Imperial County, California: drinking water report. Imperial County sits at California's southeastern corner along the Mexican border, with a population of…
Imperial County sits at California's southeastern corner along the Mexican border, with a population of about 180,000. The county is one of the hottest and most arid places in the United States, and its water comes almost entirely from the Colorado River via the All-American Canal. The Imperial Irrigation District manages water distribution for both agriculture and municipal use. Agriculture dominates the county – this desert landscape produces billions of dollars in crops annually using irrigated Colorado River water.
The Salton Sea, a shrinking inland lake in the county's northern section, is an environmental crisis in slow motion. As agricultural runoff feeds the lake and evaporation outpaces inflow, salinity has increased to levels exceeding ocean water. According to the Imperial County Air Pollution Control District's 2024 report, exposed lakebed – called playa – generates dust storms carrying pesticide residues, heavy metals, and fine particulate matter that affect air and water quality across the region.
Colorado River water delivered to Imperial County carries high total dissolved solids – averaging 700 mg/L according to USBR monitoring data. Perchlorate from the former PEPCON rocket fuel plant upstream in Nevada was historically present in the river, though levels have declined since cleanup. The EPA's UCMR5 data shows low-level PFAS detections in one county system.
Imperial County's water is hard and mineral-rich by nature – that is a characteristic of Colorado River water, not a failure of the treatment system. For taste and scale reduction, a reverse osmosis system or water softener helps.
Check your water for the latest monitoring data in your area. For TDS and taste, reverse osmosis is the most effective household solution. Our water filter guide includes systems designed for hard-water regions. Pull your detailed report for historical data, and visit our California page for statewide context.