Water Quality Data for the Arkansas River Basin 1990-93

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TYPES OF WATER - QUALITY DATA The types of water - quality data measured and analyzed at each surface -water station are listed in table 1. The surface -water stations are presented in downstream order. Special samples at some stations indicate the irregular collection and analysis of addi- tional water - quality constituents that were appended to routine samples normally collected during station visits. Continuous water - quality and discharge data have been collected at some of the stations, but are not published in this report. However, these data are pub- lished in the annual Colorado Water -Data Report series and are available upon request. The types of water - quality data presented in this report are: 1. Onsite measurements, including instantaneous discharge and field determination of specific conductance, pH, water temperature, and dissolved - oxygen concentration. 2. Bacteriological field analyses, including total coliform, fecal coliform, and fecal strepto- cocci. 3. Dissolved solids, including alkalinity, dissolved calcium, dissolved magnesium, dissolved sodium, dissolved sulfate, dissolved chloride, and dissolved - solids residue at 180 °C. 4. Major nutrients, including total nitrite plus nitrate as nitrogen and total ammonia as nitrogen for 1990 through 1992; dissolved nitrite plus nitrate as nitrogen and dissolved ammonia as nitrogen for 1993; and total phosphorus for 1990 through 1993. 5. Trace elements, including total and dissolved arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, selenium, silver, and zinc. 6. Pesticides, including organochlorine and organo- phosphorus insecticides and the chlorinated phenoxy -acid herbicides. 7. Radiochemical constituents, including total and dissolved gross alpha and gross beta constitu- ents and dissolved natural uranium. 8. Suspended sediment, including suspended - sediment concentration and the percentage of the suspended sediment finer than sand (less than 0.062 mm). Methods of Data Collection and Analysis Before each field trip, a standard cleaning and rinsing procedure was used to prepare the equipment for water - quality sampling. Sampling equipment was completely disassembled and washed thoroughly using a solution of nonphosphate laboratory detergent, fol- lowed by three thorough rinses using public - supplied tap water. Sampling equipment then was rinsed using a 1- percent hydrochloric acid solution and triple- rinsed using deionized water. Upon arriving at each surface -water station, prior to a sample collection, the sampling equipment was rinsed once with deionized water, followed by a rinse with dilute hydrochloric acid, followed by a triple -rinse with deionized water. Finally, the sampling equipment was triple- rinsed thoroughly with native streamwater before the collection of a water - quality sample. At all stations sampled downstream from the Arkansas River near Avondale, station 07109500 (table 1), east of Pueblo to the Colorado -Kansas State line (pl. 1), the dilute hydrochloric acid rinse was omit- ted because trace -level contamination of samples was not a concern in sampling the lower basin. Onsite measurements were made during each site visit at surface -water stations using standardized procedures and techniques (U.S. Geological Survey, 1977). Stream discharge continuously was monitored at some stations or a discharge measurement was made at the time of sampling at other stations. Field water - quality analyses-were made for specific conductance, pH, water temperature, and dissolved oxygen (Fishman and Friedman, 1989). Water samples for bacteriologi- cal analyses were collected onsite at 17 surface - water stations (table 1) with clean sterilized glass bottles using a multivertical sampling procedure (Patrick Edelmann, U.S. Geological Survey, oral commun.,1990). Bacteriological samples were filtered and analyzed in the field using methods described in Britton and Greeson (1987). Water samples for chemical analyses were col- lected using standardized U.S. Geological Survey guidelines (Sylvester and others, 1990). Except for extreme flow situations, surface -water samples from the stream were depth- integrated using the equal - width- increment method (Sylvester and others, 1990) and were transferred into a churn splitter for a compos- ite sample. The churn splitter allowed different sub - sample volumes to be obtained from the sample while still maintaining the basic chemical and physical properties of the original sample. Numerous aliquots were taken from the churn splitter, processed, and preserved onsite using methods described in Ward and Harr (1990). Water - quality samples were shipped on a regular basis to the laboratory for analysis of the chemical constituents. 4 Water - Quality Data for the Arkansas River Basin, Southeastern Colorado, 1990 --93