While northeasterly, the Bouse Wash drainage borders the Bill Williams River Drainage, (almost a de facto separation line of the Mojave Desert northwest and the Sonoran Desert south and east), the Tyson Wash drains the extensive 75-mile (120 km) long north-south La Posa Plain.

Quartzsite, Arizona and four mountain ranges to the south, including western regions of the Kofa National Wildlife Refuge, all drain north into Tyson Wash.

The La Posa Plain turns northwest to meet the Colorado River, and the south of the Parker Valley; Tyson Wash remains to the left (southwest) of the plain's direction and enters land abutting the southeast of the Colorado River Indian Reservation.

The northern region of the wash is accessed by dirt road west of AZ Route 95; the route is about 25 miles (40 km) long and ends at the southern area of the Colorado River Indian Reservation, 35 miles (56 km) north of Ehrenberg, Arizona.

The three plain region is bordered on the northeast by parallel mountain ranges and valleys referred to as the Maria fold and thrust belt.