by Patrick and Lindi Doud
The sole source of water for the community of Los Osos is the Los Osos Groundwater Basin, which has suffered from overdraft, seawater intrusion, and nitrate pollution for decades, exacerbated by the reckless building boom in the 1980s. In 2015, the California Superior Court for the County of San Luis Obispo adjudicated this basin, and the resulting Stipulated Judgement established the Los Osos Basin Management Committee (BMC), tasked with 1) stopping seawater intrusion and 2) creating a sustainable water supply for the population. The BMC consists of 1 director from each of the 3 water purveyors and 1 from the county, representing the unmetered private well owners.
During the ten years since the BMC established its Basin Management Plan and has attempted to implement it, it has relied on groundwater modeling; first, a steady state model, and just this year, a more advanced and accurate transient model. However, a strain between the County, with its interest in increasing development and property tax revenue, and the water purveyors, who bear the responsibility of providing safe, reliable water to the population, has been growing. At the Dec. 16, 2025, Board of Supervisors meeting, this strain was on full display, with the County wielding its power to override the purveyors and undermine the intent of the Basin Management Plan.
When the Transient Model was released earlier this year, the County hailed it as a vast improvement and hoped it would show the water basin to be healthy and able to support future growth. But it showed the opposite. The current amount of pumping over the last 5 years continued the overdraft of the Basin and allowed seawater to intrude further inland.
The Basin Management Committee was alarmed, and voted for a 0% growth rate for the year of 2026, submitting a letter on October 24 informing the County of their decision based on the best available science. Then, when County Planning staff ignored these findings to recommend a 0.4% growth rate for 2026, the 3 purveyors on the BMC read the BMC’s recommendation letter at the Dec. 16 Board of Supervisors meeting before their vote. The Board ignored them and endorsed the 0.4% growth rate.
The clash between land use authority and a sustainable water supply for the community of Los Osos places the weight of responsibility squarely on the shoulders of the water purveyors, and their concern is evident and justified.