Laserfiche WebLink
<br /> <br />1,000 <br /> <br />W <br />()a: CfJ <br />ZW ::J <br /><(O-f-- <br />I-(I)<~ <br />()z' W <br />::Jwffi() <br />O:;;f-CfJ <br />zwww <br />O(ij:;;w <br />()o-a: <br />()a:~(!) <br />u:gww <br />-~()o <br />()~ '" <br />Wz C\J <br />0-_ <br />CfJ <br /> <br />500 <br /> <br />1 <br />." 3 6 <br />"'~IJ" 5 ____~--- <br />2- '..----- <br /> <br />d <br /> <br />o <br />230 220 <br /> <br />200 <br /> <br />180 <br /> <br />160 <br /> <br />. ! ,~> <br /> <br />10 <br />o <br /> <br />07 <br /> <br />11 12 <br /> <br />_-------.t---------9I1J1C------------ <br /> <br />--- <br /> <br />140 <br /> <br />100 <br /> <br />20 <br /> <br />o <br /> <br />80 <br /> <br />60 <br /> <br />40 <br /> <br />120 <br /> <br />DISTANCE FROM MOUTH OF YAMPA RIVER, IN RIVER MILES <br />EXPLANATION <br /> <br />-.- Specific conductance at Yampa River site <br />D Specific conductance at tributary site <br />Note: number by symbol is site number in tables 1 and 3 <br /> <br />Figure 3, Specific conductance at Yampa River and tributary sites, August 16-19,1999, <br /> <br />Williams Fork at mouth (site 7), with a specific <br />conductance of 527 ~S!cm, and Little Snake River <br />above Yampa River (site 10), with a specific conduc- <br />tance of 809 ~S!cm, Evaporation from the river <br />channel, irrigation return flows, sewage effluent, and <br />inflow of saltier ground water are other potential <br />contributors (0 the downstream increase in salinity, <br /> <br />Downstream trends in concentrations of calcium <br />and alkalinity (fig, 4), important controls on pH and on <br />the capacity of the waters to dissolve or precipitate <br />calcite (CaC03), were similar to trends for specific <br />conductance (fig, 3), Concentrations between Yampa <br />River below Stagecoach Reservoir (site I) and Yampa <br />River at Steamboat Springs (site 2) were diluted by <br />fresher water in tributary creeks, Downstream frolll <br />Yampa River above Elk River (site 3), concentrations <br />of calcium and alkalinity were substantially diluted by <br />freshwater from the Elk River (site 4), From Yampa <br />River below diversion near Hayden (site 5) to Yampa <br />River at mouth (site 12), concentrations of calcium <br />increased to 40 mg/L and alkalinity increased to <br />140 mg/L of'alkalinity as CaC03, primarily because of <br />inflow of more alkaline water from the Williams Fork <br />(site 7) and the Little Snake River (site 10), <br /> <br />At Yainpa River sites, pH (fig, 5) ranged from <br />8,46 to 9,20; pH ranged from 8,08 to 8,70 at the three <br />tributary sites, which were sampled during early after- <br />noon before pH would be expected to peak because of <br />photosynthesis, The smallest measured pH value in the <br /> <br />Yampa River (8,46) was at site I, below Stagecoach <br />Reservoir, only about 0,25 mile downstream from the <br />darn spillway, Because this water was released from <br />substantial depth in the reservoir, pH had little poten- <br />tial to be affected by the cumulative effects of photo- <br />synthesis, However, water from this site had theJargest <br />measured concentrations of dissolved ammonia <br />(0,02 mg/L as N), dissolved nitrite plus nitrate <br />(0,10 mg/L as N), dissolved ammonia plus organic <br />nitrogen (0.36 mg/L as N), dissolved organic carbon <br />(5,4 mg/L as C), and the second largest measured <br />concentration of dissolved phosphorus (0,05 mg/L as <br />Plat Yampa River and tributary-river sites, In addition, <br />the rocky streambed was covered with aquatic vegeta- <br />tion, <br /> <br />The largest pH value (9.20), measured at Yampa <br />River above Elk River (site 3), exceeded the Colorado <br />water-quality standard of 9,0 for the upper Colorado <br />River Basin, Site 3 is about 1.8 miles downstream <br />from the sewage outfall from the SSRWWTP, This <br />facility discharges about 3,9 ft3/s of treated sewage <br />effluent during summer daylight hours (David Jarvis, <br />Steamboat Springs Regional Waste Water Treatment <br />Plant, oral commun" 2000), indicating a fortyfold <br />dilution of sewage effluent at site 3 during sampling, <br />The river channel exhibited abundant attached algae <br />and occasional clumps of entrained algae, indicating <br />photosynthesis induced by nutrient enrichment from <br />sewage effluent. The large pH was accompanied by a <br /> <br />8 Evaluation of Trends in pH in the Vampa River, NorthWestern Colorado, 1950-2000 <br />