From the WDFW Elwha Chinook HGMP:

http://wdfw.wa.gov/publications/01561/wdfw01561.pdf

Date program started (years in operation), or is expected to start-
Chinook releases into the Elwha River started in 1914, but consistent annual releases did not occur until 1953. The Elwha Channel, built in 1974, was originally designed to be a spawning channel, but because of difficulties in attracting adults onto the site, it was modified for use as rearing ponds.

For recent year origin estimates, see table on page 15.

Also,

3.4) Relationship to habitat protection and recovery strategies-
Elwha Hatchery Chinook salmon are included as part of the listed Puget Sound Chinook ESU. The program currently represents the vast majority of the production in the basin. As the EFRP progresses with dam removal and into the Recolonization phase, the hatchery program will be an integral part of the restoration effort, supplying adult Chinook salmon to utilize newly accessible and recovering habitat both above historic dam sites and in the lower reach of the river.