I had been under the misimpression that river closures were based solely on the water reaching a certain temperature. Apparently water temperature is not the only criteria, and the decisions are based on judgements being made within the FWP on various factors, including water levels within the individual streams, that would be stressful to trout.
There was a lengthy front page article in yesterday's Livingston newspaper discussing this subject that included statements made by FWP Commission Chairman Dan Vermillion and others. Apparently I was not alone in not understanding what triggered these hoot owl restrictions as John Bailey, owner of Dan Bailey's Fly Shop in Livingston, was quoted in the article as also not fully understanding FWP's policy.
FWP's drought policy calls for angling restrictions when flows drop below critical levels for fish, when water quality is diminished, or when water temperatures increase to levels that stress fish for three consecutive days.
In summary, even if water temperatures drop, angling restrictions could remain in place for awhile until water flows increase. Since water levels typically do not increase at this time of the year, these restrictions could remain in place for weeks or even longer on some streams.