September 21, 2017
By Ken McCoy
In the early 1820s, a group of fur traders heading from St. Louis, Missouri to Green River, Wyoming, decided to make camp just west of Fort Collins, Colorado, in present-day Bellvue. That night a huge snowstorm came over the mountains and socked them in. Determined to deliver their product, the wagon master instructed the crew to dig a pit and hide all the nonessentials. Turns out, most of the nonessentials were barrels of gunpowder. So, they hid the powder along the shores of a river that came to be known as the Cache la Poudre, an old French term meaning "hide the powder."
The Poudre (pronounced "pooder"), as it is known to locals, has its origins near the Continental Divide in Rocky Mountain National Park. This freestone river wastes no time dropping 7,000 feet in elevation before reaching the mouth of Poudre Canyon.
After reaching the Front Range, the Poudre continues to flow east prior to meeting up with the South Platte River and heading across the plains to Nebraska. Fly fishers target areas in the 80-mile stretch between the headwaters and the city of Fort Collins. Most of the fishable water is in Poudre Canyon where high peaks, steep granite walls, and fast whitewater runs can make any visitor seem universally insignificant.
The Cache la Poudre, its tributaries, and the various nearby high mountain lakes are home to wild browns, brookies, rainbows, cuttbows, and two different subspecies of cutthroat trout greenback and Colorado River.
Seventy-six miles of the Cache la Poudre River was designated as both Wild & Scenic by Congress in 1986, and it remains Colorado's only Wild & Scenic River. Its carefully managed wild trout waters allow trout up and down the Poudre Canyon to flourish.
Colorado is well known for its diverse fly-fishing destinations. There are approximately 107,403 miles of river throughout Colorado with lots of options for slinging flies and chasing trout. However, less than 1 percent of those waters can boast a national designation like the Cache la Poudre. Statistically speaking, it's a special place, and I hope it stays that way.
I like to think those fur trappers came back to the Poudre to find their stash untouched, and discover the beauty of the river on a quiet summer afternoon. I also like to think they spent a little time casting flies and catching native trout along its willow-lined shores.
In the Poudre Canyon
Poudre Canyon is the quintessential Rocky Mountain playground with a myriad of outdoor activities. Between June and August, most of the nonfishing action occurs downstream of The Mishawaka, a popular restaurant, bar, and outdoor music venue. With only a few exceptions, fly fishing is best upstream from "The Mish" where crowds thin dramatically. Aside from the occasional unseasonably warm spell, after Labor Day the entire canyon is fairly wide open to fly fishers.
After a short drive up the canyon, you'll find the North Fork of the Poudre and the Gateway Natural Area. The North Fork flows out of Seaman Reservoir and trickles along, cutting through a serene valley before joining up with the main Poudre River.
The hike along the North Fork is easy, generally following a dirt road to Seaman Reservoir. This mile-long stretch of catch-and-release only water holds some surprisingly large rainbows and browns given the meager size of their habitat. Sixteen-inch browns are not uncommon, although 10- to 12-inch rainbows are plentiful.
In the winter, the North Fork gives fly fishers an opportunity to keep their skills sharp while other local waters are iced up. With average yearly flows of only 60 cubic feet per second, this stretch of the North Fork of the Cache la Poudre also offers the chance to use lighter tackle than on the main river. Apart from an abandoned beaver dam that has created a model willow-lined pool, the North Fork is no more than 30 feet across at any given point. A 1-weight rod isn't out of the question, but most locals use the mini tailwater to dust off the 3-weight fiberglass rod that seems to mysteriously find its way to the back of the closet.
After leaving Gateway Natural Area, your 5-weight rod loaded with weight-forward fly line and 5X tippet will be your most dependable companion. Upstream you can expect higher flows, wind, bigger water, and a few steep climbs once you've spotted a run you can't pass up.
Most sections are easily accessible, and multiple roadside turnouts provide adequate parking. The water flowing through the section known as The Narrows will give even the most adventurous climber pause, but the rest of the canyon water is easy to access on foot. Access points including Ansel Watrous, Diamond Rock, and the wide open valley just downstream from the Poudre River Fish Hatchery give fly fishers a number of different choices to find their own water.
Hatches & Flies
The Poudre River is a vigorous freestone river and as in other healthy watersheds across the country, stoneflies are plentiful. Pat's Rubber Legs (aka Girdle Bug) is one pattern that fishes great up and down the Poudre.
Cicadas are also quite common through the summer, and patterns like Gypsy King and the Green River Cicada, in sizes 10 or larger, treat you right. When the wind kicks up and tight loops are harder to come by, reducing your hook size and profile is important. Have a box full of Prince Nymphs and Pheasant Tails when fishing the Poudre on windy days.
A Beadhead Prince trailed by a Soft-hackle Pheasant Tail can be a deadly combo at the heads of deep pools all along the Poudre.
Aside from midges, streamers, and all the fun terrestrial patterns that make our eyes light up, there are only a handful of important hatches on the Poudre. The first, and subsequently the last, major hatch is the Blue-winged Olive. This mayfly makes appearances in the spring, and then once again in the fall to close out the fishing season. Hare's Ears, Barr Emergers, and the standard Parachute Adams work well at imitating the various life stages of this Baetis species. Another mayfly, the Western Green Drake, makes appearances sporadically starting in mid-June until August. However, if runoff is particularly high in May and June, Green Drakes will be nonexistent. A standard Green Drake dry works well on the surface, and swinging the classic Greenwell wet fly at the tails of large pools can induce all sorts of adrenaline.
