Water Factory 21

I was searching through some old news articles when I came across this one from California in 1988.

It provides a useful historical perspective on the Orange County Water District’s water recycling scheme known as Water Factory 21. This was the precursor to the recently opened (and much larger) Groundwater Replenishment System in California.

The danger: Barriers keep ocean at bay and freshwater supplies safe
Frank Mickadeit
17 January 1988
The Orange County Register

The biggest threat to the potability of Orange County's tap water lies just to the west, waiting for water-district officials to let down their guard.

Unchecked in the past, it has sneaked in, rendered freshwater wells useless, and quietly retreated. The intruder? The Pacific Ocean. The Orange County Water District and the Los Angeles County Department of Public Works have spent millions of dollars to hold back the sea, which, given a chance, will seep into local freshwater aquifers through underground channels.

Sea water, at about 32,000 parts per million salt, quickly can contaminate a ground-water supply, which, according to state guidelines, should not contain more than 500 ppm salt.

When the ground-water basin is at a high level, sea water cannot get in because the water pressure created by a full basin keeps it out. But when the freshwater basin is low, the pressure drops and the sea water can force its way in.

Numerous wells in coastal Orange County were lost to salt-water intrusion during the 1930s, '40s and '50s, when the water table dropped below sea level. The city of Newport Beach, for example, lost all of its freshwater wells and never has been able to reclaim them. It now imports water from the Metropolitan Water District of Los Angeles.

To stop the intrusion, water officials have built two sets of barriers.

Both work essentially the same way: A series of wells was drilled a few miles inland at points deemed most vulnerable to sea-water intrusion. Into the wells is pumped fresh water, which spills into aquifers located 90 feet to 420 feet underground.

The water helps keep the ground-water basin above sea level, which keeps the sea water out. Strung out over several miles, the wells form an underground blockade against the sea.

Without the barriers, "sea water could go as far as five to 10 miles inland over a long period of time," said James F. Reilly, director of water quality for the Orange County Water District. "Between the coast and five to 10 miles inland, there've probably been hundreds of wells that have been saved."

The first barrier, the Alamitos Barrier, was started in 1965 to cut off what is known as the Alamitos Gap, an underground channel at the point where the San Gabriel River flows into the Pacific Ocean.

Twenty-six injection wells and other facilities have been installed over the years on both the Los Angeles and Orange County sides of the river, at a cost of $3.5 million.

The Los Angeles County Department of Public Works, which manages the barrier system, injects 6.5 million gallons of water into the Alamitos Barrier wells each day.

The system is "fairly effective," said Ramesh Doshi, an engineer who monitors the barrier. In general, water on the seaward side of the barrier has several times the saline level acceptable in drinking water, while ground water on the inland side is at or below acceptable levels.

In 1976, the Talbert Barrier was built to keep sea water from entering the gap where the Santa Ana River empties into the ocean.

The Orange County Water District drilled 23 water-injection wells along Ellis Avenue between the Santa Ana River and Newland Street in Fountain Valley.

Between 6 million and 7 million gallons of fresh water are injected into the Talbert Barrier wells each day.

Rather than use water from a source that could dry up in drought years, the district taps an unending supply: Orange County sewage.

At Water Factory 21 in Fountain Valley, the district takes treated sewage from the nearby Orange County Sanitation Districts and subjects it to a sophisticated cleansing process that includes reverse osmosis, in which the water is filtered through a microscopic membrane.

The result is water that meets state drinking-water standards and actually has only about one-fifth as much dissolved solids as water from the Colorado River. Instead of being sent to customers, however, that water is injected into the aquifers, where it mixes with the ground water that eventually is pumped out and sent to homes and businesses.

Water Factory 21 and related facilities cost the district nearly $21 million.

"It's a fairly costly source of water, but it is necessary to protect a very large quantity of cheap water," said Gordon Elser, spokesman for the water district.

Despite their successes, officials are concerned that sea water may be intruding in coastal areas where there are no barriers. Traces of sea water have shown up in special test wells in the Seal Beach and Bolsa Chica areas, Reilly said.

Although sea water hasn't appeared in any wells that produce drinking water, the agency wants to head off a potential intrusion and this year plans to look at those areas as possible candidates for barriers, Reilly said.