Utah Water Supply Outlook Report Natural Resources Conservation Service Salt Lake City, UT

Utah Water Supply

Outlook Report March 1, 2021

Cascade Mountain SNOTEL site Photo by Dave Eiriksson

Water Supply Outlook Reports and Federal - State - Private Cooperative Snow Surveys

For more water supply and resource management information, contact: your local Natural Resources Conservation Service Office or: Snow Surveys 245 N Jimmy Doolittle Rd, SLC Utah, 84116. Phone (385)285-3118 Email Address: [email protected]

How forecasts are made

Most of the annual streamflow in the western United States originates as snowfall that has accumulated in the mountains during the winter and early spring. As the snowpack accumulates, hydrologists estimate the runoff that will occur when it melts. Measurements of snow water equivalent at selected manual snowcourses and automated SNOTEL sites, along with precipitation, antecedent streamflow, and indices of the El Niño / Southern Oscillation are used in statistical and simulation models to prepare runoff forecasts. Unless otherwise specified, all forecasts are for flows that would occur naturally without any upstream influences.

Forecasts of any kind, of course, are not perfect. Streamflow forecast uncertainty arises from three primary sources: (1) uncertain knowledge of future weather conditions, (2) uncertainty in the forecasting procedure, and (3) errors in the data. The forecast, therefore, must be interpreted not as a single value but rather as a range of values with specific probabilities of occurrence. The middle of the range is expressed by the 50% exceedance probability forecast, for which there is a 50% chance that the actual flow will be above, and a 50% chance that the actual flow will be below, this value. To describe the expected range around this 50% value, four other forecasts are provided, two smaller values (90% and 70% exceedance probability) and two larger values (30%, and 10% exceedance probability). For example, there is a 90% chance that the actual flow will be more than the 90% exceedance probability forecast. The others can be interpreted similarly.

The wider the spread among these values, the more uncertain the forecast. As the season progresses, forecasts become more accurate, primarily because a greater portion of the future weather conditions become known; this is reflected by a narrowing of the range around the 50% exceedance probability forecast. Users should take this uncertainty into consideration when making operational decisions by selecting forecasts corresponding to the level of risk they are willing to assume about the amount of water to be expected. If users anticipate receiving a lesser supply of water, or if they wish to increase their chances of having an adequate supply of water for their operations, they may want to base their decisions on the 90% or 70% exceedance probability forecasts, or something in between. On the other hand, if users are concerned about receiving too much water (for example, threat of flooding), they may want to base their decisions on the 30% or 10% exceedance probability forecasts, or something in between. Regardless of the forecast value users choose for operations, they should be prepared to deal with either more or less water. (Users should remember that even if the 90% exceedance probability forecast is used, there is still a 10% chance of receiving less than this amount.) By using the exceedance probability information, users can easily determine the chances of receiving more or less water.

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SUMMARY

The storms we received in February gave Utah’s snowpack a nice boost: from 6.2” statewide snow water equivalent (SWE) at the beginning of the month to 10.2” by March 1st. While it's statistically very unlikely that Utah will reach 'normal' peak snowpack conditions by early April, this extra SWE has improved our outlook for runoff when it all melts. Unfortunately, the outlook is still pretty dire…

As of March 1st, the snow water equivalent (SWE) measured at our SNOTEL sites is 77% of normal statewide, compared with 65% last month. The Southwestern Utah, Southeastern Utah, and Price-San Rafael basin are faring the worst at 55%, 62%, and 63% of normal SWE, respectively. With only one month remaining until our typical snowpack peak, our statewide SWE needs to improve by 5.3” to achieve ‘normal’ conditions, which now only has a <10% likelihood of occurring. February precipitation was above average at 111%, but the water-year-to-date precipitation for the state remains well below average at only 70%. Soil moisture levels in the state remain exceptionally dry—currently at only 29% of saturation (or roughly 57% of normal). As noted in last month’s report, Utah’s poor snowpack conditions, extremely dry soils, and low antecedent streamflow are impacting runoff conditions; streamflow forecasts for April to July snowmelt runoff volume are generally between 25% and 75% of average. The largest improvements are in areas hit hardest by February’s storms, such as the forecast for Big Cottonwood Creek which increased by nearly 20%. On the other hand, several forecast points remain extremely low, such as South Creek near Monticello (22% of normal) and others.

