United States Natural Resources Water and Climate Center Department of Conservation Portland, Oregon Agriculture Service S N O W - P R E C I P I T A T I O N U P D A T E Based on Mountain Data from NRCS SNOTEL Sites As of SUNDAY: APRIL 28 , 2024 ------------------------------------------------------------------------------ BASIN ELEV. SNOW WATER EQUIVALENT TOTAL PRECIPITATION Data Site Name (Ft) % % Current Median Median Current Median Med ------------------------------------------------------------------------------ UPPER COLORADO RIVER BASIN UPPER GREEN RIVER BASIN Big Sandy Opening 9080 11.0 12.6 87 15.6 14.8 105 Blacks Fork Jct 8869 4.0 5.0 80 14.8 14.1 105 Blind Bull Sum 8650 24.4 24.8 98 18.0 19.2 94 Buck Pasture 9632 10.5 -M * 17.8 -M * East Rim Divide 7930 -M 7.8 * 12.0 12.2 98 EF Blacks Fork GS 9360 4.9 8.2 60 10.8 13.2 82 Elkhart Park G.S. 9400 8.0 11.8 68 12.9 13.8 93 Gros Ventre Summit 8750 9.7 12.8 76 -M 14.2 * Gunsight Pass 9820 11.3 13.2 86 15.8 16.0 99 Hams Fork 7840 -M 4.8 * 12.8 11.8 108 Hewinta 9500 4.6 6.6 70 15.7 15.6 101 Hickerson Park 9122 2.8 4.4 64 14.5 12.0 121 Hole-in-Rock 9168 2.0 4.0 50 11.7 11.6 101 Indian Creek 9425 22.0 23.0 96 22.2 21.0 106 Kelley R.S. 8180 12.2 12.4 98 19.6 17.8 110 Kendall R.S. 7740 2.3 5.6 41 13.8 14.2 97 Kings Cabin 8728 .4 5.0 8 13.8 14.4 96 Loomis Park 8240 6.6 11.8 56 16.1 17.7 91 New Fork Lake 8340 1.5 6.8 22 -M 11.8 * Pocket Creek 9360 -M -M * -M -M * Snider Basin 8060 4.9 8.2 60 14.5 14.9 97 Spirit Lk 10235 10.6 12.6 84 19.8 19.4 102 Spring Creek Divide 9000 23.6 25.3 93 23.8 25.2 94 Steel Creek Park 10158 14.5 16.9 86 19.0 18.3 104 Triple Peak 8500 17.1 19.6 87 26.5 27.6 96 Trout Creek 9518 2.7 7.7 35 13.1 15.0 87 ----- ----- Basin Index (%) 78 99 DUCHESNE RIVER BASIN Brown Duck 10574 16.8 17.6 95 21.4 19.8 108 Chepeta 10499 8.0 13.0 62 16.2 16.2 100 Currant Creek 7915 .4 .0 * 16.6 13.6 122 Daniels-Strawberry 8008 3.5 2.7 130 20.3 18.4 110 Five Points Lake 10943 17.1 17.0 101 19.8 20.1 99 Wilbur Bench 9171 2.5 4.7 53 15.0 14.5 103 Kings Cabin 8728 .4 5.0 8 13.8 14.4 96 Lakefork #1 10128 8.1 10.6 76 16.1 15.2 106 Lakefork #3 8464 .4 .0 * 11.2 10.8 104 Lakefork Basin 10885 20.7 21.7 95 23.1 24.2 95 Mosby Mtn. 9553 7.4 8.7 85 14.2 15.6 91 Rock Creek 7886 .4 .0 * 13.2 11.6 114 Strawberry Divide 8123 10.0 7.0 143 26.4 18.2 145 Trial Lake 9992 26.5 23.0 115 28.7 24.4 118 White River #1 8641 5.6 4.4 127 18.1 14.2 127 ----- ----- Basin Index (%) 94 109 YAMPA/WHITE RIVER BASINS Battle Mountain 7498 -M .8 * 19.9 17.3 115 Bear River 9112 10.2 11.5 89 16.2 15.4 105 Bison Lake 10964 24.3 25.4 96 27.3 28.6 95 Buffalo Park 9249 13.0 12.7 102 18.8 18.1 104 Burro Mountain 9317 6.6 