Overview

The mighty Colorado River originates in the Rocky Mountains and flows more than 1,400 miles through the American southwest and the Republic of Mexico. The Colorado River Basin extends over nearly a quarter of a million square miles in seven states providing water for more than 25 million people and 3.5 million acres of agricultural land. Because much of the demand for Colorado River’s water and power—the river provides about 15 million acre-feet of water and12 billion kilowatt hours of energy annually—stems from cities located far from the river corridor, the river is dotted with dams and diversions. The Colorado River provides recreation opportunities such as swimming, boating and fishing, and natural resources in habitat for aquatic, marsh and riparian species, including both resident and migrant species.

Law of the River

In 1922, the Colorado River Compact divided the Colorado River into Upper and Lower Divisions and Upper and Lower Basins. The Upper Division States include Colorado, New Mexico, Utah, and Wyoming, and the Lower Division states include Arizona, California, and Nevada. The Lower Basin extends from Lee’s Ferry below Glen Canyon Dam to the Southerly International Boundary (SIB) with Mexico, and is referred to as the lower Colorado River. Hoover Dam is the northernmost facility on this stretch of river managed by the Bureau of Reclamation. Operations on the lower Colorado River are governed by various laws, treaties, and court decisions collectively referred to as “The Law of the River”. The Law of the River covers discretionary and nondiscretionary actions by the Reclamation related to operation and maintenance of the lower Colorado River and names the Secretary of the Interior as water master for the river.

Endangered Species

The Yuma clapper rail, a species native to the lower Colorado River, was listed as endangered in 1967 under the precursor to the Federal Endangered Species Act. In 1980, the native bonytail fish species was listed as endangered under the Endangered Species Act (ESA), and in 1991, the razorback sucker, another of the lower Colorado River’s native fish species, was listed as endangered. In 1994, areas of the lower Colorado River were designated as critical habitat for these two endangered fish species. In 1995, the southwestern willow flycatcher was federally listed as endangered. The U.S. Fish and Wildlife Service (USFWS) proposed critical habitat for the southwestern willow flycatcher in October of 2004. With the listing of several species as endangered along the lower Colorado River, and with the prospect of more species becoming listed in the future, there was a clear need for a long-term program that would balance the interests of water users with conservation of endangered species.

Lower Colorado River Multi-Species Conservation Program

After critical habitat was listed for the razorback sucker and bonytail in 1994, representatives from agencies responsible for water and power management along the lower Colorado River met to discuss a comprehensive plan to conserve native species and their habitats in compliance with environmental compliance under the Endangered Species Act. In April 1997, the USFWS issued a Biological and Conference Opinion to Reclamation covering routine operations and maintenance activities along the Colorado River from Lake Mead to the SIB. That biological opinion served two purposes: it provided Reclamation with Endangered Species Act compliance through 2002 (it was subsequently extended through 2005) and called for stakeholders along the lower Colorado River to develop and implement the Lower Colorado River Multi-Species Conservation Program (LCR MSCP). On April 4, 2005 Department of the Interior Secretary Gail Norton and representatives from agencies within Arizona, California, and Nevada signed documents to implement the LCR MSCP.

Updated November 26, 2012