Fly Fishing South Platte River - Above Spinney

Fly fishing South Platte River – Above Spinney means working the combined mainstem in the heart of South Park. It runs from the meeting of the Middle and South Forks roughly five miles east to where the current slows into Spinney Mountain Reservoir, sitting near 8,750 feet the whole way in wide-open high-country grassland. Hartsel, the town you stage from, is a couple of miles above where the reach begins.

Below the confluence the river carries two drainages instead of one, and the channel answers accordingly: a wider bed, longer runs, and holding water with real depth, none of which either fork offers on its own. Elevation loss across the reach is only about a hundred feet, near 13.7 feet per mile, and that modest tilt shapes everything. You get an unbroken sequence of riffles feeding into runs, with no plunge-and-pocket structure and no stagnant flats. Fish the tongue at the head of each run, the seam where fast water shoulders against slow, and the deeper slot at the tailout.

Brown trout and rainbow trout are the residents, and a representative fish measures 12 to 18 inches — a serious class of trout for a channel this narrow. The riffle-run cadence sorts them by conditions: they push up into shallow, oxygenated water when something is emerging and drop back into the troughs when the surface goes quiet. With under five miles in play, covering ground wins. Walk between likely runs and let the river show you where fish have stacked up.

Insect activity follows the snowmelt curve more than the calendar. Midges hold down the cold months and stay relevant year-round in small sizes. Blue-winged olives come in two waves, once in spring before the water rises and again in fall as it settles out, both best on overcast afternoons. As runoff recedes into summer, pale morning duns and yellow sallies get going, and caddis take over the riffles and undercut banks in the evenings. Late summer brings tricos on cool mornings and — this being grass country right to the water's edge — ants and hoppers along the banks through warm afternoons.

Flow decides your trip. Despite reservoirs well upstream on both forks, this reach behaves like a freestone, with a wide spread between the height of runoff and late-season base flow. Somewhere between 25 and 200 cfs is the practical window; peak melt is pushy, stained, and rarely worth the effort. Footing is fair, cobble and gravel with predictable seams, so wading rates moderate rather than technical. Exposure is what catches people out — no timber, no canyon wall, nothing to blunt the wind that rakes this basin, and nothing to break up your outline for fish in thin water. Long leaders, low approaches, layers you can add.

Public access comes from the Badger Basin State Wildlife Area, and it pays to understand what that is before you arrive. Rather than a broad parcel you can roam, it is an easement strung along the banks — public only as far as the corridor reaches, with deeded ranchland pressing in on both sides. It traces the mainstem downstream past Hartsel toward the reservoir, and Spinney Mountain SWA takes over at the bottom end near the inlet. Your entry points are the signed pullouts and information kiosks where US 24 and Colorado 9 come to the river around Hartsel. Anything beyond the marked easement is posted private ground, so carry the boundary in your head and stay tight to the water. Do that, arrive on a falling hydrograph, and this short piece of mainstem gives you a full day of honest trout water.