With spring just about here, people will soon start wondering how bad western Lake Erie’s algae will be this year.

Many forget the 2015 bloom, while relatively low in toxin, was the largest in terms of biomass since a satellite began sending daily images of the lake in 2002 for the National Oceanic and Atmospheric Administration to track algae.

Last summer’s bloom covered more of western and central Lake Erie than the previous record set in 2011.

A few thoughts about the issue emerged at the Lake Erie Waterkeeper’s annual conference Friday, attended by about 100 people at the W.W. Knight Nature Preserve in Perrysburg:

First, don’t get too wrapped up in what this year’s El Nino-influenced winter meant.

Jeff Reutter, Ohio Sea Grant and Ohio State University Stone Laboratory special adviser, said winter temperatures are overrated as an indication of algal growth because of Lake Erie’s shallowness. 

The water temperature changes quickly.

The coldest May on record for western Lake Erie water was in 2011, yet a then-record algal bloom occurred. Scientists have learned June is the real make-or-break month for algal growth: A hot June will grow a lot of algae while a cool one won’t.

Second, conventional wisdom about agriculture’s impact is changing.

Critics of big agriculture suspect a stronger link between water quality and megafarms classified as confined animal feeding operations with many more chickens, hogs, and other animals being brought into the region.

More animals means more manure headaches.

“When you add more and more manure to a watershed that’s already saturated, that’s a problem,” Sandy Bihn, Lake Erie Waterkeeper executive director, said.

There are 146 confined animal feeding operations in the western Lake Erie basin — 57 in Ohio, 75 in Indiana, and 14 in Michigan, according to Pam Taylor of Environmentally Concerned Citizens of South Central Michigan.

Those in the basin’s southeast Michigan corner alone produce the waste equivalent of the city of Boston, she said.

“The connection between liquid manure and drain tiles is pretty strong,” Ms. Taylor said.

Manure is one of many sources of what’s known as dissolved reactive phosphorus, the most troublesome kind of fertilizer because 100 percent of it dissolves immediately into the water and helps algae grow.

Particulate phosphorus, often in commercial fertilizers, is only 20 percent bio-available, according to Laura Johnson, director of Heidelberg University’s National Center for Water Quality Research.

Heidelberg, which has the Great Lakes region’s largest set of runoff data, found last summer’s total phosphorus fairly typical, but also learned the concentration of dissolved reactive phosphorus was off the charts, Ms. Johnson said. 

She said that could help explain the massive algae bloom.

But that’s not all. Ongoing Ohio State University research presented at the conference suggests as much as 80 percent of the runoff is entering area tributaries via underground drainage tiles, much more than previously thought.

Another ongoing study, presented by Bill Myers of the Lucas County Farm Bureau, suggests that 20 years of successful efforts by the U.S. Environmental Protection Agency to reduce sulfur dioxide emissions — the pollutant that results in acid rain — may have had the unintended consequence of changing soil in a way that allows more dissolved reactive phosphorus to pass through it.

“It was like a light bulb went off,” Mr. Myers said. “We need to change the amount of nutrients it takes to grow a crop if this change truly has happened.”

That point was made earlier in the day by Mr. Reutter, who represented Ohio on a U.S.-Canada pledge to reduce nutrient runoff by 40 percent. Mr. Reutter said that goal needs to be tweaked every five years.

“A lot of our strategies are based on particulate phosphorus, and dissolved reactive phosphorus is four times more important,” Mr. Reutter said.

Research shows 10 percent of northwest Ohio’s rainfall causes 65 percent of the runoff, according to Ron Wyss, a Hardin County farmer and secretary of the Lake Erie Improvement Association. 

His point: Major storms make a big difference.

Even though Toledo’s algae-based water crisis from 2014 differs from the ongoing lead-based water crisis in Flint, Mich., event organizer Sandy Bihn and several speakers drew parallels in terms of accountability.

“I’ll be very blunt about it. I think one of the problems is we have a very ineffective U.S. EPA [Region 5, based in Chicago],” Ms. Bihn said.

Contact Tom Henry at: thenry@theblade.com, 419-724-6079, or via Twitter @ecowriterohio.

First Published March 19, 2016, 4:00 a.m.