Commemorate Martin Luther King Jr. Day by helping the Olympia-Thurston County Stream Team with tree planting and maintenance; 10 a.m.-noon Saturday; Woodland Creek Community Park, 6729 Pacific Ave. SE, Lacey; free; streamteam.info/getinvolved/calendar.
The South Sound Area Kayakers are leading a trip down the Skagit River to look for bald eagles; there will be come Class 1+ whitewater; immersion gear will be required because of the cold water; helmets are highly recommended; group will set up a shuttle at 9 a.m. and launch at 10 a.m., Saturday; meet at the boat launch off Cascade Road in Marblemount; ssak.hctc.com.
Explore a Tacoma park during a naturalist-led walk; not recommended for strollers or children under 3; 1 p.m. Saturday; Tacoma Nature Center, 1919 S. Tyler St., Tacoma; free; space is limited and registration is required; do so at metroparkstacoma.org or 253-591-6439.
John Pettit will give a program on NASA’s missions to the moon at the public night event held by the Tacoma Astronomical Society; there will be night sky viewing after the program, weather permitting; 7:30-11 p.m. Saturday; Rainier Building, Pierce College Fort Steilacoom Campus, Lakewood; free; tas-online.org.