Utah’s reservoir storage is currently at 67% of capacity, down 14% from last year. When combined with the low forecasts, the resulting Surface Water Supply Indices for Utah basins are alarmingly low. It is now very likely that Utah will experience below to well-below average water supply conditions for the 2021 water year. Water managers should plan accordingly.

SNOWPACK

Statewide snowpack is below normal at 77% compared to 104% last year. The basins with the highest percent normal SWE are the Raft (108%), Tooele Valley-Vernon Creek (82%), and the Bear (80%).

PRECIPITATION

February precipitation across the state was above average at 111%, which brings the seasonal accumulation (Oct- Feb) to 70% of average. All Utah watersheds are between 55% and 92% of average, with the lowest values for the Southwestern Utah, Escalante-Paria, Duchesne, and Southeastern Utah watersheds.

RESERVOIRS

Reservoir storage is at 67% of capacity statewide compared to 81% last year.

STREAMFLOW

March 1 streamflow forecasts for April to July are for well-below normal runoff, with extremely low flow predicted for some locations. Forecast values range from 20% of average for the Rockport Reservoir inflow to 81% for the Smiths Fork.

Bear / 86%

W eb er Og & de 7 n 6% Northeastern Uinta 75%

T P o J r 8 o Duchesne o o 8 v e 7 r % d o l 8 70% e a % & n

h c Lowe t r Sevier i P 83% % Price & n 7 a 7 San Rafael S 67%

r ie Beav v Dirty Devil er e S 88% 75% r % e 7 p 7 p U

Southeastern Utah 67% Escalante 74% Southwestern Utah 62%

Sources: Esri, USGS, NOAA, Sourc%es: Eosrif, GNarmoinr, mUSGaSl, NPS Statewide Snow Water Equivalent < 50% 50 - 69% As of March 1, 2021: 70 - 89% 77% of Normal Snow Water Equivalent 90 - 109% 110 - 129%

0 10 20 40 60 80 100 130 - 149% Miles > 150% Bear / 79%

W eb er Og & de 6 n 9% Northeastern Uinta 78%

T P o J r 7 o Duchesne o o 2 v e 7 r % d o 64% l 2 e a % & n

h c Lowe t r Sevier i P 80% % Price & n 9 a 6 San Rafael S 66%

r ie Beav v Dirty Devil er e S 75% 70% r % e 7 p 6 p U

Southeastern Utah 65% Escalante 61% Southwestern Utah 56%

Sources: Esri, USGS, NOAA, Sourc%es: Eosrif, GNarmoinr, mUSGaSl, NPS Statewide Precipitation < 50% 50 - 69% As of March 1, 2021: 70 - 89% 70% of Normal Precipitation 90 - 109% 111% of Normal Precipitation Last Month 110 - 129%