11.6 57 24.4 22.4 109 Columbine 9167 16.2 19.5 83 28.3 28.6 99 Crosho 8973 6.9 5.4 128 21.4 17.8 120 Divide Peak 8730 14.4 17.1 84 25.7 24.6 104 Dry Lake 8271 18.0 14.4 125 31.8 27.5 116 Elk River 8739 8.6 13.0 66 21.6 22.0 98 Little Snake River 8928 23.2 23.9 97 35.9 36.4 99 Lost Dog 9327 21.0 21.8 96 26.2 26.2 100 Lynx Pass 8919 2.6 5.4 48 18.2 14.5 126 Old Battle 9860 33.3 35.8 93 36.0 37.5 96 Rabbit Ears 9411 25.9 27.4 95 37.9 33.6 113 Ripple Creek 10350 27.3 27.6 99 30.9 29.2 106 Sage Creek Basin 7850 2.8 1.5 187 16.1 14.4 112 Sandstone RS 8152 7.0 6.8 103 19.7 19.2 103 Tower 10620 43.0 46.2 93 43.4 45.0 96 Trapper Lake 9759 6.3 -M * 22.4 21.4 105 Whiskey Park 9020 26.9 26.6 101 32.0 31.6 101 ----- ----- Basin Index (%) 94 104 PRICE-SAN RAFAEL Buck Flat 9409 10.1 12.7 80 19.9 19.4 103 Clear Creek #1 8975 15.8 12.0 132 23.3 20.3 115 Corral 8207 .4 -M * 14.8 -M * Huntington Horse 9652 20.1 -M * 26.3 -M * Mammoth-Cottonwood 8709 15.4 12.4 124 21.8 15.8 138 Red Pine Ridge 8988 8.6 8.6 100 21.1 19.3 109 Seeley Creek 9904 12.9 12.4 104 15.8 14.7 107 Timberline 8736 1.5 .7 214* 16.9 15.6 108 Upper Joes Valley 8596 .0 -M * 15.0 -M * White River #1 8641 5.6 4.4 127 18.1 14.2 127 Wrigley Creek 9327 2.7 -M * 15.9 -M * ----- ----- Basin Index (%) 111 115 ESCALANTE RIVER BASINS Clayton Springs 10049 8.5 4.4 193 16.7 16.0 104 Donkey Reservoir 9799 4.6 2.8 164 13.4 11.0 122 Sunflower Flat 10018 11.0 -M * 14.9 -M * Widtsoe #3 9640 9.2 6.7 137 17.9 15.2 118 ----- ----- Basin Index (%) 160 114 DIRTY DEVIL RIVER BASIN Black Flat-U.M. Ck 9414 3.1 2.9 107 12.6 12.5 101 Dills Camp 9228 2.4 5.7 42 18.2 18.2 100 Donkey Reservoir 9799 4.6 2.8 164 13.4 11.0 122 Fish Lake Utah 8798 2.0 .0 * -M 9.0 * Lonesome Beaver 9410 .8 -M * 13.5 -M * Sunflower Flat 10018 11.0 -M * 14.9 -M * ----- ----- Basin Index (%) 106 106 UPPER COLORADO RIVER HEADWATERS Arapaho Ridge 10976 21.6 23.6 92 24.3 25.0 97 Beaver Ck Village 8565 6.1 5.8 105 16.7 16.7 100 Berthoud Summit 11314 23.8 21.8 109 31.4 27.0 116 Bison Lake 10964 24.3 25.4 96 27.3 28.6 95 Buffalo Park 9249 13.0 12.7 102 18.8 18.1 104 Columbine 9167 16.2 19.5 83 28.3 28.6 99 Copper Mountain 10523 15.5 16.4 95 18.0 19.4 93 Elliot Ridge 10549 23.4 21.0 111 22.4 -M * Fool Creek 11156 23.5 -M * 23.9 -M * Fremont Pass 11326 19.1 19.5 98 20.6 19.4 106 Grizzly Peak 11139 18.4 17.8 103 20.0 20.4 98 High Lonesome 10638 23.8 -M * 26.0 -M * Hoosier Pass 11611 18.3 16.6 110 20.0 18.7 107 Lake Irene 10682 22.6 23.6 96 25.2 23.4 108 Lynx Pass 8919 2.6 5.4 48 18.2 14.5 126 Phantom Valley 9045 7.8 5.4 144 16.0 15.4 104 Stillwater Creek 8880 .2 -M * 14.3 11.6 123 Summit Ranch 9371 5.1 8.3 61 16.8 15.6 108 Vail Mountain 10310 