WHY DID West Virginia officials have to order 300,000 people to give up tap water in and around Charleston, the state capital, for days? In part because they didn’t know the health risks associated with 4-methylcyclohexane methanol, the chemical that spilled from riverside storage tanks and into the water supply last week. And they still don’t, according to an Environmental Defense Fund analysis, because information on its risks to humans is amazingly scant.

Americans see pictures of brown, pollution-packed air in Beijing or red, chemical-saturated rivers in Hungary and may assume that the time of such spectacular environmental dangers has passed in the United States. That’s in large part because of regulations from the last century that protect the air and water against the riskiest sorts of pollution. But those laws sometimes fail because they aren’t perfect or because they aren’t perfectly applied.

The West Virginia water emergency reflects both. According to the state’s environmental chief, the storage plant dates to 1938, a time before modern environmental regulation. A downstream water treatment plant was old, too. Some rudimentary federal reporting and permitting rules covered the chemical storage site. Yet federal and state oversight were inadequate. The site was last inspected in 1991 .

In fact, a lot of environmental protection depends on state officials. Though environmentalists say that neighboring Maryland could use more personnel, they report that the state is stronger in its application of federal programs. Maryland officials say they inspect industrial facilities about once a year and more often after a violation is found. Virginia environmental officials say that chemical storage sites in the commonwealth are subject to strong building codes, but local fire officers are responsible for enforcement. The state’s Health Department says that it thoroughly examines upstream contamination risks when siting drinking water facilities. Yet, for existing ones, officials seem to rely on procedures to rapidly shut off water intake after spills have been reported. In West Virginia, state officials weren’t notified and the water wasn’t shut off in time.

Federal requirements, meanwhile, are spotty. Some quantities of some chemicals trigger notification requirements. But for many chemicals in regular use, federal law does not require safety data. That’s because the governing law, passed in 1976, presumed that chemicals in use at the time were safe. Bizarrely, to order testing on chemicals grandfathered in, the Environmental Protection Agency must offer evidence that they aren’t safe in an onerous bureaucratic process. A bipartisan chemical safety reform bill on the table in Congress would improve matters, but it hasn’t yet moved. It should.

A combination of state regulators using a bit of sense — like asking about an old tank farm next to a drinking water facility — and better federal law — like requiring more information on chemical safety — might have prevented or limited the damage and dislocation the people of Charleston have seen.