Last week, Marin Municipal Water District won a legal victory when the state supreme court declined to review an appellate court ruling that found its environmental impact report of a proposed desalination plant adequate. In May, the appellate court overturned a ruling by Marin Superior Court Judge Lynn Duryee, who ruled that the EIR was lacking, writing that a desalination plant was “unnecessary because water conservation costs nothing, has no negative environmental effects and is more effective than the [desalination project].” The appellate court disagreed, ruling that the water district followed environmental law in its review process and that “differences of opinion” do not invalidate an EIR. The water district, which serves the San Geronimo Valley as well as 10 towns in the county, decided in 2010 not to pursue a desalination plant. The ruling leaves the option open if it ever decides to do so, though any future construction must be approved in a voter referendum and the water district would have to evaluate whether any conditions had changed since the environmental review was undertaken.