The 52nd running of the Tevis Cup Endurance Ride will start Aug. 5 with one less obstacle.

A cave-in of an abandoned mine shaft opened up under a section of the Western States Trail near a footbridge along the route last month. The cave-in created a deep hole and threatened to cause a detour.

But Tahoe National Forest officials worked with the state Department of Conservation's abandoned mine lands unit to close the hole and allow horse riders, as well as other trail users, to continue to use the trail. The hole was located at near the bottom of El Dorado Canyon, between Michigan Bluff and the abandoned mining town of Deadwood, east of Foresthill.

When first discovered, Western States Trail Foundation volunteers flagged the trail and the site of the collapse to warn users of the potential danger.

Then Tahoe National Forest abandoned mine specialist Rick Weaver worked with the mine reclamation office to conduct a field review as quickly as possible.

The Department of Conservation provided materials and personnel to fill the hole.

District Ranger Jan Cutts described the effort as an "awesome response."

In one day, the group poured 17 cubic yards of material - the equivalent of a 10-foot-by-15-foot room - into the hole. At the end of the day, there was little evidence the hole ever existed, Cutts said.

"This is yet another great collaborative effort that helps the Forest Service care for the land and serve the people," Cutts said.

Cy Oggins, manager of the Department of Conservation's abandoned mine lands unit, said there are an estimated 47,000 abandoned mines in California. The majority pose a physical hazard to the public, he said.

"The department places a high priority on remediating abandoned mines that are located near population centers, campgrounds or trails, as in this case," Oggins said.

The Journal's Gus Thomson can be reached at gust@goldcountrymedia.com.