Ecology sees improvements at several Yakima County dams previously found to be in poor condition

The Washington State Department of Ecology has seen improvements at several high-hazard irrigation dams in Yakima County previously found to be in poor condition.

Many of the local dams on the list recently published by The Associated Press aren’t what people typically think of when they think of a dam, according to Craig Jordan, a geotechnical engineer with Ecology’s Dam Safety Office.

“These are not the big concrete arches or gravity dams that you see along the Columbia,” he said. “These are small irrigation ponds.”

Still, the state monitors dam conditions and works with owners and operators to ensure they meet safety standards. Ecology regulates more than 1,100 dams, most privately owned.

Condition versus hazard

Dams are categorized both by their physical condition and by the hazard they pose if they were to fail.

The hazard scale, which ranges from low to significant to high, reflects the potential impact on people or the environment, according to information from Ecology. A dam has to meet specific design standards depending on its hazard level.

“I like to remind people that the hazard classification has nothing to do with the condition and everything to do with the population below the dam,” Dam Safety Office Manager Gary Myers said. “A high hazard dam has a higher population (downstream) than a low hazard dam.”

Dam conditions range from satisfactory to fair to poor to unsatisfactory based on assessed safety deficiencies.

An unsatisfactory dam has a safety deficiency that requires immediate action.

A dam in poor condition typically has safety deficiencies, and repairs are necessary. At this stage, failure could realistically occur.

A dam in fair condition is one that is maintained well but has some small areas for improvement, Myers said.

“Typically, it’s pretty trivial stuff like brush in the spillway, that sort of thing,” he said.

And a dam in satisfactory condition has no recognized safety deficiencies.

A variety of factors can affect the condition of a dam, including maintenance, upkeep and geotechnical or hydrological loading conditions.

“It’s a case-by-case basis,” said geotechnical engineer Gus Ordonez.

Current conditions

Some of the Yakima County dams found to be in poor condition have undergone repairs and their conditions have improved, while others are still awaiting inspections and repairs.

Here’s where the conditions of the dams stand today, according to information from Ecology.

Black Rock Orchards Dam

A dam breach analysis from 2015 indicated that hazard creep has occurred downstream of the dam.

Geotechnical engineer Jordan said this means housing or business development has occurred downstream, raising the hazard level, so the dam has to meet increased design standards.

This dam was reinspected in 2020, and Ecology found that the dam and spillway met the necessary standard. The dam will be upgraded to fair condition following completion of a periodic inspection report.

Coleman Dam

This dam is no longer under monitoring by Ecology because the owner removed a section of the dam. Ecology said the dam should not have been classified as being in poor condition. It is low-hazard and did not naturally retain water — someone had illegally dumped wastewater into the pond.

Den Hoed Dam No. 1

This dam was reinspected in 2021 and remains in poor condition.

Evans Konnowac Dam

This dam was reinspected in 2021 and will be upgraded to fair condition following completion of a periodic inspection report. Repairs were made to resolve damage to the downstream slope caused by ATV traffic.

Evans Pond or Evans Far West Pond

This dam was reinspected in 2021 and will be upgraded to satisfactory condition following completion of a periodic inspection report. Damage to the downstream slope has recently been repaired, and the owner has developed an emergency action plan for the dam.

Parker Reservoir Dam

This dam is in poor condition and is scheduled to be inspected this year.

Roy Farm Irrigation Pond or Roy Farms Jerrys’ Pond Dam

This pond was inspected in 2018 and was found to be in poor condition. Recent upgrades bumped its condition up to fair. Erosion along the bank was repaired and the spillway was reworked, Jordan said.