A major conservation practice in the Upper Snake-Rock (USR) watershed is the conversion from furrow to sprinkler irrigation system. We compared the effect of irrigation system on water quality and quantity at the microwatershed scale (154-682 ha). Six microwatersheds were identified and monitored having 7 to 60% sprinkler irrigation and the remaining surface or furrow irrigation. Other agricultural land uses, cropping practices and soils were similar among watersheds. Water quality and quantity entering and exiting each microwatershed was measured with automated samplers during the irrigation season. Water samples were analyzed for concentrations and loads of total sediment; dissolved P, K, Ca, Mg, Na, NO3-N, Cl and NH4-N; and sediment associated P, Ca, Mg, K, and Na. This information was related to frequency and distribution of irrigation systems, conservation practices, cropping practices and other microwatershed characteristics. Preliminary results of microwatershed delineation, and historical cropping and conservation practices compared with microwatershed water quality components will be discussed, as well as the suitability of existing watershed models to predict water quality changes for irrigated agriculture.