Commission workshop recap, 5/12/2026: Commissioners learn of 'Enhanced Geothermal' potential. Plus, details about last year's oil spill and more.

Commissioners got their first look at an energy resource Tuesday that could be construed as a type of “hydropower” that uses water heated to steam by the earth’s core instead of the cold mountain runoff and ever-flowing Columbia River that powers Grant PUD dams.

Staffers, May 12, delivered a crash course on “Enhanced Geothermal” energy to familiarize commissioners with that energy source.

The high-level course will help commissioners decide whether to join Chelan and Douglas PUDs in their ongoing effort to explore the feasibility of geothermal as an around-the-clock-available, carbon-free energy source.

The analysis, including drilling test “wells” more than 3 miles deep, will determine if our region contains sufficient geothermal “hot spots” to convert the steam they emit into electricity for our customers.

Staff expressed optimism that conditions do exist in Grant County for “Enhanced Geothermal” technology that could one day power a steam plant capable of generating 500 or more megawatts of electricity.

If commissioners move forward, Grant PUD would share the cost of the $22 million analysis with Chelan and Douglas PUDs, who began their research several years ago and have already hired a contractor for the job. Grant PUD’s share would be about $7 million.

Grant PUD Engineer Dave Dempsey told commissioners the process draws on lessons from gas and oil industries’ experience drilling deep wells to extract those fuels. Enhanced Geothermal uses vertical and horizontal drilling to reach deep into the rock heated by the Earth’s core several miles below the surface. Cold water is injected into the hot rock via injection pipes to create steam that rises to feed a steam turbine unit to create electricity.

But unlike “fracking,” the process used to extract gas and oil, Enhanced Geothermal targets hot rock. It’s a heat-exchange operation, not for resource extraction, Dempsey said.

The spent steam, as cooled water, would then be pumped back into the earth in a closed-loop system to replenish the geothermal source.

The process does not cool the geothermal source nor contaminate ground water, Dempsey said.

Commissioners will study the information and are scheduled to vote at their May 26 commission meeting on whether to participate in the analysis with Chelan and Douglas PUDs.

See the full presentation on pages 1-22 of the workshop presentation materials. The presentation includes an Appendix of frequently asked questions about geothermal power. Commission workshops are not recorded. 

Faulty oil-detection system caused December spill into the Columbia

Failure of an automated oil-detection system caused approximately 84 gallons of turbine oil to spill into the Columbia River from Priest Rapids Dam, Dec. 3, 2025, an extensive, root-cause analysis by Grant PUD experts has concluded.

The spill occurred after a crew had completed routine maintenance on the dam’s P6 turbine/generating unit and was refilling it with turbine oil pumped through a series of pipes from a holding tank. The oil overfilled and spilled into the “sump” – a type of catch basin for the dam that normally contains only excess water.

Unit P6 is one of three of the dam’s 10 turbine/generating units that has yet to be rehabilitated. It doesn’t yet contain a device that accurately counts gallons of oil pumped into or out of the unit, making a precise count difficult.

Isolated from the river, the dam’s sump is fitted with an automated alert system that, when operating correctly, notifies crews when it detects the presence of oil and stops a pump from transferring the contaminated water into the river.

The investigation concluded that the system correctly detected the presence of oil but failed to trigger the notification system and stop the pump on the day of the incident.

Crews have since inspected and correctly calibrated the oil-detection system and will conduct more in-depth tests during future scheduled maintenance. The same inspection was carried out at Wanapum Dam, approximately 20 miles upriver.

“We take our Columbia River ecosystem and spill incidents very seriously,” Rey Pulido, vice president of Power Plant Operations, said. “This one was highly preventable but alerted us to deficiencies. Our staff, including our most-experienced team members, have been instrumental in recommending improvements to our maintenance procedures and are deploying them going forward.”

The incident launched a swift, eight-day emergency-response involving Grant PUD staff in close collaboration with the state Department of Ecology and Grant PUD’s in-water contractor GrayMar Environmental, which deployed absorbent booms to contain the oil.

The effective response resulted in no documented harm to wildlife, the environment or drinking-water inlets in the Tri-Cities area, downriver. Clean-up efforts were declared “substantially complete” Dec. 10, 2025.

See the full presentation on the spill’s root cause report on pages 23-31 in the workshop presentation materials here.

Commissions also:

-- Received an update on the Moses Lake Transmission Expansion Plan (MTEP). The proposed project would be constructed in two phases. Phase 1 includes construction of a new switchyard in the Wheeler Industrial Corridor and two new transmission service loops, providing much-needed redundancy. Phase 2 would possibly interconnect with the Bonneville Power Administration’s 500 kV line, include an additional switchyard, and construct a new 230 kV transmission line from Rocky Ford to the Wheeler Corridor. The project is anticipated to deliver approximately 445 MW of additional capacity to Moses Lake between 2035 and 2037. To learn more see pages 65-79 in the workshop presentation materials.

-- Received the quarterly business report from the Environmental Affairs team, including details about salmon and steelhead tagging and helicopter-release project that’s part of a mandatory, 10-year fish-survival check in with the agency partners who track Grant PUD’s environmental efforts. Read more about the tagging project here. See the Tuesday’s presentation to the commission on pages 32-42 or the workshop presentation materials here.

-- Received the quarterly business report from the Cultural Affairs team.  See the presentation on pages 42-56 in the workshop presentation materials here.