Here’s one way to fix Lake Erie’s toxic algae

This summer another toxic algal bloom descended on Lake Erie, harming businesses and closing beaches. This year’s bloom follows a 2014 bloom that poisoned drinking water for more than 400,000 people around Toledo.

Efforts to curb the problem rightfully focus on the need to reduce farm runoff — the No. 1 cause of harmful algal blooms in Lake Erie. Rain and snowmelt wash excess fertilizer and manure off fields and into local streams and rivers that, ultimately, empty into Lake Erie. The excess nutrients feed the explosive growth of algae that mar beaches, impact fish and wildlife and hurt tourism. When that algae dies and decomposes, it creates dead zones devoid of oxygen — forcing aquatic organisms to move to better habitat or perish. This has hurt charter boat businesses and recreational fishing.

To be sure, some farmers are taking steps to reduce their impact downstream. Nevertheless, farm runoff continues to be a problem for communities in Ohio and across the United States. This year’s dead zone in the Gulf of Mexico was the largest on record. Harmful algal blooms continue to plague Chesapeake Bay and inland lakes and waters across the country.

State and federal public officials recognize the problem — and are starting to act. Michigan and Ohio joined Ontario to agree to cut phosphorus, the main driver of algae growth, by 40 percent by 2025. The federal government has started targeting farm conservation investments in priority areas like the Great Lakes region to reduce runoff.

These are all good steps. But more needs to be done.

One federal policy, in particular, deserves scrutiny: the ethanol mandate.

Formally known as the Renewable Fuel Standard, the mandate requires about 17 billion gallons of plant-derived fuels be blended into gas destined for our vehicles. Most is corn ethanol. Today more than 40 percent of our nation’s corn ends up in our gas tanks.

Producing that much corn has had dramatic impacts on the natural landscape. Since passage of the Renewable Fuel Standard nearly 10 years ago, more than 7 million acres of habitat have been plowed under and converted into crops — mostly corn — to satisfy the mandate. That staggering loss of habitat threatens species like the monarch butterfly, ground-nesting birds, bees, ducks and other species.

The massive land conversation also has the potential to exacerbate runoff pollution. At a time when the Great Lakes and other U.S. waters are experiencing record-setting algal blooms and dead zones, we need Congress to protect our water resources. The mandate has also driven up land prices for farmers and forced many to stop farming other crops, contributing to challenging economies for our farmers.

Congress can start by reforming the Standard. There are several common-sense solutions.

First, Congress can decrease the reliance on corn ethanol and encourage more sustainable fuels — being careful to avoid cultivating noxious or invasive species. Second, Congress needs to enforce provisions already in the law to prevent conversion of habitat to cropland. Third, Congress needs to invest in the restoration of wildlife habitats that have borne the brunt of damage.

Collin O’Mara is president and chief executive officer of the National Wildlife Federation.