Rio Del Lago 100 Mile + 50K Endurance Runs 2026

Rio Del Lago is an autumn trail-running series at Granite Bay and Folsom Lake, California, featuring a 100-mile race and a 50K. The 100-mile race covers 160.9 kilometers and climbs 4,267 meters, presenting a true ultramarathon challenge rather than a flat speed course. Altra presents the event, with the 100-miler as the main race. The course follows rolling, historic trails around Folsom Lake and Lake Natoma, with sufficient climbing to reward steady pacing. The field includes strong California trail runners and ultrarunners from across the U.S. Recent results indicate the competition level: Lindsey Dwyer of Larkspur won the 100-mile race outright in 15:51:35, ahead of all other competitors, while Kyle Roberts won the men’s race in 16:58:35. The 50K also attracts fast runners, with winning times typically between four and four and a half hours on the same rolling terrain.