In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.
Q: Passage: By 1960, use of the rail line along Johnson Creek had declined and passenger service was discontinued. By 1990 the City of Portland bought much of the corridor. Working with Metro, it created the Springwater Corridor Trail, a 21-mile (34 km) bicycle and pedestrian rail trail that follows the creek and extends from the Willamette River to Boring. It became part of the 40-Mile Loop, a hiking and biking trail that circles the Portland metropolitan area and intersects with similar trails.Creekside parks include Johnson Creek Park, about 4.5 acres (18,000 m2) of natural areas and paths; the Crystal Springs Rhododendron Garden, along Crystal Springs Creek; Tideman Johnson Natural Area, about 7.2 acres (29,000 m2) of natural areas and paths; Leach Botanical Garden, about 16 acres (65,000 m2), a public garden dedicated to the study of botany and horticulture with an emphasis on plants of the Pacific Northwest; Beggars Tick Wildlife Refuge, a wetland of 20 acres (81,000 m2); Powell Butte Nature Park, about 608 acres (2.46 km2) on an extinct cinder cone volcano, including natural areas and hiking, biking, and equestrian trails; and Gresham's Main City Park, about 18 acres (73,000 m2) including sports fields, picnic areas, and trails.In 2007 Metro bought two parcels of land totaling 102 acres (410,000 m2) for preservation adjacent to Johnson Creek on Clatsop Butte, south of Foster Road near Powell Butte and Portland's Pleasant Valley neighborhood. The purchases cost $10.9 million, drawing on bonds approved by a 2006 ballot measure. They were praised by conservationists but questioned by others who thought Metro had paid too much.
A:
What creek does Springwater Corridor Trail follow?