WSP06816 - Laserfiche WebLink

Home Browse Search

0336 Purpose and Scope This report lists the types of water-quality data collected, describes methods of data-collection, analy- sis, and quality-assurance procedures and presenl~ a compilation ofse!ected water-quality data. Data were collected from April 1990 through March 1993 at 59 surface-water stations in the Arkansas Rivcr Basin of Colorado (pI. I) that included 19 Arkansas River stations, 31 tributary stations, 2 mine-drainage stations, and 7 transmountain diversion stations. Water-quality data presented in this report include onsite mea~ure- ments of instantaneous discharge, specific conduc- tance, pH. water temperature, and dissolved o,:,ygcn; bacteriological analyses; chemical analyses of selected inorganic constituents, pesticides, and radiochcmicals; analyses of suspended-sediment concentration; and analytical quality-assurance data for selected water- quality constituents. Acknowledgments The authors gratefully acknowledge the assis- tance of many government and local agencies that cooperated with the U.S. Geological Survey to develop a ba~inwide water-quality study. Appreciation is cxtended to the many landowners along the Arkansa~ River corridor who permitted access to their property to mea.~ure discharge and to collect water samples. The authors thank State hydrographers Frank Kipple and Tony Gutierrez, Colorado Department of Natural Resources, Division II of Water Resources, Office of the State Engineer, for their timely assistance with streamflow determination. Spccialthanks are cxtended to Jeffrey West, Charles (Chuck) Moore, and Matthew Kurchinski of the U.S. Geological Survey for the collection and compilation of water-quality data. DESCRIPTION OF TME STUDY AREA The study area includes the entire Arkansas River Basin of Colorado and consists of approximately the southeast one-quarter of the State (fig. I). Eleva- tions in the basin range from 3,350 ft above sea level at the Colorado-Kansas State line to 14,433 ft at the high- est mountain peak in Colorado. Mean annual precipi- tation in the basin ranges from more than 40 in. in the mountains to lesS than lOin. in areas of the eastern plains (Colorado Climate Center, 1984). Streamflow in the Arkansas River primarily is from melting of snow that accumulates in the moun- tains from October through May each year. At lower elevations, runoff from summer thunderstorms can contribute substantial quantities of streamflow for short periods of time. Much of the streamflow that occurs east of La Junta (fig. I) can be irrigation-return flow during parts of most years (Cain, 1985). Mean annual runoff decreases from more than 30 in. in the moun- tains to less than 0.1 in. downstream from Pucblo (Abbott, 1985). For the interested reader, a more com- prehensive description of the historical water resources of the Arkansas River Basin of Colorado is reported in Crouch and others (\ 984), Abbott (1985), Bums (1985), Cain (1985). and Kuzmiak and Strickland (1994). Land use in the study area predominantly is agricultural, consisting of rangeland and cropland areas throughout the drainagc basin. National forests are located upstream from Canon City and cover about one-third of the upper Arkansa~ River Basin. The upper basin extends downstream to about Pueblo. Historically, substantial mining of precious metals occurred in the basin upstream from Canon City, but most ofthe mines are abandoned and ranching presently (1994) is a principal land use in the upper ba~in. Irrigation water use constitutes the largest withdrawals of surface water in the Arkansas River Basin. It was estimated that irrigation used about 1,730 Mgalld of water during 1985, with 88 percent of the total irrigation withdrawal from surface- water sources (Litke and Appel, 1989). More than 411,000 acrcs of alluvial lands in the basin are irri- gated, including about 56,000 irrigatcd acres located in the upper basin. Mainly alfalfa, hay, and pa~ture grass are irrigated in the upper basin. although fruits and some grain crops are grown on irrigated land in the foothills located around Canon City. Truck-crops, alfalfa, and grain-crops are grown on irrigated land in the lower basin downstream from Pueblo. Most of the nonirrigated agricultural lands in the ba~in are used for rangeland or dryland wheat production. Population in the study area was determined by the 1990 census (U.S. Burcau of the Census, 1991)lO be 641,700, about 19 percent of the total population of Colorado. Most of the population is located near thc cities of Colorado Springs and Pueblo or concentrated in small towns and ruml areas along the Arkansas River corridor. DESCRIPTION OF TliE STUDY AREA 3