Irrigation Water (Flood Irrigation)

State agency managing Arkansas groundwater allocation, including the Grand Prairie Critical Groundwater Area (CGWA) which supplies ~50% of US rice irrigation. Oversees the Grand Prairie Area Demonstration Project for aquifer recharge via surface water diversions. Identified 60% reduction in groundwater withdrawals as required for long-term sustainability.

The Bureau of Reclamation (Denver CO; agency of the US Department of the Interior; ~10,000 employees; ~$1.5B annual budget) is the federal operator of the Colorado River's major water infrastructure — Hoover Dam (Nevada/Arizona border; 726-foot concrete arch-gravity dam; 2,074 MW nameplate capacity), Glen Canyon Dam (Page, AZ; 710-foot; 1,320 MW), Davis Dam (Laughlin, NV), Parker Dam, and the Central Arizona Project (CAP) pump-lift infrastructure. Reclamation operates Lake Mead (the largest US reservoir by capacity: 26.12 MAF total; ~37 miles long when full) and Lake Powell (second largest: 24.32 MAF total; Glen Canyon). Reclamation administers the Law of the River — the collection of compacts, treaties, court decisions, and federal statutes governing Colorado River allocation — and makes annual shortage determinations triggering automatic water delivery cuts to Arizona, Nevada, and Mexico. Under the 2007 Interim Guidelines (amended by the 2019 Drought Contingency Plan), Reclamation declares shortage tiers based on Lake Mead elevation: Tier 1 (<1,075 ft elevation), Tier 2 (<1,050 ft), and Tier 3 (<1,025 ft). Each tier triggers progressively larger cuts to Lower Basin allocations (Arizona bears ~60% of shortage cuts due to Arizona's junior water rights under the 1968 Colorado River Basin Project Act). Reclamation is simultaneously the regulator, the infrastructure operator, and the allocation enforcer for the most contested water resource in North America.

Largest irrigation district serving the California Sacramento Valley rice belt. Receives Central Valley Project water from Lake Shasta via Bureau of Reclamation; serves ~240,000 acres of rice and other crops in Glenn and Colusa counties. 100% CVP water allocation in 2023-2024 after near-zero (0-18%) in 2022 drought.