GRAND COULEE - Hundreds of people flocked to the Grand Coulee, Chief Joseph and Rocky Reach dams last summer to participate in the D3 Geocache Challenge.

An estimated 500 people took part in the high-tech treasure hunt, Grand Coulee Dam public affairs officer Lynne Brougher said. About 300 earned the D3 patch, meaning they successfully completed the geocaches at each of the three dams, she said.

"We just started the program last summer season," she said. "This was definitely a trial to see how it would work and we felt it was pretty successful."

The D3 Geocache Challenge is a collaborative program between The Bureau of Reclamation's Pacific Northwest Region, the U.S. Army Corps of Engineers and the Chelan County Public Utility District. The three groups were recently recognized by the National Hydropower Association for the success of their program.

They received the Outstanding Stewards of America's Waters Award for public education during the NHA annual conference in Washington, D.C. recently.

When geocaching, people use GPS devices or smart phones to receive clues to search for hidden items. Brougher said when people discover the items in the D3 challenge, they learn facts about each of the dams and renewable energy.

"The goal was to have an educational activity that was going to be fun," she said. "Each of the items reveal little known facts about each of our dams, so it's also a way to promote the other dams on the river."

Chief Joseph Dam is about 50 river miles downstream from Grand Coulee Dam, Brougher said. (A river mile is a measure of distance in miles along a river from its mouth) It's about an hour and a half drive from Grand Coulee Dam to Rocky Reach Dam, she said.

When people complete the geocaches at Grand Coulee Dam, they get a piece of the overhead power lines that used to carry electricity, she said. Participants must claim their prize during the visitor center's operating hours.

The Grand Coulee Dam visitor center is open from 9 a.m. to 5 p.m. daily, with extended summer hours, said Brougher.

While it is possible to complete the Grand Coulee portion of the challenge year-round, the other two dams are not open in the winter, she said.

"People can get to the geocaches in some areas, but folks can't get their stamps because the visitor centers might not be open," said Brougher.

She said the best time to complete the challenge would be during the summer.

"Most of the participants last year did it in the summer," she said. "Some people only did one or two dams and plan to complete the challenge this season so that's possible as well."

For more information on geocaching at the Grand Coulee Dam, call 509-633-9265.