Water System ASR Study

On October 17, 2025 the City of Molalla and consultant Summit Water Resources held a kickoff meeting that signaled the beginning of an Aquifer Storage and Recovery (ASR) Feasibility Study. This study is the next step in the progression toward identifying and implementing a secondary water source for the City of Molalla (see alternative source memorandum in the Documents section).

An ASR is basically the use of a well to store water that is pumped in from an external source, then withdrawn (typically up to 95%) when needed by the City. In short, it is a secondary water source that can provide resiliency to the existing water system by using surface water to create a groundwater supply. ASR has been successfully used by municipalities in Oregon for over 25 years to more efficiently manage water resources.

Molalla currently has about 4.5 million gallons per day worth of water rights on the Molalla River during high flows (i.e. the wet season). An ASR is a natural fit for the seasonal nature of about half the city's water rights and has the added bonus of providing a very positive environmental impact by replenishing groundwater in an area with higher than average agricultural irrigation needs and declining groundwater level issues (see Gladtidings Groundwater Limited Area)

The purpose of this study is to determine whether or not Molalla has a viable location(s) for an ASR facility and, if so, to estimate the cost to construct one at said viable location(s). This work is listed as a high priority capital project in the City's Water Master Plan and is being funded by 2 grants from Business Oregon and Oregon Water Resources Department!

*Note - The City also received funding approval from the Infrastructure Finance Authority to Design and Construct a new Molalla River Intake Structure to replace the existing "Temporary Emergency" intake constructed in 1997 after the 1996 floods destroyed the permanent one. The Pre-Design report for that project is also available in the documents section.