0 10 20 40 60 80 100 130 - 149% Miles > 150% March 1, 2021 Surface Water Supply Index Feb EOM* Years with similiar Basin or Region APR-JUL Forecast Storage + Forecast Percentile SWSI# Storage SWSI KAF ^ KAF ^ KAF ^ % Bear River 807.7 49.0 856.7 55 0.4 01, 13, 88, 81 Woodruff Narrows 25.4 66.0 91.4 14 -2.98 13, 03, 90, 89 Little Bear 12.1 13.0 25.1 20 -2.5 01, 00, 14, 03 Ogden River 60.1 67.0 127.1 43 -0.6 91, 89, 20, 10 Weber River 252.2 72.0 324.2 5 -3.77 04, 13, 15, 03 Provo River 991.7 63.0 1054.7 39 -0.89 02, 14, 18, 13 Western Uinta 163.8 66.0 229.8 26 -1.98 07, 12, 08, 94 Eastern Uinta 23.9 37.5 61.4 7 -3.57 14, 02, 18, 13 Blacks Fork 5.0 62.0 67.0 15 -2.88 04, 01, 00, 12 Smiths Fork 3.8 19.0 22.8 21 -2.46 12, 89, 18, 03 Price River 34.4 18.0 52.4 33 -1.39 94, 01, 07, 10 Joe's Valley 38.2 27.0 65.2 12 -3.17 90, 91, 03, 89 Ferron Creek 4.3 19.0 23.3 7 -3.57 18, 13, 02, 90 Moab 0.6 2.3 2.9 14 -2.98 18, 90, 89, 12 Upper Sevier 61.9 44.0 105.9 21 -2.38 18, 15, 09, 08 San Pitch 0.0 11.3 11.3 12 -3.17 15, 16, 13, 90 Lower Sevier 93.5 71.0 164.5 33 -1.39 14, 20, 90, 94 Beaver River 8.1 16.4 24.5 17 -2.78 03, 07, 00, 08 Virgin River 32.0 26.9 58.8 17 -2.78 15, 96, 13, 02 *EOM, end of month; # SWSI, surface water supply index; ^KAF, thousand acre-feet. What is a Surface Water Supply Index?

The Surface Water Supply Index (SWSI) is a predictive indicator of total surface water availability within a watershed for the spring and summer water use seasons. The index is calculated by combining pre-runoff reservoir storage (carryover) with forecasts of spring and summer streamflow which are based on current snowpack and other hydrologic variables. SWSI values are scaled from +4.1 (abundant supply) to -4.1 (extremely dry) with a value of zero (0) indicating median water supply as compared to historical analysis. SWSI's are calculated in this fashion to be consistent with other hydroclimatic indicators such as the Palmer Drought Index and the Precipitation index.

Utah Snow Surveys has also chosen to display the SWSI value as well as a PERCENT CHANCE OF NON-EXCEEDANCE. While this is a cumbersome name, it has the simplest application. It can be best thought of as a scale of 1 to 99 with 1 being the drought of record (driest possible conditions) and 99 being the flood of record (wettest possible conditions) and a value of 50 representing average conditions. This rating scale is a percentile rating as well, for example a SWSI of 75% means that this years water supply is greater than 75% of all historical events and that only 25% of the time has it been exceeded. Conversely a SWSI of 10% means that 90% of historical events have been greater than this one and that only 10% have had less total water supply. This scale is comparable between basins: a SWSI of 50% means the same relative ranking on watershed A as it does on watershed B, which may not be strictly true of the +4 to -4 scale.

For more information on the SWSI go to: www.ut.nrcs.usda.gov/snow/ on the water supply page. The entire period of historical record for reservoir storage and streamflow is available. Statewide Utah March 1, 2021

Snowpack in Utah is below normal at 77% of normal, compared to 104% last year. Precipitation in February was above average at 111%, which brings the seasonal accumulation (Oct-Feb) to 70% of average. Soil moisture is at 29% compared to 45% last year. Reservoir storage is at 67% of capacity, compared to 81% last year. Forecast streamflow volumes range from 20% to 81% of average.

Reservoir Storage

Statewide Bear River Basin Duchesne Basin Lower Sevier

Price Basin

Provo Basin Southwestern Utah Upper Sevier Weber & Ogden Basins

Previous Year % Capacity Current % Capacity

SNOTEL Data Bear River Basin March 1, 2021

Snowpack in the Bear River Basin is below normal at 86% of normal, compared to 107% last year. Precipitation in February was much above average at 145%, which brings the seasonal accumulation (Oct-Feb) to 79% of average. Soil moisture is at 49% compared to 63% last year. Reservoir storage is at 62% of capacity, compared to 71% last year. Forecast streamflow volumes range from 27% to 82% of average. The surface water supply index is 55% for the Bear River, 14% for the Woodruff Narrows, 20% for the Little Bear.

