The 2001 decision by the US Bureau of Reclamation to curtail water deliveries to farmers in the Klamath Irrigation Project of southern Oregon was based on a biological opinion prepared by the US Fish and Wildlife Service addressing requirements to protect two endangered fish species in the basin (short nose and Long River suckers, and coho salmon). Along with other protest activities, farmers and community members continued to challenge the “best available science” used to prepare the biological opinion. Noting gaps and uncertainties in the existing science, they challenged its use to make policy decisions that could so directly – and drastically – affect their lives. Without water, farmers could not grow their crops in this semi-arid land, or sell their farms whose value fell close to zero. In February 2002, the National Academies of Science released it own review of the relevant research, finding that there was insufficient science to support the action taken – withholding water deliveries in order to maintain the lake level to protect the endangered sucker fish. As in similar high profile natural resource issues, science was used to make and/or rationalize policy decisions in forums inadequate to deal with the contingent and dynamic nature of science. And, in the process, provided additional “evidence” to skeptics about unscientific science might be. The experience of the Klamath Basin will be used to illustrate research about preferred roles for scientists and differing expectations about what science can provide that lead to the clash of, at least, C.P. Snow’s “two cultures.”