Weather plays big role in Lake Erie ‘dead zones’

TRAVERSE CITY, Michigan (AP) ― Reducing phosphorus levels in Lake Erie is a worthy goal but not necessarily a cure-all for one of the lake’s biggest environmental hazards: “dead zones” with oxygen levels so low that fish can’t survive, scientists said Tuesday.

Researchers with the Carnegie Institution for Science said Erie’s biggest dead zone on record formed in summer 2012. While phosphorus-laden fertilizer runoff from farms played a part, weather conditions including drought and low flows from tributary rivers and streams were even more influential, they said.

The findings suggest policymakers working on plans for combating the lake’s dead zones ― and its worsening problem of harmful algae blooms ― should consider meteorological trends as well as agricultural management practices, said environmental scientist Anna Michalak, who led the study. That’s especially the case as climate change brings more extreme weather, she said.

“It means we need to be careful in our assumptions about how management is going to affect” oxygen levels in the water, Michalak said. “Reducing nutrient input won’t always give you as much bang for the buck as you might assume.”

Although Erie is the shallowest of the five Great Lakes, with an average depth of just 19 meters, it produces more of the types of fish that people eat.