Reservoir Storage

BEAR LAKE

HYRUM

PORCUPINE

WOODRUFF CREEK

WOODRUFF NARROWS

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:15:35 AM Bear River Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast Forecast 90% 70% 50% 30% 10% 30yr Avg Bear River % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Bear R nr UT-WY State Line APR-JUL 30 52 66 59% 81 103 112 APR-SEP 34 58 74 60% 91 115 123 Bear R ab Resv nr Woodruff APR-JUL 3.6 9.7 42 35% 74 110 121 APR-SEP 2.6 16.6 45 35% 81 133 128 Big Ck nr Randolph APR-JUL 0.11 0.46 1.5 39% 2.5 4.3 3.8 Smiths Fk nr Border APR-JUL 44 61 72 81% 83 100 89 APR-SEP 53 72 85 82% 98 117 104 Bear R bl Stewart Dam MAR-JUL 0 13.5 60 29% 106 175 205 MAR-SEP 0 14.1 67 29% 120 198 230 APR-JUL 0 9.2 49 27% 96 164 183 APR-SEP 0 8.2 55 27% 108 186 205 Little Bear at Paradise APR-JUL 1.35 3.9 13 29% 22 36 45 Logan R nr Logan APR-JUL 40 57 69 62% 81 98 111 Blacksmith Fk nr Hyrum APR-JUL 2.6 11.5 20 47% 29 41 43

1) 90% and 10% exceedance probabilities are actually 95% and 5% 2) Forecasts are for unimpaired flows. Actual flow will be dependent on management of upstream reservoirs and diversions 3) Median value used in place of average

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Bear Lake 807.7 908.2 594.1 1302.0 Hyrum Reservoir 12.1 9.8 11.2 15.3 Porcupine Reservoir 7.5 11.3 7.0 11.3 Woodruff Creek 2.7 2.0 2.6 4.0 Woodruff Narrows Reservoir 25.4 52.7 31.6 57.3 Basin-wide Total 855.5 984.0 646.5 1389.9 # of reservoirs 5 5 5 5

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Upper Bear 4 77% 104% Middle Bear 7 96% 111% Lower Bear 3 79% 88% Logan River 7 82% 108% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Bear River 807.74 49.00 856.74 55 0.4 01, 13, 88, 81 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Bear River Surface Water Supply Index 1800

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600 ThousandAcreFeet 400

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Water Year

Storage (KAF) Streamflow (KAF) March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Little Bear 12.14 13.00 25.14 20 -2.5 01, 00, 14, 03 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Little Bear Surface Water Supply Index 140

120

100

ThousandAcreFeet 40

Water Year

Storage (KAF) Streamflow (KAF) March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Woodruff Narrows 25.44 66.00 91.44 14 -2.98 13, 03, 90, 89 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Woodruff Narrows Surface Water Supply Index 300

250

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150

100 ThousandAcreFeet

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 30 40 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Bear River Basin SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 86% of Normal SWE )" 90 - 109% 79% of Normal Precipitation )" 110 - 129% 145% of Normal Precipitation Last Month )" 130 - 149% 49% Saturation Soil Moisture )" > 150% Bear River Basin )" No Normal Weber & Ogden River Basins March 1, 2021

Snowpack in the Weber & Ogden River Basins is below normal at 76% of normal, compared to 99% last year. Precipitation in February was above average at 121%, which brings the seasonal accumulation (Oct-Feb) to 69% of average. Soil moisture is at 37% compared to 61% last year. Reservoir storage is at 57% of capacity, compared to 79% last year. Forecast streamflow volumes range from 22% to 57% of average. The surface water supply index is 43% for the Ogden River, 5% for the Weber River.

