RIGHTLY, human beings are the priority of the first responders working in New Orleans. But over the next few days and weeks, authorities must not lose sight of Hurricane Katrina's long-term impact, not only on human beings but also on the land, water, marshes, fish and animals near the city. At the moment -- with the Environmental Protection Agency's permission -- the floodwaters that have covered the city for two weeks are being pumped into Lake Pontchartrain and the Mississippi River, where they will make their way into the rest of the Mississippi Delta and the Gulf of Mexico. At a minimum, that water contains pesticides, herbicides, household chemicals, gasoline from cars and at least two large oil spills, asbestos from building materials, heavy metals from batteries, whatever has leaked out of local toxic waste dumps and Superfund sites, bacteria from corpses and animal carcasses, and dirt containing unusually high levels of lead, long present in New Orleans's soil. No one knows what chemical reactions might take place in that water, which has been warm and stagnant for nearly two weeks. There are no precedents to help assess what its impact on the environment will be. As Darryl Malek-Wiley of the Delta Chapter of the Sierra Club put it, there is "no way scientists could ever recreate this mixture in a laboratory."

Local and federal authorities are right, at this stage, not to engage in scaremongering. Ecosystems do recover from disasters, both natural and man-made. A recent report on the Chernobyl disaster showed that the impact on people and the environment had proved much less than expected. But because this kind of water pollution is unprecedented, and because it could cause permanent damage to drinking water, agriculture and the fishing industry in the region -- and could damage the region's viability and even its habitability -- it is extraordinarily important that the EPA continue its daily monitoring of the floodwaters, while they remain in the city and after they have been pumped out.

At the moment, the EPA has about 100 people in New Orleans, doing exactly that. The danger, over the long term, is that with so many other projects requiring government resources, the EPA will not be given the staff and resources it needs to continue to track whatever damage the floodwaters are slowly wreaking on the region's water and soil. The agency is, in the words of one spokesman, "doing what we can with the resources we've got," including deploying employees from other parts of the country to join those already in the region. As Congress, the administration and others work on the recovery in coming months, they must not allow those numbers to drop further. The EPA mission is critical.