The subsidence at Long Beach encompassed an area of 22 square miles sinkage ranging from 2 feet to 30 feet. The subsidence is attributed to pressure reduction due to oil production from the Wilmington oil field. The injection of saline water has successfully stopped the Long Beach harbor area subsidence. In addition, 15 years experience in injecting saline water into the Wilmington oil field has developed a technology that has successfully made an economic waterflood project. The overall economics have been improved through progress in water quality control to prevent corrosion and scaling and to maintain injectivity. The water quality control learned over the years is now being used to prepare the oil field produced brines for injection. Historically the produced brines have been disposed of into the harbor waters. However, the possibility of pollution of coastal waters exists, not only from contamination due to oil, chemicals, and fines, but also to an oxygen deficiency in the water that would be harmful to fish life. Through December 1968, 2.1 billion barrels of saline water have been injected into the Wilmington oil field (2.5 billion through December 1969). The bulk of this was ocean water produced from source wells open to sands 100 feet to 400 feet deep. The current injection rate of the field is 1.1 million barrels per day. Expanded use of the oil field's produced brine for injection is taking place and 550,000 barrels per day of this brine will replace source well water during 1969. The methods being used to clean the oil field's produced brine include: (1) filtration, (2) re‐cycling through the shallow source water beds, and (3) blending with fresh or other saline waters.