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N C> c:o o l CHAP TER I II STUDY METHODS AND PROCEDURES , , Scope of the Study Previous examinations of salt loadiog processes and of the mechanisms within them have been largely qualitative or based on statistical analysis of empirical data. Theoretical relationships have been proposed, but available data have been limited fot their calibration and integration into models. In searching for sites where data could be collected to support model improve- ment, three situations seemed to merit particular examination: 1. Streams originating iI: upland areas and then flowing onto the lowlands t.o collect salt from di ffuse natural sources in Mancos Shale areas. 2. Natural channels with weathered Mancos Shale material in their beds. 3. Natural channels where seepage enters through their banks or beds, evapo- rates, and leaves salt deposits known as efflorescence. Stream Surveys and Reconnaissance Examination of the Price River Basin was begun during the summer of 1975 with" the objectives of identifying significant diffuse natural salt source areas and of identifying promising study streams. During a second season of field work, emphasis was to be placed on ~on,itoring the water quality on selected streams in an attempt to assess the major salt uptake mechanisms. In addition to looking for the three situations described above, it was also considered desirable 1) that discharge of agricultural drainage into the stream be minimal and 2) that the stream be reasonably accessible from the point of its emergence from the mountains or headwaters to its mouth. Three streams were initially considered for detailed study, namely, Icelander Creek, Brushy Springs Wash, and Cedar Creek (Figure 1.1). Weekly flow and water quality measure- ments were made on each creek from July 16 to August 26, 1975. The streams flow over the Mancos Shales and were expected to exhibit generally high salt loads. Flows were estimated with rectangular cutthroat flumes (Skogethoe et a!. 1967). The following additional equipment was used for field measurements: 1. Yellow Springs S-C-T conductivity meter, model 23 (conductivity) 2. Marsh McBirney water current meter, model 201 (flows) 3. 600 V-notch weirs (low flows) 4. Digi-sense digital pH meter (pH) 5. U. S. Weather Service thermometers (temperature) Most sampleR were analyzed chemically by the '~:ullege of Lii!d.ern Utah chemical laboratory. The remaining chemical analyses were con- ducted by the Utah Water Reseatch Laboratoty, unless otherwise stated. Appendix A de- scribes the <;hemical methods and procedures used. The data obtained from observations on Icelander Creek, Brushy Springs Wash, and Cedar Creek are reported in Appendix B (Tables B.l, B.2, B.3). Cedar Creek exhibited very little flow variation or salt pickup from channel pro- cesses and had an average flow of less than 0.1 cfs and an average TDS of 3,500 mg/l during the sampling period. The stream was easily accessible, but due to extensive channel work for flood control, it could not be regarded as a natural channel. Brushy Springs Wash and Icelander Creek J01n below Highways 6 and 50. Obsetved flows varied from more than 100 cfs to less than I cfs in Icelander and from more than 50 cfs to 0.001 cfs in Brushy Springs Wash. TDS varied from 350 mg/l to 7010 mg/l in lce- landet and from 970 mg/l to 4830 mg/l in Brushy Springs Wash. Intense local thunder- showers occurred over both streams on July 16, 1975, and again on July 29, 1975. Duting each storm event, the flow rose rapidly, TDS dropped, and suspended sediment s increased rapidly. Unfortunately, only one set of samples was taken during each storm event. Like Cedar Creek, during steady flow condi- tions very little salt uptake was noted. Mainly because of poor access, this two- stream system also was rejected for further study. TO facilitate the search for a better study site, a basin-wide water quality survey was conducted on August 26, 1975. The sutvey covered 12 streams with 40 water quality sampling sites. The results are listed in 17