GSI finds no fatal flaws for Willow Creek managed‑aquifer recharge; recommends Phase‑2 data collection
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Summary
GSI Water Solutions told Gilliam County Court its desktop feasibility study of a managed aquifer recharge project on Lower Willow Creek found no fatal flaws, identified a practical storage target of about 1,100 acre‑feet, and recommended Phase‑2 on‑the‑ground data collection and a 50% funding match.
GSI Water Solutions presented results of a Lower Willow Creek managed aquifer recharge (MAR) feasibility desktop study and told the Gilliam County Court the review identified no fatal flaws but significant data gaps that require Phase‑2 work before a final feasibility determination.
Matt Thomas of GSI, the lead presenter, said the study was funded through an Oregon Water Resources Department feasibility grant with 50% local matches from Morrow and Gilliam counties. He said the absolute upper bound to supply all surface water users year‑round would be roughly 7,000 acre‑feet — “unrealistic” in scope — and that GSI and landowners agreed on a more practical near‑term storage target of about 1,100 acre‑feet for downstream users. Thomas translated that figure for commissioners: “Another way to think about that is that translates to about 370,000,000 gallons.”
GSI described the target storage aquifer as Columbia River basalts and identified a groundwater‑damming feature — the Willow Creek monocline — that pressurizes groundwater upstream and produces significant groundwater level declines downstream (in some wells up to about 200 feet). That pattern, GSI said, suggests storage opportunity north (downstream) of the monocline and little storage headroom upstream.
On water quality, Thomas said the limited available samples showed only minor treatment needs (bacteria, total dissolved solids, sediments, nitrates) and, importantly, no detected pesticides or herbicides in the available Willow Creek samples, but he emphasized the available dataset contains gaps. He recommended installing one or two stream gauges, collecting additional surface and groundwater samples, conducting geochemical analysis to assess clogging risk, and running pumping tests on existing wells.
GSI provided a rough Phase‑2 cost estimate of $250,000–$350,000 over one to two years and said a 50% cost match would be required by many state funding programs (so a match of roughly $125,000–$175,000). Thomas also warned that governance questions — who would operate, maintain, and allocate water from any constructed system — would require additional work and might favor starting with a single demonstration site.
Court members asked technical questions about injection methods and equipment. Thomas described retrofitting existing wells, injection/recovery equipment, and the need for monitoring. GSI offered to distribute the full report and information sheets.
Next steps: GSI recommended Phase‑2 on‑the‑ground data collection (stream gauges, water‑quality sampling, pumping tests and a preliminary system design) before further investment decisions.
