Integrating water quality protection from Cryptosporidium parvum into grazing management plans. Tate, Kenneth^*,1, ¹ Agronomy and Range Science, Davis, CA

ABSTRACT- Traditional grazing management tools can be employed in an integrated approach to effectively reduce risk to water quality from Cryptosporidium parvum shed by cattle on rangeland watersheds. An effective grazing management plan to achieve this water quality protection goal must incorporate site information such as seasonal and spatial patterns of forage and stock water availability relative to waterbodies of concern, as well as regional information such as seasonal C. parvum decay rates within the fecal matrix. Objectives of an effective grazing plan must include: 1) maximize hydrologic transport distance between high risk animals and the waterbody of concern; 2) minimize fecal deposition in high transport risk areas during the runoff season; and 3) capitalize upon natural decay rates of oocysts in feces excreted in the watershed. Results from experiments examining spatial and temporal cattle fecal loading patterns, decay of oocysts, and hydrologic transport of oocysts on California annual rangelands will be presented as the basis for these objectives. Grazing management plans developed for lands adjacent to drinking water reservoirs in the region will be presented to illustrate application of basic grazing management tools to achieve these management objectives. Strategic implementation of vegetative buffers and herd management practices such as calving season duration as supplementary water quality protection practices will be discussed.

KEY WORDS: drinking water, water quality, annual rangeland