Yep, looks like depending where you go, its either C&R, or seasonal
East Branch Croton River from Diverting
Reservoir to East Branch Reservoir Trout All year 14" 1 Artificial lures only
West Branch Croton River from Croton Falls
Reservoir to East Branch Croton River Trout April 1 – Sept 30 Catch and release only Artificial lures only
My understanding is that trout are harder to catch in colder streams because of their energy conservation. Hell, I was out on Kensico Sunday afternoon, and caught nothing too. Maybe try a worm and a split shot, if they're bunching up on the bottom to keep warm?