17.7 18.9 94 21.7 23.1 94 Willow Creek Pass 9523 15.4 15.3 101 17.3 15.7 110 ----- ----- Basin Index (%) 98 104 ROARING FORK RIVER BASIN Chapman Tunnel 10100 13.7 13.3 103 21.9 19.7 111 Independence Pass 10598 14.3 16.4 87 20.5 20.0 102 Ivanhoe 10541 20.9 16.2 129 26.0 23.8 109 Kiln 9624 8.2 8.7 94 17.7 16.3 109 Mc Clure Pass 8774 4.0 9.8 41 20.9 22.0 95 Nast Lake 8731 .8 .0 * 16.6 13.5 123 North Lost Trail 9219 7.9 9.5 83 21.6 24.2 89 Schofield Pass 10653 25.6 31.0 83 33.1 33.4 99 ----- ----- Basin Index (%) 91 103 SOUTH EASTERN UTAH Buckboard Flat 8924 4.1 -M * 17.8 -M * Camp Jackson 8858 .6 .3 200* 16.8 18.6 90 East Willow Creek 8302 .2 .0 * 11.7 12.6 93 Lasal Mountain 9578 1.6 3.5 46 18.5 20.6 90 Lasal Mountain-Lower 8783 .4 -M * 13.3 -M * Lonesome Beaver 9410 .8 -M * 13.5 -M * ----- ----- Basin Index (%) 63* 91 GUNNISON RIVER BASIN Butte 10200 9.5 10.6 90 19.0 16.6 114 Cochetopa Pass 10061 .5 .0 * 8.3 8.7 95 Columbine Pass 9171 2.4 4.2 57 21.4 24.8 86 Idarado 9812 3.7 9.2 40 17.6 22.0 80 Mc Clure Pass 8774 4.0 9.8 41 20.9 22.0 95 Mesa Lakes 10168 9.9 16.2 61 21.7 23.4 93 Overland Res. 9893 2.3 7.1 32 15.7 17.7 89 Park Cone 9621 9.1 7.7 118 15.2 12.2 125 Park Reservoir 9987 17.0 26.0 65 24.4 28.6 85 Porphyry Creek 10788 16.1 14.4 112 24.3 17.8 137 Red Mountain Pass 11080 19.5 23.8 82 25.5 29.0 88 Sargents Mesa 11499 8.2 10.1 81 13.5 14.2 95 Schofield Pass 10653 25.6 31.0 83 33.1 33.4 99 Slumgullion 11560 6.7 13.4 50 14.3 15.6 92 Upper Taylor 10717 8.3 10.3 81 22.9 17.8 129 Wager Gulch 11132 5.0 -M * 14.0 -M * ----- ----- Basin Index (%) 74 98 DOLORES/SAN MIGUEL RIVER BASINS Black Mesa 11564 19.8 -M * 23.9 -M * El Diente Peak 10217 7.4 8.3 89 20.3 21.5 94 Lizard Head Pass 10193 9.5 11.7 81 15.2 17.3 88 Lone Cone 9755 .8 5.2 15 18.7 21.7 86 Mancos 10044 3.9 3.8 103 15.2 19.2 79 Mineral Creek 10046 6.9 11.4 61 17.2 19.4 89 Red Mountain Pass 11080 19.5 23.8 82 25.5 29.0 88 Scotch Creek 9195 .2 .0 * 16.7 18.4 91 Sharkstooth 10747 10.7 15.6 69 21.0 22.6 93 ----- ----- Basin Index (%) 74 89 SAN JUAN RIVER HEADWATERS Beartown 11600 16.8 19.8 85 23.1 25.6 90 Chamita 8383 .3 .0 * 12.0 13.8 87 Lily Pond 11069 4.3 9.1 47 17.6 21.2 83 Middle Creek 11269 12.6 17.8 71 20.3 24.8 82 Stump Lakes 11248 15.2 17.4 87 21.9 21.1 104 Upper San Juan 10140 16.8 25.4 66 30.0 36.8 82 Vallecito 10782 8.4 9.7 87 16.7 19.3 87 Weminuche Creek 10749 6.6 8.2 80 22.4 22.7 99 Wolf Creek Summit 10957 21.6 34.1 63 26.8 35.7 75 ----- ----- Basin Index (%) 73 86 ANIMAS RIVER BASIN Beartown 11600 16.8 19.8 85 23.1 25.6 90 Cascade 8880 -M .0 * -M 21.2 * Cascade #2 9012 .2 .0 * 15.4 20.3 76 Columbus Basin 10781 20.8 22.6 92 26.3 28.8 91 Mineral Creek 10046 6.9 