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t <br /> SAN JUAN/DOLORES BASIN April, 1997 <br /> i <br /> Basinwide Conditions Assessment: <br /> The SWSI value of 2.9 indicates that for March the SAN JUAN/DOLORES RIVER BASINS <br /> _iasin water supplies were above normal. The Natural s 9urT"'rwt.. supply Index"'ct9rr <br /> Resources Conservation Service reports April 1 snowpack as ,_ <br /> 111% of normal. Flow at the gaging station Animas River W 3_ �' L d <br /> near Durango averaged 667 cfs as compared to the long term 2 ;: ;.: ` . y <br /> average of 292 cfs. Storage in McPhee,Vallecito, and Lemon ;I <br /> reservoirs totaled 113% of normal as of the end of March. ! - : : '--"' <br /> All of the lower elevation snowpack melted out during i 0 �q' ,.i i f <br /> March and some areas of the basin were actually drying out V ,,...\\/,_--tz. ——\171/11 ,� <br /> due to the windy spring conditions. There was 22 inches of _2- ti i <br /> snow in Durango at the beginning of March which declined to a : <br /> a trace by the 21st. An early April snow storm brought some -3- - 1 <br /> welcome precipitation. Durango's year to date precipitation - 1 <br /> JAN88 JAN89 JAN90 JAN91 JAN92 JAN93 JAN91 JAN9S JAN96 JAN97 <br /> total is 1.69 inches, which is still an excellent 177% of NONTW YEAR <br /> average. <br /> River flows significantly exceeded historic averages. <br /> Stream gages on the Dolores, Animas, and others recorded <br /> well over 200%of normal flow as the lower snowpack melted <br /> out. The La Plata River ran at 351% of average. ANIMAS RIVER NR. DURANGO <br /> FLOW BY WATER YEAR <br /> 240 <br /> 230 <br /> Outlook 220 <br /> 210 <br /> March 1997 shows how quickly conditions can change 9a <br /> and illustrates the uncertainty of predicting runoff based on .. leo <br /> January or February snowpack. The percent of average nn ;so ��7,.... z_ <br /> snowpack fell drastically during March, from 146%to 111%, 140 <br /> 1 130 <br /> due to no precipitation during the month. The high elevation LL s 120 <br /> WP 110 <br /> snow fields in the San Juan and San Miguel Mountains 3" 10 <br /> remain above average. Therefore,basin administrators believe 70 �— <br /> 5. <br /> that most reservoirs will fill and a longer period of runoff will 5.3 �� <br /> occur. If enough precipitation comes to keep soil moisture �— <br /> z0 <br /> replenished the water year will be an excellent one for io <br /> Oct NDv .. Jon Fob March Apr II <br /> southwest Colorado. kONTH <br /> 0 WET C 1973) 0 DRY(1977) C AVG X 1997 <br /> Administrative/Management Concerns <br /> Reservoirs were regulated differently across the basin. <br /> Vallecito Reservoir made significant early releases in <br /> anticipation of fill during runoff. Lemon Reservoir and REPRESENTATIVE RESERVOIRS <br /> Jackson Reservoir continued water storage efforts. Release 3•10 °°`° S AN1MM5 RIVER BASINS <br /> from McPhee Reservoir was about 60 cfs for fish flows. 30o= <br /> no- <br /> 2s /z,o <br /> ; 220 7\ <br /> y 2 200 <br /> • 180...../.7\ <br /> •• <br /> , 180 <br /> • 120 <br /> • 100 <br /> n <br /> /\ <br /> 80— <br /> SO 40 <br /> ,,ram <br /> 20 //�/J/////�� , <br /> mcphw V•11.1%. 1-8111oR <br /> ® ASV. 3/91 C0nt•nt• ® 3/31/97 cont.,. <br /> A . 9 <br />