Reservoir Storage

CAUSEY

EAST CANYON

ECHO

LOST CREEK

PINEVIEW

ROCKPORT

SMITH AND MOREHOUSE

WILLARD BAY

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:15:39 AM Weber Ogden Rivers Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Weber Ogden Rivers % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Smith & Morehouse Resv Inflow APR-JUL 5.1 9.7 12.8 38% 16 21 34 Weber R nr Oakley APR-JUL 11.3 28 39 33% 50 66 117 Rockport Reservoir Inflow APR-JUL 3.7 8.8 24 20% 39 61 123 Chalk Ck at Coalville APR-JUL 0.82 2.3 11 27% 19.7 32 41 Weber R nr Coalville APR-JUL 5 14.8 33 26% 51 77 126 Echo Reservoir Inflow APR-JUL 5 14.9 36 22% 69 117 166 Lost Ck Reservoir Inflow APR-JUL 0.36 1.04 4 33% 7 11.3 12.1 East Canyon Ck nr Jeremy Ranch APR-JUL 0.02 0.61 4.7 31% 8.8 14.8 15.2 East Canyon Ck nr Morgan APR-JUL 0.28 1.89 8.4 30% 14.9 24 28 Weber R at Gateway APR-JUL 9.4 22 72 23% 155 275 315 SF Ogden R nr Huntsville APR-JUL 7.2 19.9 29 52% 37 50 56 Pineview Reservoir Inflow APR-JUL 12.5 45 67 57% 89 121 118 Wheeler Ck nr Huntsville APR-JUL 0.32 1.58 2.9 46% 4.2 6.2 6.3 Centerville Ck APR-JUL 0.07 0.25 0.63 47% 1 1.43 1.35

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Causey Reservoir 4.0 6.2 3.2 7.1 East Canyon Reservoir 32.2 42.6 34.9 49.5 Echo Reservoir 27.5 58.1 47.9 73.9 Lost Creek Reservoir 14.8 17.4 12.2 22.5 Pineview Reservoir 56.2 63.3 53.0 110.1 Rockport Reservoir 33.7 50.4 34.8 60.9 Willard Bay 141.6 190.7 138.4 215.0 Smith And Morehouse Reservoir 2.4 5.2 3.6 8.1 Basin-wide Total 312.3 433.9 328.0 547.1 # of reservoirs 8 8 8 8

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Upper Weber 10 72% 100% Lower Weber 7 79% 106% Ogden River 5 79% 91% Lost Creek 3 81% 104% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Ogden River 60.14 67.00 127.14 43 -0.6 91, 89, 20, 10 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Ogden River Surface Water Supply Index 400

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250

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150 ThousandAcreFeet 100

Water Year

Storage (KAF) Streamflow (KAF) March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Weber River 252.19 72.00 324.19 5 -3.77 04, 13, 15, 03 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Weber River Surface Water Supply Index 1200

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800

600

400 ThousandAcreFeet

200

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Weber & Ogden River Basins SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 76% of Normal SWE )" 90 - 109% 69% of Normal Precipitation )" 110 - 129% 121% of Normal Precipitation Last Month )" 130 - 149% 37% Saturation Soil Moisture )" > 150% Weber & Ogden River Basins )" No Normal Provo & Jordan River Basins March 1, 2021

Snowpack in the Provo & Jordan River Basins is below normal at 78% of normal, compared to 105% last year. Precipitation in February was above average at 121%, which brings the seasonal accumulation (Oct-Feb) to 72% of average. Soil moisture is at 25% compared to 44% last year. Reservoir storage is at 79% of capacity, compared to 90% last year. Forecast streamflow volumes range from 29% to 75% of average. The surface water supply index is 39% for the Provo River.