11.4 61 17.2 19.4 89 Molas Lake 10631 8.0 18.9 42 18.3 22.3 82 Red Mountain Pass 11080 19.5 23.8 82 25.5 29.0 88 Spud Mountain 10674 11.4 19.0 60 26.1 32.4 81 Stump Lakes 11248 15.2 17.4 87 21.9 21.1 104 ----- ----- Basin Index (%) 74 87 COLORADO RIVER BASIN ABOVE LAKE POWELL (TOTAL OF ALL SNOTEL SITES) Beartown 11600 16.8 19.8 85 23.1 25.6 90 Black Mesa 11564 19.8 -M * 23.9 -M * Slumgullion 11560 6.7 13.4 50 14.3 15.6 92 Sargents Mesa 11499 8.2 10.1 81 13.5 14.2 95 Hoosier Pass 11611 18.3 16.6 110 20.0 18.7 107 Fremont Pass 11326 19.1 19.5 98 20.6 19.4 106 Berthoud Summit 11314 23.8 21.8 109 31.4 27.0 116 Middle Creek 11269 12.6 17.8 71 20.3 24.8 82 Stump Lakes 11248 15.2 17.4 87 21.9 21.1 104 Red Mountain Pass 11080 19.5 23.8 82 25.5 29.0 88 Fool Creek 11156 23.5 -M * 23.9 -M * Wager Gulch 11132 5.0 -M * 14.0 -M * Grizzly Peak 11139 18.4 17.8 103 20.0 20.4 98 Wolf Creek Summit 10957 21.6 34.1 63 26.8 35.7 75 Lily Pond 11069 4.3 9.1 47 17.6 21.2 83 Arapaho Ridge 10976 21.6 23.6 92 24.3 25.0 97 Five Points Lake 10943 17.1 17.0 101 19.8 20.1 99 Lakefork Basin 10885 20.7 21.7 95 23.1 24.2 95 Vallecito 10782 8.4 9.7 87 16.7 19.3 87 Bison Lake 10964 24.3 25.4 96 27.3 28.6 95 Columbus Basin 10781 20.8 22.6 92 26.3 28.8 91 Porphyry Creek 10788 16.1 14.4 112 24.3 17.8 137 Weminuche Creek 10749 6.6 8.2 80 22.4 22.7 99 Schofield Pass 10653 25.6 31.0 83 33.1 33.4 99 Lake Irene 10682 22.6 23.6 96 25.2 23.4 108 Spud Mountain 10674 11.4 19.0 60 26.1 32.4 81 Upper Taylor 10717 8.3 10.3 81 22.9 17.8 129 High Lonesome 10638 23.8 -M * 26.0 -M * Independence Pass 10598 14.3 16.4 87 20.5 20.0 102 Brown Duck 10574 16.8 17.6 95 21.4 19.8 108 Copper Mountain 10523 15.5 16.4 95 18.0 19.4 93 Elliot Ridge 10549 23.4 21.0 111 22.4 -M * Tower 10620 43.0 46.2 93 43.4 45.0 96 Molas Lake 10631 8.0 18.9 42 18.3 22.3 82 Chepeta 10499 8.0 13.0 62 16.2 16.2 100 Ivanhoe 10541 20.9 16.2 129 26.0 23.8 109 Ripple Creek 10350 27.3 27.6 99 30.9 29.2 106 Vail Mountain 10310 17.7 18.9 94 21.7 23.1 94 Spirit Lk 10235 10.6 12.6 84 19.8 19.4 102 Upper San Juan 10140 16.8 25.4 66 30.0 36.8 82 Lizard Head Pass 10193 9.5 11.7 81 15.2 17.3 88 Butte 10200 9.5 10.6 90 19.0 16.6 114 Steel Creek Park 10158 14.5 16.9 86 19.0 18.3 104 Lakefork #1 10128 8.1 10.6 76 16.1 15.2 106 Chapman Tunnel 10100 13.7 13.3 103 21.9 19.7 111 Clayton Springs 10049 8.5 4.4 193 16.7 16.0 104 Mineral Creek 10046 6.9 11.4 61 17.2 19.4 89 Cumbres Trestle 10035 18.0 20.5 88 22.5 26.4 85 Cochetopa Pass 10061 .5 .0 * 8.3 8.7 95 Sunflower Flat 10018 11.0 -M * 14.9 -M * Old Battle 9860 33.3 35.8 93 36.0 37.5 96 Mesa Lakes 10168 9.9 16.2 61 21.7 23.4 93 Mancos 10044 3.9 3.8 103 15.2 19.2 79 El Diente Peak 