Question: When did the namesake of Pre's Trail, located on the north side of the Willamette River in Eugene, Oregon, United States, popularly referred to as "Track Town USA", is a four-mile-long running and walking trail named after a heralded University of Oregon athlete die?

Context paragraphs:
Pre's Trail: Pre's Trail, located on the north side of the Willamette River in Eugene, Oregon, United States, popularly referred to as "Track Town USA", is a four-mile-long running and walking trail named after heralded University of Oregon athlete Steve Prefontaine.  The woodchip-and-bark trail features riparian scenery, including grasslands, duck ponds, and woods, as well as guide signs with trail maps at each of three primary trailheads.  Near downtown Eugene, in Alton Baker Park, Pre's Trail is part of an extensive network of running trails in and around the university town and neighboring Springfield.

West Side CSO Tunnel: The West Side Combined Sewer Overflow Tunnel (also West Side Big Pipe) is a tunnel in Portland, Oregon, United States.  It receives and stores overflow from the combined sewer system before it can reach the Willamette River.  The main tunnel is 14 ft in diameter and 3.5 mi long for a capacity of 2850000 ft3 and connects to dozens of smaller sewer overflow interceptors along the west side of the Willamette River.

Coast Fork Willamette River: The Coast Fork Willamette River is one of two forks that unite to form the Willamette River in western Oregon in the United States.  It is about 40 mi long, draining an area of the mountains at the south end of the Willamette Valley south of Eugene.

Steve Prefontaine: Steve Roland "Pre" Prefontaine (January 25, 1951 – May 30, 1975) was an American middle and long-distance runner who competed in the 1972 Olympics.  Prefontaine once held the American record in seven different distance track events from the 2,000 meters to the 10,000 meters.  Prefontaine died in May 1975 at the age of 24 in an automobile accident in Eugene, Oregon.

Wayne Lyman Morse United States Courthouse: The Wayne Lyman Morse United States Courthouse is a federal courthouse located in Eugene, Oregon.  Completed in 2006, it serves the District of Oregon as part of the Ninth Judicial Circuit.  The courthouse is named in honor of former U.S. Senator Wayne Morse who represented Oregon for 24 years in the Senate and was a Eugene area resident.  Located in downtown Eugene, the building overlooks the Willamette River.

Spring Valley (Oregon): Spring Valley is a valley in Polk County, Oregon, United States, situated north and east of the Eola Hills and west of the Willamette River.  It corresponds roughly to the drainage of Spring Valley Creek.  Populated places in Spring Valley include Zena and Lincoln.  Oregon Route 221 passes along the east side of the valley, next to the Willamette River.

Willamette River: The Willamette River ( ) is a major tributary of the Columbia River, accounting for 12 to 15 percent of the Columbia's flow.  The Willamette's main stem is 187 mi long, lying entirely in northwestern Oregon in the United States.  Flowing northward between the Oregon Coast Range and the Cascade Range, the river and its tributaries form the Willamette Valley, a basin that contains two-thirds of Oregon's population, including the state capital, Salem, and the state's largest city, Portland, which surrounds the Willamette's mouth at the Columbia.

Coryell Pass: Coryell Pass is a gap located near Eugene in Lane County, Oregon, United States, near the confluence of the Coast Fork and Middle Fork of the Willamette River.  The gap is formed by the river between Eugene's South Hills and Springfield's Quarry Butte.  The pass is commemorated by a brass marker located on Franklin Boulevard, on what was formerly the route of Pacific Highway.  The marker, which was placed by the Daughters of the American Revolution (D.A.R.), reads "Coryell Pass, Oregon Trail, 1846, Erected by Oregon Lewis and Clark Chapter D.A.R., 1917".  The pass was on the southern route of the Oregon Trail blazed by Jesse Applegate and known as the Applegate Trail.

Oregon Ducks: The Oregon Ducks are the athletic teams that represent the University of Oregon in Eugene, Oregon.  The Ducks compete at the National Collegiate Athletic Association (NCAA) Division I level as a member of the Pac-12 Conference.  With eighteen varsity teams, Oregon is best known for its American football team and track and field program, which has helped Eugene gain a reputation as "Track Town, USA".  Oregon's main rivalries are with the Oregon State Beavers (the Civil War) and the Washington Huskies.

Ferry Street Bridge (Eugene, Oregon): The Ferry Street Bridge is a bridge that spans the Willamette River in Eugene, Oregon, United States.  It is located near downtown Eugene, where the city's founder Eugene Skinner once operated a ferry service.  The bridge is at Willamette river mile 182.2, and is a block west of the north terminus of the actual Ferry Street.  The neighborhood immediately north of the Willamette River near the bridge is often called the "Ferry Street Bridge area."

Supporting paragraphs: Pre's Trail Steve Prefontaine
Answer: May 1975