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A Trip To Zimmerman

Posted by allynkratz on September 23, 2015 in Blog Post, Slideshow

Summer is ending, as we get ever closer to fall and winter our minds start to turn away from fishing toward the ski slopes. As summer is not quite over yet I think a couple more trips could be in order. Zimmerman Lake is a high mountain body of water nestled in a mountain bowl. It is surrounded by acres of National Forest, rimmed by scree fields that transition into craggy peaks that seem to kiss the clouds. The beauty of the place is not its most redeeming character though. Zimmerman is home to the only population of stocked greenback cutthroat trout in the nation. These fish represent the first step in greenback restoration across the state.

Zimmerman Lake, Northeast of Rocky Mountain National Park

Zimmerman Lake, Northeast of Rocky Mountain National Park

The greenbacks in Zimmerman are part of ground breaking genetic science that has never been seen before in the trout world. Right now the fish in Zimmerman are being weeded out by nature, any deformities, abnormalities or sickened fish will eventually die. This leaves only the fittest fish, these will be retaken and their genes will be analyzed to ensure breeding in captivity is as effective as possible. The genetic work surrounding the greenbacks is groundbreaking, by selectively breeding the fish biologists are attempting to steer greenbacks away from a genetic bottleneck.

Zimmerman Lake, August 2015

Zimmerman Lake, August 2015

There is one inflow stream coming into Zimmerman, it is not large but it does offer adequate habitat for spawning trout. In the spring greenbacks make their way up the stream to spawn, they return to the lake after eggs have been fertilized and fatten up the rest of the summer. Depending on the snow pack emerging fry swim down into the lake from mid October to November. By this time the summer has come to a close and food has become scarce, adult greenbacks in Zimmerman are eager for a free meal. When the fry enter the lake most, if not all, are eaten. The tiny inflow stream that brought the fry life delivers them as dinner to a waiting crowd of hungry mature greenbacks.

Fishing for these mature greenbacks is legal and easy. Zimmerman Lake is about a two and one half hour drive from Denver followed by a one mile hike from the parking lot. When at the lake pick up trash, fish with crimped barbs and respect other lake goers. Some effective flies are small streamers, small dark nymphs fished with an indicator, and the occasional hopper. It is important to fill out a catch card on the way out as these give Colorado Parks and Wildlife information on the usage of the area. Enjoy the fishing and the fish at Zimmerman because both are one of a kind.

A Zimmerman Lake greenback fooled by a nymph.

A Zimmerman Lake greenback fooled by a nymph.

Be sure to follow the greenbacks journey by visiting CTU’s Greenback Recovery Efforts page at


This post was written by Colton Gully under a 2015 Colorado TU Leo Gomolchak Conservation Grant Program (GOMO grant). The grant is named for Leo Gomolchak, a tireless advocate for cold water conservation in Colorado and a leader in CTU, who passed away in 2007.  He also was one of the founding members of CMCTU. This article was originally posted at website on September 8th, 2015.

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