On May 31, 2004, about 2130 Pacific daylight time, a Cessna 170B, N2915D, veered off the runway, hit a runway light, and ground looped during the landing roll at Auburn Municipal Airport, Auburn, California. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The private pilot, the sole occupant, was not injured; the airplane sustained substantial damage. The personal cross-country flight departed Sutter County Airport, Yuba City, California, about 2100, with the planned destination of Auburn. Visual meteorological conditions prevailed, and a flight plan had not been filed. In a written statement, the pilot reported that he was attempting a three-point landing on runway 25. As the airplane touched down near the approach end of the runway, he noted that the airplane was directly over the runway centerline. During the transition to the landing roll, the airplane began to veer from the centerline, following the natural contours and incline of the runway. The airplane continued to veer to the right and departed the runway surface. The right main landing gear contacted a runway light fixture and the airplane ground looped. During the ground loop, the left main landing gear impacted an embankment, resulting in the left wing contacting the ground. The airplane incurred damage to the left elevator, wing tip, and landing gear. The Airport/ Facility Directory, Southwest U.S., indicated that Auburn runway 25 was 3,700 feet long and 75 feet wide, with a 1.6 percent downsloping runway gradient. During a telephone interview with a National Transportation Safety Board investigator, the pilot reported no preimpact mechanical malfunctions or failures with airplane.