DETECTION AND IDENTIFICATION OF CRYPTOSPORIDIUM IN THE RIO GRANDE BASIN PROJECT NUMBER: W-00-1 MORTEZA ABBASZADEGAN, ARIZONA STATE UNIVERSITY HODON RYU, ARIZONA STATE UNIVERSITY ABSAR ALUM, ARIZONA STATE UNIVERSITY INTRODUCTION Waterways have traditionally been a hub for the development of human civilizations. The Rio Grande River is one of the longest rivers in the United States. It starts in Colorado, passes through New Mexico and forms the border between Texas and the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas before continuing to the Gulf of Mexico, reaching a length of 1,960 miles. Irrigation is the single target use of Rio Grande water in both the United States and Mexico, accounting for more than 80% of all the water taken from the river. The main agricultural areas along the river are the San Luis Valley in Colorado, the Rincon and Mesilla Valleys in southern New Mexico, and the El Paso and Juárez Valleys in Texas. While irrigation is the largest use of Rio Grande water, municipal demand for water is steadily increasing. The cities of Albuquerque, El Paso, and Ciudad Juárez have already exhausted much of the area’s readily accessible groundwater. El Paso already is converting some irrigation water to municipal use. About 43% of the city’s annual water supply comes from the Rio Grande River. The city of Las Cruces hopes to start doing the same in the foreseeable future. Rio Grande water generally meets the physiochemical standards of both the U.S. and Mexican governments. Nonpoint sources of pollution, such as runoff from city streets, rangelands, farms, and dairies, appear to be significant sources of microbiological contamination of Rio Grande water. Parasites and viruses are substantially resistant in environments and tend to elude the conventional drinking water treatment processes. Breakdowns or overloading of public water utilities have occasionally resulted in community outbreaks of gastroenteritis. Thus, the microbiological quality of drinking water has been implicated in the spread of viral, bacterial, and parasitic diseases such as diarrhea, dysentery, hepatitis, giardiasis, and cryptosporidiosis. Cattle farming and ranching is the most common activity in the Rio Grande basin and large cattle farms are located in the vicinity of Las Cruces and El Paso. Cattle cryptosporidiosis has worldwide distribution (Fayer, Speer, and Dubey 1997), and Cryptosporidium parvum oocysts are the most important biological