10217 7.4 8.3 89 20.3 21.5 94 Trial Lake 9992 26.5 23.0 115 28.7 24.4 118 Park Reservoir 9987 17.0 26.0 65 24.4 28.6 85 Seeley Creek 9904 12.9 12.4 104 15.8 14.7 107 Overland Res. 9893 2.3 7.1 32 15.7 17.7 89 Gunsight Pass 9820 11.3 13.2 86 15.8 16.0 99 Idarado 9812 3.7 9.2 40 17.6 22.0 80 Donkey Reservoir 9799 4.6 2.8 164 13.4 11.0 122 Trapper Lake 9759 6.3 -M * 22.4 21.4 105 Huntington Horse 9652 20.1 -M * 26.3 -M * Widtsoe #3 9640 9.2 6.7 137 17.9 15.2 118 Buck Pasture 9632 10.5 -M * 17.8 -M * Park Cone 9621 9.1 7.7 118 15.2 12.2 125 Lone Cone 9755 .8 5.2 15 18.7 21.7 86 Kiln 9624 8.2 8.7 94 17.7 16.3 109 Lasal Mountain 9578 1.6 3.5 46 18.5 20.6 90 Mosby Mtn. 9553 7.4 8.7 85 14.2 15.6 91 Willow Creek Pass 9523 15.4 15.3 101 17.3 15.7 110 Trout Creek 9518 2.7 7.7 35 13.1 15.0 87 Mc Clure Pass 8774 4.0 9.8 41 20.9 22.0 95 Hewinta 9500 4.6 6.6 70 15.7 15.6 101 Mccoy Park 9516 9.7 9.6 101 21.4 19.6 109 Indian Creek 9425 22.0 23.0 96 22.2 21.0 106 Black Flat-U.M. Ck 9414 3.1 2.9 107 12.6 12.5 101 Buck Flat 9409 10.1 12.7 80 19.9 19.4 103 Summit Ranch 9371 5.1 8.3 61 16.8 15.6 108 Rabbit Ears 9411 25.9 27.4 95 37.9 33.6 113 Elkhart Park G.S. 9400 8.0 11.8 68 12.9 13.8 93 Columbine Pass 9171 2.4 4.2 57 21.4 24.8 86 Burro Mountain 9317 6.6 11.6 57 24.4 22.4 109 Pocket Creek 9360 -M -M * -M -M * EF Blacks Fork GS 9360 4.9 8.2 60 10.8 13.2 82 Wrigley Creek 9327 2.7 -M * 15.9 -M * Lost Dog 9327 21.0 21.8 96 26.2 26.2 100 Buffalo Park 9249 13.0 12.7 102 18.8 18.1 104 Dills Camp 9228 2.4 5.7 42 18.2 18.2 100 North Lost Trail 9219 7.9 9.5 83 21.6 24.2 89 Hole-in-Rock 9168 2.0 4.0 50 11.7 11.6 101 Columbine 9167 16.2 19.5 83 28.3 28.6 99 Hickerson Park 9122 2.8 4.4 64 14.5 12.0 121 Scotch Creek 9195 .2 .0 * 16.7 18.4 91 Crosho 8973 6.9 5.4 128 21.4 17.8 120 Big Sandy Opening 9080 11.0 12.6 87 15.6 14.8 105 Bear River 9112 10.2 11.5 89 16.2 15.4 105 Phantom Valley 9045 7.8 5.4 144 16.0 15.4 104 Spring Creek Divide 9000 23.6 25.3 93 23.8 25.2 94 Red Pine Ridge 8988 8.6 8.6 100 21.1 19.3 109 Whiskey Park 9020 26.9 26.6 101 32.0 31.6 101 Middle Fork Camp 8969 6.9 6.6 105 18.6 17.2 108 Buckboard Flat 8924 4.1 -M * 17.8 -M * Cascade #2 9012 .2 .0 * 15.4 20.3 76 Lynx Pass 8919 2.6 5.4 48 18.2 14.5 126 Divide Peak 8730 14.4 17.1 84 25.7 24.6 104 Cascade 8880 -M .0 * -M 21.2 * Blacks Fork Jct 8869 4.0 5.0 80 14.8 14.1 105 Camp Jackson 8858 .6 .3 200* 16.8 18.6 90 Fish Lake Utah 8798 2.0 .0 * -M 9.0 * Lasal Mountain-Lower 8783 .4 -M * 13.3 -M * Gros Ventre Summit 8750 9.7 12.8 76 -M 14.2 * Timberline 8736 1.5 .7 214* 16.9 15.6 108 Kings Cabin 8728 .4 5.0 8 13.8 14.4 96 Stillwater Creek 8880 .2 -M * 14.3 11.6 123 Mammoth-Cottonwood 8709 15.4 