Reservoir Storage

DEER CREEK

JORDANELLE

STRAWBERRY

UPPER STILLWATER

UTAH LAKE

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:15:42 AM Provo Jordan Rivers Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Provo Jordan Rivers % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Provo R at Woodland APR-JUL 34 50 63 63% 77 100 100 Provo R at Hailstone APR-JUL 33 50 63 58% 78 103 108 Provo R bl Deer Ck Dam APR-JUL 13.9 37 52 45% 67 90 116 Spanish Fk at Castilla APR-JUL 12 24 34 49% 46 67 69 American Fk ab Upper Powerplant APR-JUL 0.96 4.1 9.3 29% 14.5 22 32 Utah Lake Inflow APR-JUL 2.4 34 93 35% 197 460 265 W Canyon Ck nr Cedar Fort APR-JUL 0.11 0.49 0.9 51% 1.31 1.91 1.76 Little Cottonwood Ck nr SLC APR-JUL 18.2 23 27 71% 31 38 38 Big Cottonwood Ck nr SLC APR-JUL 14.8 22 27 75% 32 39 36 Mill Ck nr SLC APR-JUL 0.45 2.7 4.2 66% 5.7 7.9 6.4 Parleys Ck nr SLC APR-JUL 0.7 5.9 9.4 66% 12.9 18.1 14.2 Dell Fk nr SLC APR-JUL 1.19 2.1 2.9 53% 3.9 5.8 5.5 Emigration Ck nr SLC APR-JUL 0.74 1.53 2.3 58% 3.3 5.2 4 City Ck nr SLC APR-JUL 0.62 3.2 5 65% 6.8 9.4 7.7 Salt Ck at Nephi APR-JUL 2.1 3.2 4.2 44% 5.6 8.4 9.5

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Deer Creek Reservoir 119.2 142.6 112.0 149.7 Strawberry Reservoir 925.3 961.1 660.5 1105.9 Utah Lake 661.7 829.3 785.8 870.9 Jordanelle Reservoir 210.8 262.0 239.4 314.0 Basin-wide Total 1917.0 2195.0 1797.7 2440.5 # of reservoirs 4 4 4 4

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Provo River 7 67% 92% Jordan River 16 85% 118% Utah Lake 13 71% 98% Spanish Fork River 6 68% 84% Six Creeks 15 84% 116% Cottonwood Creeks 7 80% 115% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Provo River 991.72 63.00 1054.72 39 -0.89 02, 14, 18, 13 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Provo River Surface Water Supply Index 1600

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600 ThousandAcreFeet 400

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Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Provo & Jordan River Basins SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 78% of Normal SWE )" 90 - 109% 72% of Normal Precipitation )" 110 - 129% 121% of Normal Precipitation Last Month )" 130 - 149% 25% Saturation Soil Moisture )" > 150% Provo & Jordan River Basins )" No Normal Tooele Valley & West Desert Basins March 1, 2021

Snowpack in the Tooele Valley & West Desert Basins is below normal at 88% of normal, compared to 114% last year. Precipitation in February was above average at 130%, which brings the seasonal accumulation (Oct-Feb) to 72% of average. Soil moisture is at 18% compared to 23% last year. Reservoir storage is at 51% of capacity, compared to 75% last year. Forecast streamflow volumes range from 51% to 74% of average.

Reservoir Storage

GRANTSVILLE

SETTLEMENT CANYON

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:15:44 AM Tooele Valley West Desert Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Tooele Valley West Desert % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF)

Vernon Ck nr Vernon APR-JUL 0.35 0.61 0.85 61% 1.14 1.69 1.39 S Willow Ck nr Grantsville APR-JUL 1.44 1.92 2.3 74% 2.7 3.4 3.1 Dunn Ck nr Park Valley APR-JUL 0.74 1.49 2 69% 2.5 3.3 2.9 W Canyon Ck nr Cedar Fort APR-JUL 0.11 0.49 0.9 51% 1.31 1.91 1.76

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Settlement Canyon Reservoir 0.5 0.7 0.7 1.0 Grantsville Reservoir 1.7 2.6 2.1 3.3 Basin-wide Total 2.2 3.2 2.8 4.3 # of reservoirs 2 2 2 2

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Tooele Valley 3 90% 137% Raft River 5 94% 117% Deep Creek 0 Northwestern Utah 3 83% 113% / 0 5 10 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Tooele Valley & West Desert Basins SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 88% of Normal SWE )" 90 - 109% 72% of Normal Precipitation )" 110 - 129% 130% of Normal Precipitation Last Month )" 130 - 149% 18% Saturation Soil Moisture )" > 150% Tooele Valley & West Desert Basins )" No Normal Northeastern Uinta Basin March 1, 2021

