16,000 Trout Stocked Beneath Ice at Eleven Mile Reservoir

Snow crunches beneath tires as the rigs creep down the North Shore Boat Ramp and prepare to unload their cargo of 16,000 cutbow trout.
Snow and ice covers Eleven Mile Reservoir in South Park
Snow and ice covers Eleven Mile Reservoir in South Park. Video capture by Jerry Neal/CPW.

On a brisk morning in early February, three hatchery trucks from the Mt. Shavano State Fish Hatchery arrive at Eleven Mile State Park. Snow crunches beneath tires as the rigs creep down the North Shore Boat Ramp and prepare to unload their cargo of 16,000 cutbow trout. After spending nearly 15 months confined to hatchery raceways and traveling more than an hour over snow-packed roads, the cutbows face just one final obstacle before their release into Eleven Mile Reservoir: 12-inches of rock-hard ice.

For most states, frozen lakes and freezing temperatures would put hatchery operations and fish-stocking plans “on ice.” Yet, this unique and ambitious effort is all part of Colorado Parks and Wildlife’s Winter Fish-Stocking Program.

Ice-capped Underworld

Over the next hour, the crew from Mt. Shavano unloads a gas ice-auger, canvas tubing and numerous sets of ratchet-straps–all tools of the trade for stocking fish in winter. South Park is famous (although, most anglers would say “infamous”) for its high winds, and Mother Nature lives up to her blustery reputation on this particular morning. Hatchery technicians Bryan Johnson, Dave Karr and Mark Haver battle 50-MPH gusts as they assemble a temporary pipeline from the stocking trucks to a single hole drilled in the ice. With the pipeline connected, Karr lifts a t-shaped lever on top of the truck and the cutbows begin their tubular descent through the ice. Within minutes, the trout begin to explore the vast, ice-capped underworld of Eleven Mile Reservoir.

Hatchery Technician Mark Haver drills through rock-hard ice
Hatchery Technician Mark Haver drills through rock-hard ice at Eleven Mile Reservoir. Video Capture by Jerry Neal/CPW.
auger blade cuts through rock-hard ice at Eleven Mile Reservoir

Although winter might seem like an unlikely time of year to stock Colorado’s high-elevation reservoirs, CPW Hatchery Technician Bryan Johnson says there are some significant advantages to planting fish during the “off” season.

“Winter stocking gives us a great opportunity to increase production at our hatcheries by utilizing timing when, historically, there wasn’t a demand for fish production,” said Johnson. “It also has let us increase diversity by stocking when different fish species are available from the hatchery.”

Located in Salida, the Mt. Shavano State Fish Hatchery stocks between 100,000 to 140,000 trout annually during the winter–usually a combination of Snake River cutthroats, cutbows and rainbow trout, based on the hatchery’s inventory.

Fertile South Park Reservoirs

Currently, Spinney Mountain and Eleven Mile are the only reservoirs in the state that receive fish through the ice, with the later receiving its only annual stockings of trout January through March. Despite the frigid water temperatures, the trout enjoy expedited growth once they are planted in the fertile South Park reservoirs. Johnson says this provides exceptional fishing opportunities for anglers come spring.

“The cutbows and cutthroats are some of the slower-growing fish in a hatchery, taking 14-15 months to reach catchable size of around 10 inches,” said Johnson. “But once stocked into a productive body of water, they seem to thrive. The fish continue to grow under the ice, achieving 13-14 inches in length by the time the reservoirs open to boating in spring.”

Dave Karr lifts a lever on the hatchery truck
Dave Karr lifts a lever on the hatchery truck to release the trout from the storage tank. Video capture by Jerry Neal/CPW.
 A temporary, canvas pipeline transports the fish from the hatchery truck through the ice.
A temporary, canvas pipeline transports the fish from the hatchery truck through the ice. Video capture by Jerry Neal/CPW.

Additionally, Johnson says that stocking in the winter gives the hatchery trout the greatest chance of survival. Both Spinney and Eleven Mile are home to large (as in seriously large) northern pike. The toothy predators tend to feast on trout that are stocked in the spring and summer. Fortunately, pike are more dormant in the winter, which gives the newly planted trout time to settle into their new surroundings instead of being immediately gobbled up.

Winter Fish Stocking Program

Since its inception in 2007, CPW’s Winter Fish Stocking Program has planted more than 740,000 trout in Eleven Mile and Spinney. Johnson attributes the program’s success to good planning and teamwork.

