The Chesapeake Bay isn’t the only major waterway that needs to be on a nutrient diet to trim down excess algae production. An international panel last month called for implementing a phosphorus diet for Lake Erie that would slash the amount of the nutrient reaching the lake by half over the next nine years.

Water quality problems for Lake Erie aren’t new. The shallowest of the five Great Lakes, it has long been most susceptible to the impacts of pollution which pours in from rust belt cities along its shores and farmland in its watershed.

One of its tributaries, the Cuyahoga River, famously caught on fire in 1969 (one of a dozen times it had done so over the course of a century), which led Time magazine to describe it as a river that “oozes rather than flows.”

The sorry state of the Cuyahoga helped lead to the Clean Water Act a few years later, and in the following decades water quality in Lake Erie — once proclaimed as “dead” — dramatically improved as flows of toxins and other pollutants were stemmed. States reduced sewage flows and banned the use of phosphate detergents that caused large algal blooms on the lake.

By the 1980s, Lake Erie’s  recovery was a globally recognized success.

But water quality in the lake has been worsening since about 2000. The  lake has been plagued with algae blooms, oxygen-starved water, and fish kills. 

Scientists blame excess phosphorus. (Unlike salt water, where nitrogen is the nutrient the drives algae production, phosphorus is typically the most important nutrient in fresh water systems.)

The blooms decades earlier had been successfully managed by controlling point source discharges, but the new blooms are largely caused by increased phosphorus runoff from farms and urban lands, according to a report by the International Joint Commission, an independent panel of experts established by a treaty between Canada and the United States in 1909.

According to the report released last month, “A Balanced Diet for Lake Erie,” heavy spring rains in 2011 flushed a large amount of phosphorus into the western portion of the lake, followed by a period of warm weather, resulting in an algae bloom measuring 1,930 square miles — three times bigger than any bloom previously observed.

Some of the algae in recent years have been toxic, creating threats to fish, wildlife and humans who want to swim, fish or water ski. Other types are particularly smelly, and all degrade  water quality and contribute to a summertime oxygen-starved dead zone in deep areas of the lake that threatens recreationally important fish.

The United States and Canada have goals to reduce phosphorus by 2018, but the report said those reductions are too modest to restore the lake’s water quality and said that actions need to be phased in more rapidly. It called for a 46 percent reduction in the amount of phosphorus reaching the lake from its western and central basins — those with the greatest impact on water quality — during the spring. It called for even steeper reduction on an annual basis.

It called for the reductions to be phased in over nine years, to be completed by 2022, with interim three-year reduction targets established.

It also calls for Michigan and Ohio to list western Lake Erie as impaired and then develop a Total Maximum Daily Load, under the oversight of the federal Environmental Protection Agency, to control phosphorus. That TMDL would also affect the “upstream” state of Indiana which doesn’t touch Lake Erie, but has farmland that drains into it.

The report called for states around the lake, along with the Canadian province of Ontario, to dramatically ramp up voluntary programs, as well as regulatory programs where needed, to control agricultural runoff into the lake.

Among its recommendations was that the United States and Canadian governments link the cost and availability of crop insurance premiums to farm conservation plans and implementation of nutrient management plans.

The report also called for a 10 percent increase in coastal wetlands around the lake by 2030.

It called for regular inspections of septic tanks and for improved stormwater controls, including increased use of grass filter strips and rain gardens. And   it called for Ontario, Ohio and Pennsylvania to ban phosphorus in most lawn fertilizers — they are already banned in Michigan.

Exactly what happens with the recommendations is not clear. Although the commission was established to make recommendations about important issues affecting the Great Lakes, its advice is not binding.

Interestingly, the attorneys general of two states that would be affected —Michigan and Indiana — recently signed onto a friend of the court brief challenging the EPA’s authority to establish the Chesapeake Bay pollution diet.