During the first four days of August, the western basin of Lake Erie made national news. A harmful algal bloom, which scientists call an HAB, threatened the water supply near Toledo, Ohio. Wind and water currents pushed a bloom of blue-green algae (cyanobacteria) to the intake of the city's water plant. Toxins produced by this algal bloom -- microcystin was of greatest concern --made the water undrinkable for several days.
Aquatic biologist Jeff Reutter, director of Ohio Sea Grant and Stone Laboratory at Ohio State University, said Pennsylvania waters would be relatively safe from the toxins, and properly filleted fish caught off Erie County were safe for consumption
What causes HABs?
Warm water (above 60 degrees) and high concentrations of phosphorus trigger blue-green algae blooms.
Why did this recent HAB occur in western Lake Erie?
The western basin of Lake Erie (west of Sandusky, Ohio) is shallow (average depth 24 feet), so its waters are warmer than those to the east. Combine warm water with high concentrations of phosphorus from fertilizer run-off flowing into the lake from the Maumee River, and HABs are predictable.
The Maumee watershed drains 4.2 million acres of farmland, so its runoff is rich in phosphorus.
The central basin of Lake Erie, from Sandusky to Erie, Pa., has an average depth of 60 feet, and the eastern basin located east of Erie is even deeper with a maximum depth of 210 feet.
Because there's more water in the central and eastern basins, it stays cooler and HABs are less frequent, less severe, shorter lived, and smaller in size than blooms in the western basin.
The other four Great Lakes are larger and deeper (more than 750 feet deep), and their watersheds are primarily forest ecosystems, so there is much less agricultural run-off. That's why HABs tend to occur in western Lake Erie.
Will conditions that caused the recent HAB move east to the Erie area?
That's unlikely because of the greater volume of cooler water in the central and eastern basins, and because there is less agricultural run-off there.
Are Lake Erie fish safe to eat?
The Ohio Department of Natural Resources reports that as long as fish fillets are properly cleaned and rinsed, they are safe to eat.
Biologist, author and broadcaster Scott Shalaway can be heard 8-10 a.m. Saturdays on 1370 WVLY-AM (Wheeling) and online at www.wvly.net. He can be reached at www.drshalaway.com, firstname.lastname@example.org and 2222 Fish Ridge Road, Cameron, W.Va., 26033.