Shadow Mountain Spillway

They don't have a schedule. They're required to keep Grand Lake height within 1 ft b/c of the fixed boat docks there.
And SM is directly connected to Grand. So when the sum of the input flows into Grand/SM exceed the outflows down the tunnel to Denver, the excess goes over the dam. The Pump Canal keeps it up when the flows are too low, like they are now. They can tweak it a little in anticipation of incoming water, but in general what comes in has to go out.
Higher flows usually start about May 1, but this year has been so cold they've been delayed. With the snow pack this winter, when it does warm up it's going to go from a trickle to a 5000 cfs flow almost overnight, I'm betting.
Check all the flows and you can make a pretty good estimate of daily water flow over the dam.