Pressure from environmentalists has led a major company in Mexico to modify a planned salt-mining operation along the Baja California coast, the first time a company in Mexico has modified a project because of public input. But a number of enviro groups, including the Natural Resources Defense Council, are still protesting the salt works operation, saying it will harm gray whales that breed in the area. The project, a joint venture between Mitsubishi and the Mexican government, involves the construction of a 116-square-mile system of dykes and ponds where sea water will be evaporated, as well as a mile-long cargo dock. It would abut a U.N.-protected nature reserve, and this week a team of U.N. scientists is visiting the area to make a final recommendation on whether the project would endanger the area’s ecosystem.