Oatka Creek becomes a losing stream about 1.5 miles downstream of Main Street in Le Roy (i.e., its surface water volume decreases as it flows downstream, in this case due to percolation into the ground). During the warmer months, the streambed goes dry downstream of Buttermilk Falls, as all of the stream's water flows through subterranean channels; a similar situation occurs along a section of Clear Creek in Chautauqua County. Substantial inflow from springs in an area known as the "Blue Hole" causes Oatka Creek to resurface near Circular Hill Road, and shortly thereafter, it transforms into a high-quality trout stream (see photos). Further downstream, at Mumford, the quality of the stream is again reinforced by the cold, clear waters of the famed Spring Creek. The result is a trout stream that ranks as one of the finest in New York State.

The lower section of Oatka is a slowly meandering stream that ranges from about 50 to 100 feet in width. It has a gravel, rubble, and slate bottom, though a few sections also have a substantial amount of silt, which is typical of spring-fed streams. The water is usually quite clear, and there is a substantial amount of aquatic vegetation throughout much of its length. Surrounded by woodlands, farms, and parkland, much of the stream has an intact riparian corridor with mature trees and understory, which provide at least some of the stream with shade and streamside cover. And unlike many streams in western New York, the Oatka is doesn't freeze over during a hard winter due to substantial infusions of groundwater and the inflow from Spring Creek, making the stream fishable all year. In many regards, Oatka Creek appears to be an almost ideal trout stream.

Unfortunately, some of the very characteristics that make this a fly fisherman’s dream stream—e.g., long, wide sections that never freeze over, a paucity of in-stream woody debris that can provide shelter to fish (e.g., in Oatka Creek Park), and large numbers of wild trout—also make this stream attractive to piscavores, which have returned in large numbers in many parts of New York. These fish eaters include river otters, osprey, Bald eagles, and diving ducks, especially Common mergansers.

Until the end of the 20^th century, New York's Common mergansers spent winters primarily in the Adirondacks, but in recent years they have expanded their winter range to include most of the state, including Monroe County. During normal winters, these birds feed on the open waters of the embayments of Lake Ontario and larger inland water bodies such as the Finger Lakes, feeding primarily on small fish. Adult Common mergansers, which typically weigh about 2.5 pounds, can eat half their body weight in fish every day. Unfortunately, they seem to be especially fond of 4- to 8-inch trout.

The winters of 2013-14 and 2015-16 were especially harsh in Monroe County, and most of the open waters where the mergansers had been feeding froze over, forcing them to find open water elsewhere. Eventually, they found Oatka Creek and Spring Creek, two spring-fed streams that don't freeze over and are full of merganser food. The resulting decline in the trout populations of these streams, especially in Oatka Creek downstream of the confluence with Spring Creek, was dramatic. The declines in the Oatka Creek Park section and Phillip Garbutt Rod and Club section of Oatka Creek is evident in Figure 3 of DEC Technical Report No. 2 (see Links). While much, if not most, of the decline was due to feasting mergansers, the DEC suspects that other environmental factors were—and still are—at work, which may explain why the trout populations in the Oatka Creek Park and Garbutt Club sections have not fully rebounded.

Predation by mergansers still occurs occasionally on Oatka Creek, though at greatly reduced levels. But the continued presence of these birds and other piscivores may be having a lasting effect on the fishery. Prior to the arrival (or is it return?) of piscivores on New York's streams, the only bird that could predate on trout was the Great blue heron, which is limited to feeding in water no more than about 2.5 feet deep. Mergansers, however, can dive to depths of at least 13 feet and are amazingly fast and agile underwater. Consequently, brown trout are becoming very wary and will often ignore hatches and spinner falls if it means venturing into pools that don't have some significant cover. This reluctance has been noticed by anglers on numerous streams in western New York. For example, see "An Angler’s Impressions of Wiscoy Creek" by the DEC's eminant fisheries biologist and expert fly fisherman Scott Cornett. 

Despite the growing wariness of some brown trout to venture out from cover, Oatka Creek is still a good fly-fishing stream. The nutrient-rich waters of the lower Oatka produce a wide variety of aquatic insects. In addition, most of the lower section is large enough to make casting easy. However, this doesn't necessarily mean that the fishing is easy. The native trout of the Oatka can provide quite a challenge to even the most accomplished angler.

Good fly fishing can be experienced as early as the middle of winter here. Dead-drifted olive and tan scud patterns and a variety of nymphs such as the hare's ear and the red fox squirrel tail worked near the bottom can produce fast action. On warm, sunny winter days, when the water temperature increases slightly, an angler may even be able to find a few trout feeding at the surface on midges.

Scud and nymph patterns work well here into early spring. This is when the fishing really picks up. The middle of April marks the beginning of a progression of good hatches that last into early summer. The first is the famous Hendrickson hatch. Thick hatches of duns can be experienced on the Oatka's fertile waters. The hatch usually occurs in the early afternoon and is often followed by good spinner falls at dusk. This hatch normally lasts through the end of April.

The Hendricksons are followed by the tan caddis hatch in early May. Good action can be encountered throughout the day. Sometimes this hatch is best approached with an emerging caddis fished just below the surface or in the surface film. Caddis action can last well into May and overlap the emergence of the March Brown hatch in the middle of the month and the Gray Fox hatch toward the end of the month. Both of these mayflies normally hatch in the afternoon, although they can begin to emerge in the late morning. However, their emergence on the Oatka can be somewhat sporadic. For this reason, the most consistent action can sometimes be found by dead-drifting nymphs, which represent these mayflies in the morning, prior to the hatch.

The Sulphur hatch, which occurs from the end of May until about the middle of June, may be the highlight of the season. The daily emergence of this majestic mayfly usually triggers good surface activity. The hatch normally begins in the late afternoon and lasts until dusk, and it is usually followed by a spinner fall. The balmy evening temperatures of late spring coupled with fast action make this hatch a joy to fish.

As the season progresses into summer, the fishing gets a little tougher, as the water is normally low and clear at this time. The most productive time to fish the Oatka in the summer is in the early morning while the water is still cool. A good time to try a variety of terrestrials is when the water is low and clear and there is no visible surface activity. Small nymphs also work especially well if there is no surface activity. In addition, good tiny Blue Wing Olive hatches can be experienced in the early summer, and some midge hatches also occur in the summer.

As the season moves into fall, hatches are only sporadic, and terrestrials continue to be a good choice. Streamer patterns and wooly buggers can produce well in the fall, especially when the water has risen and is a little off color. Actually, these patterns work well anytime during the year when these water conditions exist. The Oatka tends to muddy after a downpour. For this reason, it is a good idea to try to get the latest water conditions after there has been a heavy rain.

Trout predominate in the lower section of Oatka Creek from its eruption to the surface near Circular Hill Road downstream to the Genesee Valley Greenway Trail footbridge in Canawaugus Park in Scottsville. By the time the stream has reached Canawaugus Park, its transition to a warm-water stream is well underway. Species commonly found in the Genesee River, which Oatka Creek joins about 1.4 miles downstream of the footbridge, begin to show up in Oatka Creek in increasing numbers. These species include smallmouth bass, walleye, northern pike, and various species of panfish. Note that walleye from the Genesee River make a spawning run up Oatka Creek in the spring, and small numbers of northern pike can be found at least as far upstream as Mumford.         

For more good information on how to fish this amazing stream, see Adam Schroeder's article "Fly-Fishing Tactics for Oatka Creek" under Links.

See also Oatka Creek (Upper Section).

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Links to associated resources (Oatka Creek - Middle Section and Genesee River - Mount Morris to Rochester) will be added soon.