Cyanobacteria (blue-green algae) thrive when phosphorus and nitrogen from agricultural runoff combine with warmer water temperatures from climate change. Lake Erie's western basin receives phosphorus from 3 million acres of Ohio and Indiana farmland.
Blooms produce microcystin — a liver toxin — and cylindrospermopsin, which causes kidney damage. Toledo, Ohio declared a water emergency in 2014. In 2026, 12 communities along Lake Erie issued do-not-drink orders lasting over 30 days.
Great Lakes surface temperatures rose 3.4°F since 1980 — faster than global ocean averages. Warmer water and longer ice-free seasons extend bloom duration. By 2050, blooms are projected to occur 3 weeks earlier and last 2 weeks longer unless action is taken.
$7 Billion Threatened
The Great Lakes fishing industry, recreational tourism, and real estate market depend on clean water. Algae blooms close beaches, kill fish, and deter tourism — costing Great Lakes communities an estimated $7B annually in lost economic activity.
The US-Canada Great Lakes Water Quality Agreement targets a 40% phosphorus reduction by 2030. Ohio and Indiana launched voluntary ag programs — but compliance rates remain under 30%. The 2026 CLEAN Act proposes mandatory nutrient runoff limits for farm operations over 500 acres.
Our Great Lakes Need Us
8 states, 2 countries, 40 million people. The Great Lakes hold 21% of the world's surface freshwater. Protecting them from toxic algae requires policy, agriculture reform, and climate action — starting now.