Looking for explanation of 'hatch' on the StVrain
Two weeks ago I was fishing the St.Vrain in WildBasin in RMNP - just below the bridge near the horse trailer lot. I'm a flatlander from Iowa who only gets into the mountains for a week a year.I'd like someone to educate me on the 'hatch' activity that went on for about 2hrs that afternoon.There was a rectangular window of sunlight reaching from the bridge downstream for 75ft or so, down the middle of the river. There was a 'conveyor belt' of small grey insects that were flying upstream at an altitude of 1ft above the water. When they reached the shadow of the bridge they pulled up, did a nice tight 180 turn and then flew downstream at an altitude of 1inch, sometimes touching down - and when they got to the other end of the sunlight they turned and came back up stream. There were thousands and thousands. It was a constant stream that just went on and on.And lots of surface trout activity. When I finally got the right fly on (small, grey 'mosquito') I had 4 good takes in 30 minutes.The most fun I've had on a mountain stream for a couple of years.