If Americans seriously thought more evidence besides the Exxon Valdez disaster was needed to justify tougher laws to prevent and clean up oil spills, they now have it.

It comes in the form of no less than three major oil spills the past weekend involving Delaware, Rhode Island, and Texas.But the additional evidence should not have been needed. Last year alone, the Coast Guard reports, there were some 7,500 oil spills in the ocean, of which 250 were serious enough to require federal intervention.

In any event, let's hope these latest unhappy episodes breathe new life into congressional efforts to replace a hodgepodge of widely varying laws in 24 states plus four under-financed federal laws with a uniform, tougher, better-funded new national law on liability and compensation for oil spills.

But there's still no justification for the proposed moratorium on petroleum drilling in various offshore and other environmentally sensitive areas. The moratorium would merely make America more dependent on foreign oil, which would require more shipping of oil and thus increase the risk of oil spills. Two of the three spills this past weekend involved imported oil.

Even more helpful than a new federal law would be stepped up research to develop more effective methods of dealing with oil spills.

Although such methods have been somewhat improved, experts agree that the basic technology of dealing with oil spills has not fundamentally advanced in two decades.

The White House thinks the petroleum industry should give a higher priority to the development of chemical dispersants capable of dissolving spilled oil. But there are limits to what science can accomplish. Present dispersants are only marginally helpful. More effective dispersants could harm the environment as much as spilled oil. No wonder that decisions to use dispersants are often delayed.

Instead, how about routing tankers away from ecologically fragile shorelines even though the longer routes involved would add to the price of oil and gasoline? How about requiring double hulls on oil tankers to make these ships less prone to spills? How about getting tougher in enforcing the rules on how oil tankers are to be handled? And how about building more oil pipelines in an effort to eliminate some of the tankers?