RIO GRANDE VALLEY, COLORADO, NEW MEXICO, AND TEXAS

摘要: : The Rio Grande Valley National Water-Quality Assessment study unit encompasses about 45,700 square miles in Colorado, New Mexico, and Texas upstream from the gaging station at El Paso, Texas, includes surface-water closed basins east of Continental Divide San Luis Closed Basin Colorado. mean annual precipitation ranges less than 6 to more 50 inches; potential evapo-transpiration 35 80 inches per year. Land use is mainly rangeland, forest land, cropland. Total irrigated acreage 1990 was 914,000 acres water 3,410,000 acre-feet. Two structural settings are found unit: alluvial bedrock basins. can have through-flowing surface or be discussion streamflow quality for system based on four river reaches 750 main stem. ground affected by both natural process human activities nonpoint point sources. Nonpoint sources include agriculture, hydromodification, mining operations; discharge wastewater treatment plants. agriculture septic tanks cesspools; leaking underground storage tanks, unlined manure-lined holding ponds used disposal dairy wastes, landfills, operations.