Glenn-Colusa Irrigation District History and Background



Glenn-Colusa Irrigation District (GCID) is dedicated to providing reliable, affordable water supplies to its landowners and water users, while ensuring the environmental and economic viability of the region.




The District’s appropriative water rights began on the Sacramento River with an 1883 filing posted on a tree by Will S. Green, surveyor, newspaperman, public official, and pioneer irrigator.  His first claim was for 500,000 miner’s inches under 4 inches of pressure and was one of the earliest and largest water rights on the Sacramento River.


GCID was organized in 1920, after several private companies failed financially, and a group of landowners reorganized and refinanced the irrigation district, retaining claim to Green’s historic water right. The disastrous rice crop failure of 1920–21 nearly destroyed the district at its inception, and the “great depression” took a further toll, making it necessary for the district to refinance in the 1930s.  Additionally, the United States purchased lands within GCID during this period, which would later become three federal refuges totaling approximately 21,000 acres.




Today, GCID is the largest irrigation district in the Sacramento Valley. The district boundaries cover approximately 175,000 acres; of which approximately 140,000 farmed.  There are 1,076 landowners in the District and an additional 200 tenant water users.  Additionally, GCID services 1,200 acres of private habitat land and 21,000 acres of protected federal wildlife refuges. Winter water supplied by GCID to thousands of acres of rice land provides valuable habitat for migrating waterfowl during the winter months.


GCID’s main pump station, its only diversion from the Sacramento River, is located near Hamilton City.  The District’s 65-mile long Main Canal conveys water into a complex system of nearly 1,000 miles of canals, laterals and drains, much of it constructed in the early 1900s.


GCID has a deep commitment to sustainable practices – both in managing the water supply, as well as preserving and protecting the environment, fish and wildlife in the region.  The District has completed numerous projects to ensure minimal impact of water diversion on fish and wildlife, as well as deliver water to maintain critical wildlife habitat.


The District headquarters are located in Willows, the county seat of Glenn County, approximately 90 miles north of Sacramento on Interstate 5. A five-member board of directors governs the District.  The annual budget is $15 million.




Current water supplies are diverted under the “Settlement Water Contracts” with the Bureau of Reclamation (Bureau).  The first Settlement Contracts were established in 1964 to allow the Bureau to operate and divert water for the newly constructed Central Valley Project. The contract was renewed for another 40-year term in 2005.  The contract provides GCID with water supply for the months of April through October for 720,000 acre-feet of base supply, and 105,000 acre-feet of Central Valley Project water that is purchased during the months of July and August.  During a designated critical year when natural inflow to Shasta Reservoir is less than 3.2 million acre-feet, GCID’s total supply is reduced by 25%, to a total of 618,000 acre-feet.


Additionally, the District has rights under a State Water Resources Control Board (SWRCB) permit to “winter water.” These rights run from November 1 through March 31 at a 1,200 cubic feet per second (cfs) diversion rate.  This water supply is used for rice straw decomposition and waterfowl habitat.


Looking ahead, GCID will remain focused on continuing to deliver a sustainable, reliable water supply by positioning itself to respond proactively, strategically and responsibly to California’s ever-changing water landscape.