12.4 124 21.8 15.8 138 Nast Lake 8731 .8 .0 * 16.6 13.5 123 Elk River 8739 8.6 13.0 66 21.6 22.0 98 Blind Bull Sum 8650 24.4 24.8 98 18.0 19.2 94 White River #1 8641 5.6 4.4 127 18.1 14.2 127 Upper Joes Valley 8596 .0 -M * 15.0 -M * Triple Peak 8500 17.1 19.6 87 26.5 27.6 96 Beaver Ck Village 8565 6.1 5.8 105 16.7 16.7 100 Lakefork #3 8464 .4 .0 * 11.2 10.8 104 Dry Lake 8271 18.0 14.4 125 31.8 27.5 116 Chamita 8383 .3 .0 * 12.0 13.8 87 New Fork Lake 8340 1.5 6.8 22 -M 11.8 * East Willow Creek 8302 .2 .0 * 11.7 12.6 93 Loomis Park 8240 6.6 11.8 56 16.1 17.7 91 Corral 8207 .4 -M * 14.8 -M * Kelley R.S. 8180 12.2 12.4 98 19.6 17.8 110 Sandstone RS 8152 7.0 6.8 103 19.7 19.2 103 Strawberry Divide 8123 10.0 7.0 143 26.4 18.2 145 Snider Basin 8060 4.9 8.2 60 14.5 14.9 97 Daniels-Strawberry 8008 3.5 2.7 130 20.3 18.4 110 East Rim Divide 7930 -M 7.8 * 12.0 12.2 98 Currant Creek 7915 .4 .0 * 16.6 13.6 122 Rock Creek 7886 .4 .0 * 13.2 11.6 114 Hams Fork 7840 -M 4.8 * 12.8 11.8 108 Kendall R.S. 7740 2.3 5.6 41 13.8 14.2 97 Battle Mountain 7498 -M .8 * 19.9 17.3 115 ----- ----- Basin Index (%) 87 100 ----------------------------------------------------------------------------- -M = Missing data * = Data may not provide a valid measure of conditions. Units = inches for the Current and Median (or Average) Snow Water Equivalent and Total Precipitation values If the Basin Index (%) value is flagged as potentially invalid, care should be taken to evaluate if the value is representative of conditions in the basin. The SNOW WATER EQUIVALENT Percent of Median (or Average) represents the snow water equivalent found at selected SNOTEL sites in or near the basin compared to the Median (or Average) value for those sites on this day. The TOTAL PRECIPITATION Percent of Median (or Average) represents the total precipitation (beginning October 1st) found at selected SNOTEL sites in or near the basin compared to the Median (or Average) value for those sites on this day. Contact your state water supply staff for assistance. Medians and averages are calculated for the period 1991-2020. Provisional data, subject to revision. * Site -- Either: (a) the current value is missing; (b) the median or average for the day is not available or is zero; or (c) for snow water equivalent, the median or average for the day is less than 10% of the maximum median or average value for the year. * Basin - More than half of the stations for a basin with medians (or averages) report missing or invalid data The basin index is calculated as the sum of the valid current values divided by the sum of the corresponding medians or averages and the resulting fraction multiplied by 100.