Just east of Limon, Colorado, Interstate 70 climbs onto the steep, High Plains escarpment, where a large wind farm extends off to the north. At the crest of that ridge, one leaves the Arkansas River watershed and enters that of the Missouri River.
More specifically, the Interstate begins to cross the upper watershed of the Republican River, a secondary tributary of the Missouri. Rising SSW of Flagler, Colorado, the river's main channel crosses under the highway just east of that town, flowing northeastward toward Nebraska. Receiving seasonal flow from numerous streams of northeast Colorado, northwest Kansas and southernmost Nebraska, the Republican passes through McCook, Nebraska before winding eastward just north of the Kansas border. Finally dipping to the southeast, the river passes through Milford Lake and then courses along the north side of Junction City, Kansas, where it merges with the Smoky Hill River to form the Kansas River; the latter flows into the Missouri River at Kansas City.
Though it is a major river of the High Plains, flowing for more than 450 miles and draining a relatively large watershed, the Republican, like many other streams of the Great Plains, is unknown to the traveler who uses our Interstates and primary highways. Its upper tributaries (and even its upper main channel) are dry for much of the year, their course marked only by the shrubs and trees that cluster along their banks. But for wildlife of the High Plains, such streams offer vital riverine habitat for nesting, denning, feeding and escaping the harsh weather of that vast, semiarid ecosystem.
