Despite being, arguably, the most important natural resource in the Midwest, the Great Lakes remain extremely vulnerable to natural and man-made pollution. Though algae blooms are a naturally occurring phenomenon, recent blooms in Lake Erie are so extreme that people in parts of Canada and Ohio have been instructed not to use their water for drinking or recreational purposes.
Lyman Welch, Water Quality Director of the Alliance of the Great Lakes, explains that though the blooms are naturally occurring, the extremely high levels and resulting negative implications of recent blooms are both human induced and reversible.
"We've had a history in the Great Lakes of algae, which grows naturally," Welch explains. "But when we have excessive amounts of nutrients in the water, mainly from agricultural runoff, it feeds the algae, and we'll get a large algae bloom."
In addition to affecting wildlife and water quality, the algae washes up and accumulates on shores, detracting from the natural beauty and keeping people away from certain destinations.
Lake Erie is the shallowest of the five Great Lakes, reaching depths no greater than 20 feet in many areas. The shallow basin allows water temperatures to fluctuate more easily and quickly. As the warmest of all the Great Lakes, Lake Erie is particularly susceptible to the formation of the blooms.
"The short depths combined with the warmer waters and introductions of invasive species like zebra mussels have contributed to larger algae blooms in recent years," Welch explains. "The main element that causes algae is the nutrient input, which we have control over. Excess nutrients are coming into the lake from several states and are the largest source contributing to this problem, with phosphorous as the main culprit."
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