U.S. knows how to keep Lake Erie from dying all over again

More than half a million people in the city and suburbs of Toledo, Ohio, got a break Monday: They were told that their tap water was safe to drink again.

That was two days after residents were warned that their water posed a health risk because of toxins related to an algal bloom in Lake Erie, the source of the city's water.

Isn't it a little unnerving that one day you can't use your tap water to brush your teeth or wash dishes, let alone drink, because officials say it might cause damage to your liver and nervous system, and then, the next day, the problem has disappeared?

Unless the Clean Water Act and other environmental regulations are updated and steps are taken to mitigate the causes of algal blooms in the Great Lakes as well as the Gulf of Mexico, many Americans will rightly worry about the safety of their drinking water, and more bans such as the one in Toledo are likely. The key is reducing the amount of phosphorus flowing into rivers and lakes.

The science is well understood: Pollutants, mainly from agricultural runoff and, to a lesser extent, sewage-treatment plants, stimulate growth of algae during the warm summer months. The algae in this case — a blue-green variety called Microcystis — release what are known as cyanotoxins, which can be difficult to detect and can't always be filtered out by municipal water-treatment systems.

The algae don't cause problems just for people. When they die, they fall to the lake bottom, where they decompose. This uses up most of the oxygen in the water, leading to fish kills and so-called dead zones during warm weather.

The U.S. government should remember how expensive it is to wait too long to save its water from such degradation. Lake Erie, which was known as "North America's Dead Sea" in the late 1960s, was saved mainly by the Clean Water Act of 1972, which required sewage-treatment plants and industry to limit how much pollution they discharged into U.S. streams and rivers. It was an enormous undertaking, with federal and state governments spending more than $60 billion nationwide to improve treatment facilities. This cut a major source of phosphorus, as did changes to household-detergent formulations that relied on phosphates.

The International Joint Commission, an effort by the United States and Canada to monitor and improve water quality in the Great Lakes, has called for an immediate reduction in the amount of phosphorus flowing into the lakes. Among its recommendations is that farmers reduce the amount of fertilizer they use and when they use it. For example, many farmers apply manure-based fertilizer to frozen fields, where some of it dissolves and runs off with the spring thaw. This practice should be banned.

Farmers also need to create buffer zones — unplanted areas next to fields — that slow runoff and help to retain fertilizer. The use of cover crops such as hay and rye, planted in the off season, may also prevent nutrient loss: These absorb nutrients while growing, then release them back into the soil when they die, becoming available for commercial crops such as corn and soybeans.

Farmers already try to limit fertilizer losses, which may be as low as 2 percent. It's a costly input, and what gets washed away in the rain can't be used to grow crops.

Technology can help. Infrared sensors can detect the ideal time to apply fertilizer, and GPS can help determine what parts of a field need how much fertilizer. Yes, technology has its limits, and today's researchers don't necessarily agree on what approaches work best.

What's clear is that today's regulations aren't up to the job of safeguarding the nation's drinking-water supply. Rules that mandate stricter rules for fertilizer application should be adopted. Lawmakers also should tie the availability of federal subsidies to farms, such as crop insurance, to farm-management practices that reduce runoff. In the meantime, cities like Toledo will be stuck paying the bill as they spend more money to monitor, test and filter water.