Ecology officials: ‘High hazard’ dams in Yakima, Benton counties aren’t hazardous

Fifty dams in Washington state have been identified as being high hazard and in poor condition, including seven in Yakima County and three in Benton County.

However, dam safety officials at the Washington State Department of Ecology said those classifications can be misleading and do not indicate that a dam is a threat to public safety.

The list of dams in poor condition in Washington state included seven dams located in Yakima County:

  • Den Hoed Dam No. 1 in Sunnyside
  • Evans Konnowac near Moxee
  • Coleman near Sunnyside
  • Black Rock Orchards in Moxee
  • Parker Reservoir in Yakima
  • Evans Pond in West Valley
  • Roy Farm Irrigation Pond in Moxee

Benton County also has three dams listed as being in poor condition: Gap Road Reservoir in Prosser, Paterson Ranch Reservoir in Paterson and Blair Reservoir in Kennewick.

The Blair Reservoir Dam is located on Elliot Lake and falls under downstream hazard category 1B, which means if the dam were to fail and release the reservoir, the lives of 31 to 300 people living in homes downstream might be at risk.

“Hazard assessment is associated with homes below the dam, so if you have a lot of homes, you have a high hazard, but it could be in perfect condition,” dam and well manager Gary Myers said.

Engineers inspect certain dams on a five-year schedule and work to determine if the dam owner is in compliance with state rules and regulations and provide a list of any existing problems that need to be corrected.

They also provide a rating based on the dam’s condition — from satisfactory to fair to poor to unsatisfactory — based on the number and severity of any deficiencies they may have.

“Unsatisfactory means that the dam is not performing as designed at all and it needs to be addressed immediately,” said Jodi Goodman, who handles dam grants and compliance. “Poor is like, well, if you wait too long, you know, it could become unsatisfactory.”

Goodman said that rating remains in place until the next inspection is completed, but dam owners are required to fix any problems with the dam in the meantime in order to get back in compliance.

The Roy Farms Irrigation Pond dam was last inspected in 2018 and was rated in poor condition. Goodman said they’ve been able to correct nearly all of their deficiencies since then.

Goodman said those corrections included clearing vegetation, providing information on new modifications, updating their emergency action plan and creating an operations and maintenance manual.

“Roy Farms has addressed everything except for the evaluation,” Goodman said. “They’re having a problem getting the funds to get the stability assessment.”

Goodman said the dam owners were told it would cost $18,000 to do the stability analysis, which the state is requiring for older dams that may not have previously been analyzed for seismic stability.

Other dams on the list have corrected many of or all their deficiencies since the last report was made. Paterson Ranch Reservoir is now in fair condition, while Gap Road Reservoir is in satisfactory condition.

Goodman said they check in with the dams every 30 days to see how much progress has been made in correcting deficiencies.

“They’re usually easily mitigated and there’s no cause for concern for a community member,” Myers said. “If there’s any condition that actually could result in an immediate hazard, we stop all of our work and and address that and make sure there’s an immediate response.

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