The Mississippi got a lot of help from the Clean Water Act, which this week is celebrating its 35th birthday. The Nixon-era law forced cities to beef up their sewage treatment plants, and factories to clean up their wastewater.
The biggest threats to the river are runoff from farm fields, which is loaded with nitrogen, phosphorus and other nutrients and sediment -- again mostly coming from farmland.
The nutrients are the main cause of the "dead zone" in the Gulf of Mexico. The sediments are filling in parts of the upper reaches of the river, and not reaching the wetlands in the south, where they're needed to protect the coast from hurricanes. The Minnesota-based McKnight Foundation sponsored the study, which was conducted by the National Research Council, a nonprofit that provides policy advice. The challenge for the Mississippi now is in some ways more complicated than the untreated sewage and industrial pollution that came before, says the report's lead author, David Dzombak, from Carnegie Mellon University.
It requires data. It requires modeling. It requires people thinking about it. It's a resource-intensive activity, and further, it brings into view some significant contributing sources, especially these non-point sources from rural areas, that are difficult to address legally and technically," he said.
The Clean Water Act does offer tools to address the problems, but the Environmental Protection Agency hasn't been using them, according to co-author Robin Craig, from Florida State University.
Specifically, the EPA has authority to coordinate state programs, which are currently uneven and inconsistent, according to Craig.
"These interstate provisions already exist, and are waiting in possible combination with water quality trading, with the EPA's watershed approach, which the EPA is trying to expand, waiting to be used to address these larger systemic ecosystem issues that could get us to fishable swimmable," she says.
The report says in addition to the EPA, the U.S. Department of Agriculture has tools to address the problem. It is possible to pinpoint those sources and deal with them, according to another study author, Otto Doering, from Purdue University.
"In any given watershed, it literally can be as little as 10% of the watershed that's providing 80-90% of the nutrients or sediments," he says.
He says a lot can be done with conservation programs. Those programs offer incentives to farmers to use best practices or set land aside to protect nearby streams. But those programs have been run more as a way to get cash into rural areas than as a tool to protect land and water, according to Doering.
"It's seen as an income entitlement to some extent historically. That has to stop. We've got to target these programs for cost-effectiveness."
That's even more important as farmers respond to higher demand for corn for ethanol, he says.
There is a model the report's authors would like to follow. It's the multi-jurisdictional effort to clean up the Chesapeake Bay. They say in spite of heavy development, in the 20 years since neighboring states and the federal government committed themselves to protecting it, at least it hasn't gotten worse.
They say the Mississippi River deserves that same kind of concerted effort.
Rep. Jim Oberstar, D-Minn., is sponsoring legislation to update the Clean Water Act. Oberstar says the Bush administration is interpreting a U.S. Supreme Court ruling in a way that causes unnecessary red tape and delays. His bill is scheduled for a hearing later this week.