Current regulations give the following numbers for reporting poaching activity:
Incident Hotine.....1-800-477-6224 (M-F, 8am-5am)

For reports outside the hours above, call the nearest State Patrol Office. The Seattle region phone number is (206) 464-6610. Other WSP numbers are on page 7 in the regs, or listed in the gov. section of the phone book.

If the incident is ongoing, you might want to report it to both agencies, and hope someone responds in time to catch the culprits in the act. It doesn't "take a village" to cause poachers some grief, just an irate individual with a phone. I've made the call twice, and in both cases, the violators were cited.