The tribe has joined the cities of Reno and Sparks in suing the agency that operates the Truckee, Calif., area's sewage treatment plant, claiming its $42 million expansion plan would harm the Truckee River. The lawsuit filed last month in Nevada County Superior Court in Nevada City, Calif., seeks to void the Tahoe-Truckee Sanitation Agency's approval of the project. The suit contends the agency should be forced to prepare a new environmental impact report because it failed to fully address the project's impact on the Truckee River and Pyramid Lake. It further claims the expansion could harm two downstream fish - the endangered cui-ui and threatened Lahontan cutthroat trout. Treated sewage effluent is discharged into the river. The Truckee flows east for about 100 miles from Lake Tahoe to Pyramid Lake, running through both Reno and Truckee, and is the Reno area's main water source. The plant, which serves the Truckee-north Tahoe area, reached 80 percent of capacity two years ago. Craig Woods, the sanitation agency's general manager, said he fears the lawsuit could halt future development in the rapidly growing Truckee area. He said the agency complied with strict California water quality standards and has "never had a significant water quality violation." The Truckee drops more than 2,500 feet in its trek from Lake Tahoe to Pyramid Lake on the desert floor. It traverses a microcosm of what the West has become in a century of development - from upscale tourist communities in the Sierra, through downtown Reno and finally to the farm irrigation canals of rural Nevada. It seemed a perfect place to study competing public attitudes about water conservation and environmental values. But four years, researchers "found almost no meaningful differences across the three communities - a water rich one, a rapidly growing metro area in an arid climate and an agricultural community struggling to maintain its share of dwindling water rights." They found poor people more likely to practice water conservation; most everyone worried about where water will come from in the future, and everybody hates "water cheats" who water on the wrong days. About half the water from Tahoe is sent through canals to the Newlands Irrigation Project, the first of its kind built in 1905. Water makes the desert bloom with cantaloupes and alfalfa around Fallon. It's the source of continual political feuding about the divisions for farming, residential use, historic trout runs and the endangered cui-ui in Pyramid Lake.