Federal and state agencies must find ways to control fertilizer runoff feeding Gulf of Mexico’s dead zone.

Aug. 4, 2008, 11:01PM

As Tropical Storm Eduard moves toward the Upper Texas coast, it is providing a little-noticed service. In churning the normally languid summertime coastal waters, it is curbing the spread of an 8,000-square-mile dead zone.
The zone, first detected in the 1970s, is created when the outflow of the Mississippi River dumps nitrogen and phosphates from crop fertilizer runoff and human effluent into the Gulf of Mexico, sparking intense blooms of algae.
As the algae decompose and sink into the depths, oxygen is absorbed from the water, creating an environment where fish, crabs and shrimp cannot survive. The phenomenon known as hypoxia typically occurs during the summer months, and dissipates with the arrival of cooler weather. This year’s dead zone is tied for the second-largest on record, topped only by an 8,500-square-mile monster in 2002.

The Gulf Coast is not the only area plagued by hypoxia. On the East Coast, the Chesapeake Bay and Atlantic coastal waters have suffered episodes of algae blooms that create toxic red tides costing the shellfish industry tens of millions of dollars.

Scientists had expected a record dead zone in the Gulf this year because of the flooding along the upper Mississippi watershed, which boosted fertilizer runoff by an estimated 35 percent to 40 percent. The recent boost in corn production to feed the growing ethanol industry also exacerbated the situation. Corn cultivation requires more nitrogen-based fertilizer, creating higher pollution levels.

Tropical systems help to counter the spread of the dead zone along the Louisiana and Texas coasts. Nancy Rabalais, who leads the Louisiana Universities Marine Consortium and conducts an annual measurement of the zone, credits last month’s Hurricane Dolly with keeping the dead zone from reaching record levels this year. Storm waves provide turbulence that mixes aerated surface waters with the deeper, oxygen-depleted zones.

Rather than depend on storms to mitigate the growing environmental damage, government must take on the problem at its source, the farmlands bleeding fertilizer and riverside cities leaking untreated wastewater into the Mississippi. Earlier this summer, a task force of federal and state officials released an action plan to target upstream pollution sources and reduce their flow into the Gulf.

Sens. Olympia Snowe, R-Maine, and Bill Nelson, D-Fla., are sponsoring the Harmful Algal Bloom and Hypoxia Amendments Act of 2008.

The Gulf of Mexico provides a livelihood for our commercial fisherman, sport for anglers and seafood bounty for dinner tables. Preventing the growth of the dead zone is an urgent priority that deserves the full attention of both federal and state environmental regulators.

Copyright 2008 Houston Chronicle