A feasibility study found no major problems with locating the Dungeness Off-Channel Reservoir west of the River Road-Happy Valley Road intersection but cited two decades-old community dump sites that must be addressed, Clallam County commissioners decided on Jan. 25.

The study assessed seismic-geohazard issues, cultural resources and environmental problems at the 319-acre site as a prelude to the state Department of Natural Resources appraising the property for its impending sale to the county.

Chairman Mark Ozias of Sequim estimated the project will cost $25 million to $30 million, making it among the largest public works projects in county history.

The reservoir, which will cover 80 acres of surface area, is intended to guarantee water availability to area farmers and increase water flow for fish habitat in the Dungeness River.

Preliminary drawings indicate about 711,000 cubic yards of material will be excavated and 770,000 cubic yards will be needed for the berms.

“There may be insufficient material on site for the berms,” the report said.

Commissioners agreed to assess the cleanup-impact of the two community dump areas in a Phase 2 environmental study.

According to the report, the 2-acre Old Sequim Dump contains refuse from the 1920s and cars and trucks from the 1930s-1950s, and people still dump refuse there.

Some material dates to the 1870s, according to the report, which did not identify that material.

The 1-acre Happy Cat site has about four or five pickup-truck loads of garbage from the 1930s to the mid-1960s, the report stated.

The appraisal is not likely to be conducted for about three months, giving time for completion of the more detailed environmental study after the study is completed, commissioners learned.

The study Ozias and Commissioners Randy Johnson and Bill Peach reviewed this week also determined there are not significant issues with cultural resources, landslides and seismic dangers.

Recent studies by the U.S. Geological Survey had used LIDAR (Light Detecting and Ranging) images similar to radar “to infer the potential presence of earthquake faults just east of and possibly into the proposed reservoir,” according to the report.

The suspected presence of “possible traces of the Sequim Fault” was not borne out by onsite visits from two representatives of the U.S. Geological Service who scouted the Bell Hill area where those traces had been identified, the report said.

“They found no certain evidence of past faulting,” the report stated.

The threat of landslides also is negligible, according to the report.

“The dynamics of the river could be an issue once the reservoir is in place,” Johnson said.

County hydrologist Carol Creasey, who presented the report to the commissioners, said the reservoir is 200 feet from the bluff, but the configuration of the reservoir could change if need be.

Retired DNR employee Mike Cronin, the DNR property manager for the parcel for three decades when it produced timber for sale, was interviewed for the report. DNR funds were too limited to remove garbage from the site, he said.

On-site irrigation ditches and structures were periodically maintained by the irrigation companies, the report said.

“He was not aware of cultural or archaeological resources at the property but noted that there have been some culturally modified trees (i.e., cedar trees that had been harvested of their bark by local tribal members) in the area,” the report said.

Creasey said David Brownell, the Jamestown S’Klallam Tribe’s historic preservation officer, said in a communication to her that the report was “very well done” and “looks great.”

Brownell said more testing may be required if, for example, the site is further developed with roads.

During the past two years, the main parcel has been developed for public access with the addition of biking trails installed and maintained by the Olympic Peninsula Bicycle Alliance, Ozias said. The area also is used for trail walking.

The trails are unpaved and extend throughout most of the property, according to the report.

“Many of the trails will continue to be accessible,” Ozias said.

“Some internal trails that criss-cross the site will no longer be accessible.”

Creasey said as the project progresses, public comment sessions will be held and that Dungeness Meadows residents are being apprised of the project.

So far it’s been funded by state grants and will require additional state funds and, possibly, federal and county money, Ozias said.

The Dungeness Off-Channel Reservoir working group conceived the idea of the reservoir about 10 years ago.

Its members still include the county, city of Sequim, Jamestown S’Klallam Tribe, Dungeness Water Users Association, Clallam Conservation District, the state Department of Ecology and the Washington Water Trust.

The county is developing memos of understanding to determine “who is responsible for what” once the project is completed, Ozias said.

“For each partner, there will be a financial component to what that ongoing obligation looks like,” he added.

The report is available in the commissioners work session agenda packet at www.clallam.net.