During the 1950s and 1960s, the ocean moved about three miles inland in Orange County, due to increased ground water use and the resulting decreased water levels in the ground water basin. This resulted in seawater contamination of wells, which had to be decommissioned.
In the 1970s, OCWD installed an underground fresh water barrier to hold back the ocean. The barrier consisted of 26 injected wells along the coast that injected purified wastewater underground to create a fresh water mound above sea level, preventing ocean intrusion. Because of increased ground water use over the years, OCWD now is at a point where the barrier must be expanded. An additional eight wells will be installed to increase the amount of purified water that can be injected from 5 million gallons to 40 million gallons per day.