Sounds like there is a lot of momentum behind this and it might be easier to deflect than to stop unless the weather is like today. Celebrating the 100th probably is a huge deal for the agency, which certainly have manages a lot of great habitat for birds. And they people behind this particular event have put time, money, and effort into planning and executing it and probably will be reluctant to abandon it.
Is there a way this could be done and disturbance minimized? What if they lit up the falls from right below so the gorge itself wasn't illuminated, and instead of hiking up the gorge they centered the celebration on the overlook rather than hiking the gorge hike? Maybe there's a local bird-loving food truck or caterer who would be willing to offer food at a discount to the parks for the three nights up at the visitor center by the overlook?
Is there someone on the list with contacts at the Regional State Park office or at the Chamber who could sound them out on whether they are open to alternatives? Does the bird club have any programming it runs in partnership with any of the local state parks? We could try to shut this down but there's a good chance that would fail and, whether or not it did, trying to shut it down entirely will piss off a lot people which might not be good for birds (or even birders) in the long run. Note the Chamber of Commerce seems to be running the hikes so anyone on the list who is a member might want to gently explain the issue to Jennifer Tavares, who seems like a decent person. Not sure if Fred Bonn is still the Regional Director of State Parks but he has been flexible in the past when approached given actual evidence and alternatives - but whoever approaches him should be prepared with published evidence or personal reports by someone (maybe Tim G) who is an acknowledged expert on peregrines and can show that the light show is going to disturb the peregrines. Keep in mind that these folks know peregrines nest on urban bridges and buildings that are lit at night so they will need to know why this is different.
