The presence of cattle at Brownie Spring and Ash Springs in Pahranagat Valley, Nevada, impacted fish populations by causing an increase in ammonia (NH3) and nitrite (NO2) levels, an increase in Pseudomonas aeruginosa and Aeromonas hydrophila, and increased mortality and morbidity. One of the affected fishes, the White River springfish, is listed as endangered by the Department of the Interior. After removal of the cattle from Ash Springs, NH3 and NO2 levels decreased and fish populations increased. At Brownie Spring the NH3 and NO2 levels are chronically elevated, cattle are still present, and the speckled dace population has not recovered.
Taylor, Frances R.; Gillman, Leah A.; and Pedretti, John W.
"Impact of cattle on two isolated fish populations in Pahranagat Valley, Nevada,"
Great Basin Naturalist: Vol. 49
, Article 3.
Available at: http://scholarsarchive.byu.edu/gbn/vol49/iss4/3