Like the rest of the former Soviet Union, the Baltic states were once ecological disasters. But while Russia continues to be an environmental nightmare, Estonia, Latvia, and Lithuania are investing serious resources into cleaning up their environments — in the interest, government officials say, of gaining entry into the European Union. To do so, they must modernize aging refineries, reduce air pollution, meet E.U. standards for drinking water and forest management, and generally bring their laws into line with those of other member states. The E.U. might withhold invitations for full membership for a while, but the bloc is already helping to finance environmental improvements in the Baltics, such as closing a landfill in Lithuania, renovating water and sewage facilities in Latvia to reduce pollution in the Baltic Sea, and beginning to clean up more than 1,500 former Soviet military facilities in Estonia.