Forest fires in the American River Canyons forced organizers to cancel another of the Endurance Capital of the World’s signature events Wednesday.

The Western States Trail Ride, also known as Tevis Cup was called off after race officials deemed conditions for the 100-mile trail ride to be unsafe. The ride was scheduled for July 19 but was canceled for the first time in history.

The main factor in the decision was the access to Foresthill Divide Road, which will remain closed indefinitely.

“The Foresthill Divide Road is not going to be open next week and it might not be open for two more weeks and that’s how we normally go up and back,” Tevis Cup ride director Mike Pickett said Wednesday afternoon. “The road being closed caused a logistical and a safety issue in our minds. No. 2, the air quality puts the horses and the riders at risk. We really have to think about the safety of the horses, the riders, 800 volunteers and all the crews.”

The 54th edition of the Tevis Cup will have to wait until 2009. The Western States Endurance Run was canceled last month due to fires in the region and the resulting poor air quality.

The Tevis Cup ride begins at Robie Park in Truckee. Riders follow the Western States Trail 100 miles, finishing at the Gold Country Fairgrounds. There is a 24-hour cutoff for riders to finish.

Pickett and several other ride organizers visited Robinson Flat Wednesday to evaluate conditions and accessibility to the ride’s first major aid station. Pickett consulted with Western States Trail Foundation president Tom Christofk and the group determined that canceling the ride was the right move for all parties involved.

“I’ve put a lot of effort, along with a lot of other folks, in planning (Tevis Cup) over the last year,” Pickett said. “But we had laid out a game plan for our decision making process and our risk assessment and this was one of those days that we were making that assessment. It’s sad. People made a lot of plans based around that ride date, but there’s no point in putting people and horses at risk.”

The Tevis Cup ride’s Web site notified visitors of the cancellation Wednesday afternoon while organizers were busy Wednesday contacting the 148 registered riders to notify them.

Many of the horses being ridden are already in the area. Greg Fellers, who serves as the head veterinarian for the ride, said the short-term and long-term affects of the poor air quality on the participants were other factors in the cancellation of the ride.

“Air quality is the No. 1 issue for me and the No. 2 issue is the danger of being trapped somewhere, unable to get out,” Fellers said. “The air quality issue is kind of complicated because we don’t know exactly what’s happening to us after breathing this stuff for three weeks. I had concerns for what the air quality would be on the day the ride was supposed to happen.”