GROUNDWATER DEVELOPMENT

PROPERTY TRANSFER
REMEDIAL INVESTIGATION & CLEANUP
EXPERT WITNESS
WELLHEAD PROTECTION
SOLID WASTE COMPLIANCE
WATER RIGHTS SUPPORT
DATA MANAGEMENT
GROUNDWATER MODELING
WATERSHED ASSESSMENT
AQUIFER STORAGE & RECOVERY
• Thurston County
• Clallam County
WASTEWATER & STORMWATER RECHARGE
 

Client: Clallam County
Project: ASR Feasibility Assessment
Location: Clallam County, Washington

Background
Prompted by Washington’s HB 2514 Watershed Planning Act, regulators are considering ASR as a statewide approach for storing water for peak summer supplies and instream flow enhancement. We evaluated the usefulness of ASR in the western portion of Water Resource Inventory Area (WRIA) 18, which includes Morse Creek and the Elwha River.

Challenges
Prior to our work, no detailed hydrogeologic evaluations had been conducted in the study area. In addition, stakeholders expressed divergent needs for ASR and additional water. For example, the City of Port Angeles enjoys abundant inchoate water rights; however, using these rights would affect instream flows in the Elwha River. The Lower Elwha Klallam Tribe is lobbying for additional water to bring back the anadromous Elwha River salmon run. Complicating matters is the imminent removal of the Elwha River dams.

Approach
We developed a conceptual hydrogeologic model using basic tools. Several hydrostratigraphic cross-sections were drawn to understand the extent of various aquifers and the degree of confining pressures they impose on the groundwater system. We mapped regional flow directions to evaluate the potential for groundwater to leak from the cross channels that incise deeply into the glacial soils. Using Geographic Information Systems (GIS) techniques, we mapped aquifer transmissivity based on information in our database of over 500 well logs.

Outcome
Our analysis found some potential for storing and recovering small quantities of drinking water—about 1 MGD. However, these quantities are unlikely to be useful for augmenting instream flows in the Elwha River, which needs at least 5 to 10 MGD to derive benefits. ASR may be effective for enhancing flows in Morse Creek, the smaller of the two streams.

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