Using Aquifer Storage and Recovery in the Tualatin Basin to Provide Water Security to a Small Municipality

The City of Cornelius, Oregon, has relied solely on water from the Tualatin River provided by the City of Hillsboro through the Joint Water Commission (JWC) to meet its drinking water demands. To meet future peak demands, the City initiated an exploratory drilling program to assess the feasibility of completing an aquifer storage and recovery (ASR) well within the Columbia River Basalt Group (CRBG) aquifer. In addition to meeting future peak demands, the City’s ASR program will provide a cost-effective way to store treated drinking water within the City and act as a critical facility. The City estimated that an aboveground storage tank would cost approximately $4 million to store 2 million gallons (MG), but a successful ASR well could store more than 50 MG for roughly $3 million.

In this small municipality, with a growing population and a changing climate, ASR will provide a cost-effective opportunity to use natural resources in a progressive and ecologically responsible manner. It is widely anticipated that warmer summers and declining snow packs will lead to diminished streamflows. By storing water during the winter, when precipitation and runoff are available, there will be less need to use valuable surface water during the summer months.

Using ASR to store water underground will provide the City with water security in the event of catastrophic dam or reservoir failures (which are a concern for the JWC’s Hagg Lake storage impoundment) that could result from a major subduction zone earthquake. Having an ASR program and an onsite generator will provide the City with a reliable backup water supply to meet the challenges of a growing municipality, including annual changes to the water cycle and the potential for catastrophic events.