Map: Not All Phosphorus Is the Same

Give Water a Voice

Your support helps inform the world’s most important decisions about water and all that it touches.

One-time Monthly Annually

One-time

$20

$45

$245

Other Donation amount

$

Monthly

$9

$15

$30

Other Donation amount per month

$

Annually

$100

$500

$1,000

Other Donation amount per year

$

Your contribution is appreciated.

Donate Now

A breakdown of the different types of phosphorous in Ohio’s Maumee and Sandusky rivers that have led to algal blooms in Lake Erie since the 1970s.

Phosphorus — a nutrient found in fertilizers, sewage, soaps, and detergents — feeds the large blooms of toxic algae that are plaguing Lake Erie. While phosphorus levels overall have declined in Lake Erie and its tributaries since the 1970s, the amount of dissolved reactive phosphorus (DRP), a form that is more easily used by algae, has grown since the 1990s. Water quality data sets show a steep increase in the percentage of DRP washing into Ohio’s Maumee River watershed, which is Lake Erie’s largest tributary and a primary contributor of the phosphorus that drives the lake’s algal blooms.

Scientists at universities throughout the Great Lakes region believe that changing agricultural practices and climate change are behind the recent increases. Together, these trends are creating larger algal blooms. Researchers are now exploring which farming practices could reduce dissolved phosphorus runoff, and stakeholders from conservationists to municipal water managers are urging governments to take legal action to address the problem.