It runs about 3.38 miles (5.4 km) from Roxhill Park north to the Duwamish West Waterway at Elliott Bay.
Salmon, absent for 60 years, began returning without intervention as soon as toxic input was ended and barriers were removed.
Construction of a fish ladder at the north end of the West Seattle Golf Course will allow spawning salmon up along the fairways.
Farther upstream the city has been enlarging and building more storm-detention ponds, recreation areas, and an outdoor-education center at Camp Long.
Three acres of open upland, wetland and wooded space just east of Chief Sealth High School in Westwood is the first daylight of Longfellow Creek.