The Mimbres is a 91-mile-long (146 km) river in southwestern New Mexico. It forms from snow pack and runoff on the south-western slopes of the Black Range at 33°06′58″N 107°51′04″W / 33.11611°N 107.85111°W in Grant County. It flows southward into a small endorheic basin east of Deming, New Mexico in Luna County. The uplands watershed are administered by the US Forest Service, while the land in the Mimbres Valley is mostly privately owned. The upper reaches of the river are perennial. The river flows south from the Black Range and the surface flow of the river dissipates in the desert north of Deming, but the river bed and storm drainage continue eastward, any permanent flow remaining underground. The Mimbres River Basin has an area of about 13,000 km² (5,140 mi²) and extends slightly int