WASHINGTON  Mon Jan 12, 2015 3:44pm GMT

The U.S. Supreme Court on Monday rejected a challenge by California growers and local water management agencies to federal guidelines that limit water diversions to protect the Delta smelt fish.

The decision not to hear two related cases means a March 2014 ruling by the 9th U.S. Circuit Court of Appeals siding with the federal government remains intact.

The federal guidelines, issued under the Endangered Species Act, say the state should reduce exports of water from north to south California. The plan leaves more water in the Sacramento Delta for the finger-sized fish, which is a protected species that lives only in the wetlands stretching north of San Francisco.

The dams and rivers that control water in the Central Valley Basin in California are overseen by the U.S. Bureau of Reclamation, a federal agency.

The endangered species law requires the federal government to avoid actions that would jeopardize a protected species. Agencies are required to consult with the U.S. Fish and Wildlife Service, which then issues a report that addresses the potential impact.

At issue is a 2008 report by the U.S. Fish and Wildlife Service that concluded that the fish's existence was threatened and recommended limited exports of water to farmers and southern California. Farmers and allies sued, and a lower court called the federal biological opinion "arbitrary and capricious."

The appeals court said the lower court should have been more deferential to the Fish and Wildlife Service.

The two related cases are Stewart & Jasper Orchards v. Jewell and State Water Contractors v. Jewell, U.S. Supreme Court, Nos. 14-377 and 14-402.