Jul 5 2015
In the Fall of 1977, a frantic city manager made a 2:00 AM call to the engineer responsible for starting up the Tahoe-Truckee Reclamation Plant. The manager screamed into the telephone, “I don’t care what I promised, shut off that fire hydrant you’re using to fill the plant with water!”
“Why?”, the engineer asked.
“You’re draining the city water tower…the pressure is below fire protection levels.”
The tiny town of Truckee, population 12,000, had one water tower supplied by wells for the municipal water system. Following a meeting with the city manager, the startup engineer was allowed, before turning sewage into the plant, to use the city water at a fire hydrant to fill the new sewage line with clear water to test the systems through the newly constructed influent line. It had seemed like a good idea, however the supply pumps lifting water to the tower couldn’t keep up with the outflow.
Now let’s raise the stakes. Instead of the municipal water system in Truckee, consider the water system in San Diego County, population 3.2 million. Would it ever be possible for the pressure in some areas to fall below fire protection levels? Although we’re talking about the sophisticated and complex system of water treatment plants, pumps and the pipelines that underlie the County, the Truckee model is not as far-fetched as it may seem.
When outflow is less than inflow, water physics takes over. No attempt will be made in this brief synopsis to cover the operational details of how this can happen. Only those who have access to the distribution systems and knowledge of the operational sequence could fully detail the scenario where the County water systems fail to provide water to all of the systems at the pressures required for full fire protection coverage.
However we do know that water at the proper pressure would be routed to critical facilities like hospitals, leaving non-critical residential units to suffer.
Fast forward to April 30, 2025. By then the San Diego area will have survived fourteen years of drought, possibly mitigated by El Ninos in 2015 and 2019 that helped fill local reservoirs, but did not add to the major sources of supply, the State Water Project and the Colorado River.
Like all previous winters the snow levels in the high Sierras are non-existent. Farmers had long since moved their farming operations to where the water was, but to keep the salt water in the Delta from overtaking the freshwater from the Sacramento and San Joaquin Rivers, water was allowed to flow to the ocean instead of through the massive pumps that would take some of it south.
As a result, Los Angeles and San Diego are allowed only a fraction of needed water from the State Water Project, depending nearly entirely on the Colorado River. That over-allocated river is dying from a drought of its own in the Upper Colorado River Basin. Both Glen Canyon Dam and Hoover Dam are at “dead pool”, where inflow and outflow are equal, as forecasted in the early part of the century. The West is one huge dustbowl.
In San Diego, the Carlsbad desal plant has been up and turning out 50 million gallons per day since 2016, but the long awaited 15 mgd Pure Water Facility is yet to meet the construction deadline of 2023 due to political wrangling and bureaucratic bungling. The 68 mgd addition to the same plant due to come on line in 2035 is not yet in design. Despite gargantuan efforts by the Water Reliability Coalition and a succession of mayors to accelerate the Pure Water facilities, less than fifteen percent of the water used in San Diego is supplied locally.
Local reservoirs filled during the two previous EL Ninos are now at ten percent of capacity and dropping rapidly with water usage in the San Diego area at 350,000 acre-feet per year despite the browning of San Diego by draconian water conservation edicts.
Inflow is less than outflow, and unless the laws of physics are repealed, various pressure zones in the San Diego area are affected. There is no 2:00 AM call to the startup engineer to remedy the situation. Only the cries for help from local residents who, when they open their shower valve for the morning shower, find the water dribbling out.
“You know what?”
“Maybe that recycled water idea isn’t so bad after all.”
By Milt Burgess • Blog • 0 • Tags: augmentation, California Aqueduct, Colorado River, conservation, Direct, dry centuries, El Nino, global warming, Human-caused climate change, La Nina, MWD, potable, precipitation, purification, purple pipe, rainfall, Reservoir Augmentation, residential water user, SDCWA, State Water Project, water infrastructure, water rate hike, water rates, water Storage, wet centuries