Aquifer Storage and Recovery (ASR) is the injection of drinking water into an aquifer (geological formation that holds water) for storage, with the intention to pump it out later for use. ASR was pioneered in Oregon and is being used more and more around the state. Western Oregon’s climate is well-suited for ASR because it rains for about nine months out of the year and then often has almost no rainfall during the months of July, August, and September. ASR wells can be charged (filled with water) during the winter when the rivers are at capacity and then pumped to provide water when the weather turns hot and dry and extra surface water is no longer available.

 

It is important to note that ASR alone cannot meet future storage needs in the region. It is a helpful tool for providing stored water during high summer demands.  However, ASR requires specific geological formations for successful water storage, and locations for ASRs with sufficient capacity and proper functionality can be difficult to secure.

 

 

Hillsboro Water (HW) depends on the Tualatin River for its water supply the majority of the year (approximately from November to June). HW typically uses about 14 million gallons a day (MGD), but during the summer months that demand almost doubles (due to outdoor irrigation), and use can approach 25 MGD. Unfortunately, the river supply runs opposite of demand. During the months of lowest demand, especially late winter/early spring, supplies are plentiful and rainfall and runoff can be so heavy that the river overflows its banks. Very little of the river water can be stored so it just flows away. Then summer comes around and the river drops. Hillsboro and its water supply partners must release water that has been stored in Hagg Lake and Barney Reservoir to meet demand.

 

The development of ASR wells will allow Hillsboro and its Joint Water Commission (JWC) partners to inject some of the excess winter flow into the ground and then pump it out in the summer when the river is low. This will become a critical supply once Hagg Lake and Barney Reservoir no longer store enough water to meet summer demands of all JWC customers.