April 18, 2026

The Spot

Montgomery Reservoir sits at 10,900 feet in Park County, Colorado. The river inlet is where the fish are. I’ve been coming here since I was a kid, the cabin my grandfather built is about a half mile up the road.

Rainbow trout are the main catch. The chart on the next slide shows typical length-to-weight data for rainbows in high-altitude Colorado lakes. Pretty useful for knowing when you’ve got a keeper.

Length vs. Weight

The Rule of Thumb

  • Under 12 inches — put it back
  • 14–18 inches — the sweet spot
  • Over 20 inches — that’s a good day

Most keepers at Montgomery run 13–16 inches in summer. Spring and fall can surprise you.