The Case of Pasadena’s Incredibly Shrinking Water Supply

Raymond Basin water level from 1920 to 2020 (Chart – PWP)

The aquifer that supplies about a third of Pasadena’s water supply is drying out and will become depleted unless major changes are made in how the Raymond Basin is managed.

By William J. Kelly

Groundwater from the Raymond Basin has been pumped at an unsustainable rate for more than 100 years, according to a 2018 report for Pasadena Water & Power.

Unsustainable pumping has caused the groundwater level to fall by 300 feet. The document also notes that cancer-causing contaminants in the aquifer emanating from the Jet Propulsion Laboratory threaten to make water pumped from the basin unfit for drinking unless they are cleaned up and better managed.

Morey Wolfson, former Pasadena Environmental Advisory Commission member, outlined the situation Wednesday evening at an online meeting organized by the Arroyo Seco Foundation. Wolfson also served on a city task force that helped Pasadena Water & Power put together a plan to address the growing water supply crisis.

He explained that Pasadena Water & Power’s plan calls for numerous water management improvements over the next 25 years at a cost of $425 million. The draft blueprint aims to bring Pasadena to the point where it can meet 50 percent of its water needs from the Raymond Basin. Today it gets 35 percent of its water from the basin and 65 percent from the distant Colorado River and San Francisco Bay Delta.

PWP’s plan would do that by replacing leaking water pipes throughout the city, which would reduce the need to pump water. It also calls for upgrading reservoirs, enhancing water conservation programs, and constructing local projects to better capture water from streams when it rains.

Even though the plan will raise residential water rates an estimated $13 to $17 a month and business rates by 10 to 15 percent, according to PWP, the plan still will be less expensive than increasing reliance on imported water. That’s because local groundwater from the Raymond Basin costs about $500 per acre foot while imported water costs more than $1,000 an acre foot. Each acre foot is enough to meet the water needs of about three households a year, according to the Water Education Foundation.

Another advantage of local water, according to PWP’s plan, is that the availability of imported water varies tremendously from year to year based on the Sierra Nevada snowpack. Enhancing the local supply will further ensure the city has water should a major earthquake sever the aqueducts that bring water to Southern California from distant areas.

The Pasadena City Council is expected to approve the plan sometime this winter.