YUPON CREEK. Yupon Creek rises just above the flood control impoundment formed by Spillway 351 eight miles northwest of Columbus in north central Colorado County (at 29°49' N, 96°40' W) and flows for seven miles, crossing State Highway 71 at Hillcrest, into an area of Rocky Creek heavily strip-mined for gravel (at 29°44' N, 96°36' W). The soils through which it flows consist of a deep, pale brown, loamy sand surface layer over a gray, sandy clay subsoil. Below Highway 71 Yupon Creek enters the floodplain of the Colorado River, where the soils contain deep layers of silty loam over deposits of gravel. Vegetation along the creek's upper reaches consists of a mixture of oak and cedar with a dense understory of yaupon, which gives the stream its name. This area is used primarily as unimproved pasture for cattle and as wildlife habitat. Improved lands near the mouth produce good crops of hay and excellent pasture, but commercial gravel extraction, which began on a large scale during the 1940s, has produced an extremely uneven landscape of spoil banks.