“The winter stocking program is truly a collaborative effort between the parks, our Aquatic Biologist Jeff Spohn and the hatchery staff,” said Johnson. “The park staff is constantly clearing the boat ramps and parking lots of snow to allow continued access to the fish trucks. Everyone works together to make this happen every year.”

CPW’s Winter Stocking Program is proof that neither snow nor wind–or even a foot of ice–can keep the Mt. Shavano Hatchery crew from stocking South Park’s reservoirs. Thanks to these ongoing efforts, Spinney Mountain and Eleven Mile continue to boast some of the best trout fishing in the state.

Did you know?

Based on economic-impact studies, a single catchable-size trout generates $36 to Colorado’s economy and costs approximately $1.20 for CPW’s hatcheries to produce. CPW does not receive general tax dollars. Therefore, fishing-license fees support all statewide hatchery and fish-stocking operations. CPW stocks 90 million fish annually into waters throughout Colorado.


The following video provides an intimate, underwater look into CPW’s Winter Stocking Program at Eleven Mile State Park.

Story and video by Jerry Neal. Neal is the editor for Colorado Outdoors Online and is a media specialist for CPW. 

14 Responses

    1. Toby, Thanks for your question. Here are some of the reasons Spinney closes in the winter:

      Road Maintenance:

      Under a management agreement with the City of Aurora, they are responsible for maintaining the roads in and out of Spinney. These crews are often off-site tending to waterworks far from the park and would be unable to have staff available to ensure that roads would not get drifted in (which happens regularly up there, even with just an inch or two of snow), which could potentially strand a number of visitors for extended periods of time.

      Gold Medal Fishery:

      Spinney Mountain Reservoir is one of three reservoirs in the state with Gold Medal Designation. Even if the road situation was eliminated, there is a lot of concern that people would exploit the resource, over-limiting on trophy-sized fish, or culling them, which would lead to high mortality in winter. We feel the winter closure helps to protect the quality of this fishery.

      Draw-Down in Winter:

      Spinney Mountain Reservoir is typically drawn down throughout the winter, leading to large gaps between the ice and the liquid water in the reservoir. That’s a recipe for disaster if the ice sheet collapsed since it would be extremely hard to extricate oneself from the water if the entire ice sheet collapsed. Aurora supposedly had instances where the air gap between the water and ice was several feet thick. It wouldn’t take much to get the surface ice to collapse on the whole reservoir, posing a huge risk to anglers.


      Staffing is also a concern, as park staff is shared between Spinney and Eleven Mile. As big as Eleven Mile is, we don’t have the staffing to cover both parks in the winter.

  1. Great video and a great job by the Colorado hatcheries. My wife and I were at Mt Shavano hatchery in October with our son and our two grandson’s. We all had an interesting education and especially enjoyed their reaction to the feeding frenzy. Gotta love what they do to keep the species strong

    1. Tom, Thanks for your comment. The CPW’s hatcheries do an amazing job of managing our fisheries. I’m glad you and your grand kids had the chance to tour the Mt. Shavano facility. It’s an experience you’ll never forget!

  2. these fish look like feeder fish in a fish tank, too dumb to know how to hunt for food other than looking for it at the surface of the water… as this is the only knowledge they have from their present life experience. is this the best way to preserve any sort of natural fish populations? there is some good from these stocking programs but could these programs be better managed to increase the reproduction rates versus having to just continually dump thousands of fish into waterways annually

    1. It’s important to note that Colorado does not have wild populations of rainbow trout in lakes and reservoirs. Because of the habitat, there is almost no natural reproduction in stillwaters. In order to provide recreational opportunities for anglers, stocking is required. In addition, the hatchery trout acclimate to their environment very quickly. Within 24 hours, the fish have dispersed and are scattered throughout the reservoir. They begin foraging for food almost immediately, which is why they continue to grow 2 to 3 inches by ice-off. Keep in mind, these fish just survived a 70 mile roadtrip and were dumped into a completely new environment (a frozen lake). However, it’s amazing how quickly they adapt and thrive.

      1. “Colorado does not have wild populations of Rainbow Trout” – could that be because they are not native? I really think CPW should focus more on native species…

  3. Awesome video great job. Very informative thank you for the wonderful job you do. As an avid fisherman I appreciate the work you do.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.


✉ Follow for Updates

Subscribe to Colorado Outdoors Online by Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

More Posts

Translate »