Found the term "action stage" days ago when looking up Kenai water level on the Alaska River Forecast Center (using the sticky on the Rafting forum - very handy). The Kenai at Cooper Landing was running just under 12 ft, which was the "action stage" threshold. Looks like we will get a short break from the rains if clear skies hold today (Sat, 8/7).
The NWS website included a definition (below)for "action stage". In practical terms, it sounds like they mean folks along river might need to take action in response to high water levels; property owners might need to prepare for flooding/erosion. For river campers/rafters, as you posted, consider alternatives to campsites that are usually dry, and be prepared for high water conditions, brisk flows, etc.
Action Stage - the stage which, when reached by a rising stream, represents the level where the NWS or a partner/user needs to take some type of mitigation action in preparation for possible significant hydrologic activity. The type of action taken varies for each gage location. Gage data should be closely monitored by any affected people if the stage is above action stage.
Thanks for posting this.
Helpful and informative post, thanks. Hope all the rivers return back to normal sometime soon. Kind of a bummer beaching the raft in the alders!