The SWRC currently maintains eight subwatersheds within the Santa Rita Experimental Range (SRER), the oldest continuously maintained experimental range in the western United States (est. 1903). Established in 1975, these eight small watersheds are set up as paired watersheds.
Each watershed is instrumented with one recording raingage and one flume. The watersheds range in size from 1.05 ha to 4.01 ha. Four of the watersheds (#1 - 4) are in the shrub-dominated lower portion of the experimental range; the remaining four watersheds (#5 - 8) are located in the grass dominated upper portion of the experimental range.
The Santa Rita Experimental Range is currently administered by the University of Arizona, the SRER serves as a primary research location for members of the SWRC working in cooperation with the University