The Central Valley is a vital agricultural region that dominates the center of California, stretching 40-60 miles east to west and about 450 miles from north to south. It covers 22,500 square miles, about 13.7% of California’s total land area.
The Mexican Water Treaty of 1944 committed the U.S. to deliver 1.5 million acre-feet of water to Mexico on an annual basis, plus an additional 200,000 acre-feet under surplus conditions. The treaty is overseen by the International Boundary and Water Commission.
As adjacent Western states, California and Nevada share similar issues related to drought and limited water resources. Both states are participants in the 1922 Colorado River Compact and the 2003 and 2007 Quantification Settlement Agreements to allocate Colorado River deliveries. Also, about two-thirds of Lake Tahoe lies in California and one-third in Nevada, and the two states have formed a compact to work together on environmental goals for the lake.
Pyramid Lake in Nevada has long been a focal point in a tug-of-war between water stakeholders. There’s been a struggle for water in this arid land among the American Indians, farmers, cities, environmentalists and the people of Nevada and California. The lake is the site of the nation’s first reclamation project and the subsequent struggles among Nevada farmers, the Paiute Indian Tribe and the growing city of Reno over use of the lake’s water. In 1990 a settlement act attempted to resolve some of these competing uses.
The Sacramento Valley, the northern part of the Central Valley, spreads through 10 counties north of the Sacramento–San Joaquin River Delta (Delta). Sacramento is an important agricultural region, growing citrus, nuts and rice among many other crops.
The San Joaquin Valley stretches from across mid-California between coastal ranges in west and the Sierras on the east. The region includes large cities such as Fresno and Bakersfield, national parks such as Yosemite and Kings and fertile farmland and multi-billion dollar agriculture industry.
Until the early 1900s, central California’s Tulare Lake naturally appeared every winter as the southernmost rivers flowing out of the Sierra Nevada Mountains filled the dry lakebed with rainfall and melted snow.
Farmers adjacent to the lake also used the water to irrigate their lands. But the variable shoreline made growing seasons unpredictable. In response, Pine Flat Dam was built by the U.S. Army Corps of Engineers to control Kings River flows. The Kings River is still used extensively for irrigation.