Yellow Sallies and Little Yellow Sallies start to take flight in late May, and you may find them as late as August. Beadhead Yellow Sally Poxybacks are great nymph patterns when trout are feeding deep. Golden Stoneflies are prolific throughout the canyon and can be on the end of your line year round. An Improved Sofa Pillow trailed by a Prince Nymph or Pheasant Tail is always a dynamic duo in the canyon. Kaufmann's Stone followed by Rick Takahashi's Go2 Prince Nymph is also a great rig when the water is up and the fish are down.
In 2014, Colorado Parks & Wildlife (CPW) biologists released 1,200 greenback cutthroat into Lake Zimmerman, approximately 66 miles west of Fort Collins on Highway 14. In anticipation of the release, and to avoid crossbreeding with brook trout and rainbows, CPW officials poisoned Lake Zimmerman with rotenone.
The trailhead to Zimmerman Lake is located just off Highway 14. A steep but short one-mile hike gets you to the shores of Zimmerman. On the west side, the slow rise of the lake bottom allows wading fly fishers to separate from the pine-lined shores. Fishing a dry-dropper rig in these shallows produces well. Adult midges, Elk-hair Caddis, and Adams in sizes 16 or smaller, trailed by an emerging pattern similar to Barr's Emerger or a beadhead Serendipity will bring strikes. Although they are small, it's a privilege to fish for, and catch, these native greenback cutthroat trout.
Just a few miles up the canyon, on the west side of Cameron Pass, Lake Agnes is nestled above the treeline among 12,000-foot peaks. The trailhead for Lake Agnes is a short (but bumpy) drive from the highway. Once on foot, the trail up to the lake is short, but the steep incline can easily take your breath away at this altitude. Fisherman's legend has it that the bottom of this lake has never been touched. There is speculation as to its depth but nothing to confirm the actual facts. If you're feeling confident in both your lungs and your quadriceps, dragging streamers around Lake Agnes in a float tube is killer.
If you head to Lake Agnes to chase Colorado River cutthroat, a small box of flies and a 5-weight rod is all you'll need. Cutties in Agnes slam cicada patterns and other large drys with reckless abandon. Hang a Craven's Juju Baetis 18 inches under a terrestrial like a Super Beetle or a Parachute Hopper and you should have plenty of success.
Along the more shallow northern shore, cutthroat sip insects from the top within view of passing hikers. You may have luck casting small Adams or caddis patterns directly down the shoreline, keeping to the shore side of the shelf that typically juts out four to five feet before dropping dramatically into the depths. Fish like to cruise these shelves, surfacing now and again to take whatever they can find on the surface.
Due to the high elevation, the window of opportunity for Lake Agnes is fairly small. Snow and ice from the northern slopes (including the trail) doesn't finally melt off until late July. The end of August and beginning of September are perfect but the weather can be unpredictable. The snow up here starts to fly again toward the beginning of October.
The Cache la Poudre cuts directly through the heart of Fort Collins. A number of different access points make fishing in town extremely convenient. If you're unsure where to fish, what to use, or simply want some friendly fish talk to get your juices flowing, stop in at St. Peter's Fly Shop for some expert advice.
The staff at St. Pete's spends a lot of time both in the canyon and fishing the waters through town. The Poudre River Trail, a popular urban biking, running, and walking trail, follows the Poudre through Fort Collins, so unless you're braving the cold and fishing offseason, be prepared for a fair amount nonfishing traffic.
The recently completed Shields Street Bridge in the northwest part of town provides convenient access to some excellent runs that hold browns up to 16 inches.
Just upstream from the bridge and parking area, the northern bank has excellent cuts and old oak tree root overgrowth, providing perfect ambush lairs for aggressive browns. In these locations, dead-drifting Mayer's Mini Leech along the far bank produces positive results. Using a strip-and-give technique with a small Bunny Leech pattern also works well when you know fish are out in open water.
The fall months bring outstanding dry-fly fishing opportunities in town. Adams and Blue-winged Olives in sizes 18 or smaller will usually solve the problem of finicky rising brown trout. Early in the fall season, ants and beetles falling from the mature foliage make for exciting surface fishing as well.
Downstream from the Shields Street Bridge, a number of flow-control structures pump extra oxygen into the water, making the areas directly downstream a smorgasbord for feeding trout. Cast directly into the churning water and allow your rig to dead-drift naturally into the feeding areas below.
Farther downstream near Lee Martinez Park, long slow flats allow trout to cruise unabated, sipping bugs from the surface and devouring subsurface emerging bugs. The browns on these flats tend to be a bit smaller than the ones hiding in the cutbanks, but the numbers are significantly greater.
A handful of choke points in the Salyer Natural Area have created deep pools where trout stack up and compete for food funneling through plunge pools. Coupled with textbook cutbanks, created by decaying tree roots and eroding soil, trout have everything they need to thrive.
Although your nymph-rig depth should vary depending on the water levels, these urban locations fish well in both low flows as well as during runoff when the banks are swollen with ice melt headed for agriculture fields on the eastern plains.
As the Poudre continues to flow east through town, the water temperature rises. By the time it has reached Timberline Road, the ecology has changed dramatically. The river and holding ponds east of Timberline are suited better for warmwater species like bluegill and smallmouth bass rather than the coldwater-dependent trout.
Ken McCoy, a Northern Colorado native and outdoor nerd, is a freelance writer, technologist, and guide. He is a contributing author of The Water Holds No Scars: Fly Fishing Stories of Rivers and Rejuvenation (TulipTree Publishing, 2015).