a difference.
The ripple effects of phosphorus on life, property, and our local economy.
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Explore the GLA’s decade of research & collaboration that brought us to a place for an actionable solution.
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WHY THIS MATTERS TO YOU
Phosphorus pollution threatens more than just water clarity. Unchecked, it fuels harmful algal blooms, chokes oxygen levels, and disrupts fish habitat. The ripple effects touch every part of our lives:
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Recreational Quality
Excess phosphorus fuels algae growth, leading to murky, unpleasant waters that interfere with swimming, boating, and fishing.
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Health & Safety
Some algae blooms release toxins that pose serious health risks to people and pets.
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Property Values
Clean, clear water helps maintain and boost shoreline property values, while degraded water quality can lead to significant losses.
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Local Economy & Tourism
A healthy lake supports tourism and recreation-based businesses, which are vital to the region’s economy.
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Community Pride & Quality of Life
Green Lake is central to the identity and enjoyment of this community—protecting it protects what makes this place special.
KEY INTERVENTION POINTS
Not all sources of phosphorous contribute equally. Research shows that two main inlets are responsible for the majority of controllable phosphorus that enters Green Lake:
WHAT WE CAN CONTROL
Some phosphorus sources are within our power to manage through conservation, behavior change, and education. These are called controllable sources. Others—like rainfall and atmospheric deposition—are uncontrollable but can be mitigated by buffering the lake’s resilience.