Snowpack in the Northeastern Uinta Basin is below normal at 75% of normal, compared to 121% last year. Precipitation in February was near average at 99%, which brings the seasonal accumulation (Oct-Feb) to 78% of average. Soil moisture is at 27% compared to 46% last year. Reservoir storage is at 83% of capacity, compared to 85% last year. Forecast streamflow volumes range from 52% to 72% of average. The surface water supply index is 15% for the Blacks Fork, 21% for the Smiths Creek.

Reservoir Storage

FLAMING GORGE

MEEKS CABIN

STATELINE

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:15:47 AM Northeastern Uintas Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Northeastern Uintas % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Blacks Fk nr Robertson APR-JUL 33 50 62 72% 74 91 86 EF of Smiths Fork nr Robertson 2 APR-JUL 11 15.5 19 70% 23 29 27 Flaming Gorge Reservoir Inflow 2 APR-JUL 139 400 580 59% 760 1020 980 Ashley Ck nr Vernal APR-JUL 11.8 19.6 26 52% 33 46 50 Big Brush Ck ab Red Fleet Reservoir APR-JUL 5.7 8.9 11.5 55% 14.4 19.4 21

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Flaming Gorge Reservoir 3145.1 3225.3 3014.0 3749.0 Stateline Reservoir 3.8 5.7 5.2 12.0 Meeks Cabin Reservoir 5.0 11.0 11.9 32.5 Basin-wide Total 3153.9 3242.1 3031.1 3793.5 # of reservoirs 3 3 3 3

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Blacks Fork River 3 89% 115% Upper Green 2 78% 151% Ashley Brush Creeks 4 54% 102% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Blacks Fork 5.02 62.00 67.02 15 -2.88 04, 01, 00, 12 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Blacks Fork Surface Water Supply Index 200 180 160 140 120 100 80

ThousandAcreFeet 60 40 20 0

Water Year

Storage (KAF) Streamflow (KAF) March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Smiths Fork 3.82 19.00 22.82 21 -2.46 12, 89, 18, 03 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Smiths Fork Surface Water Supply Index 80

30 ThousandAcreFeet 20

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 30 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Northeastern Uinta Basin SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 75% of Normal SWE )" 90 - 109% 78% of Normal Precipitation )" 110 - 129% 99% of Normal Precipitation Last Month )" 130 - 149% 27% Saturation Soil Moisture )" > 150% Northeastern Uinta Basin )" No Normal Duchesne River Basin March 1, 2021

Snowpack in the Duchesne River Basin is below average at 70% of normal, compared to 103% last year. Precipitation in February was below average at 81%, which brings the seasonal accumulation (Oct-Feb) to 64% of average. Soil moisture is at 18% compared to 34% last year. Reservoir storage is at 80% of capacity, compared to 85% last year. Forecast streamflow volumes range from 30% to 55% of average. The surface water supply index is 26% for the Western Uintas, 7% for the Eastern Uintas.

Reservoir Storage

BIG SAND WASH CURRANT CREEK

MOON LAKE

RED FLEET

STARVATION

STEINAKER

STRAWBERRY

UPPER STILLWATER

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:15:49 AM Duchesne River Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Duchesne River % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) WF Duchesne R at VAT Diversion APR-JUL 3.6 6 8 43% 10.3 14.1 18.6 Duchesne R nr Tabiona 2 APR-JUL 34 47 58 54% 70 89 108 Upper Stillwater Reservoir Inflow2 APR-JUL 25 33 40 54% 47 59 74 Rock Ck nr Mountain Home 2 APR-JUL 30 40 48 55% 56 70 88 Duchesne R ab Knight Diversion 2 APR-JUL 64 87 104 53% 123 154 195 Currant Ck Reservoir Inflow2 APR-JUL 3.2 5.8 8 40% 10.6 15 20 Strawberry R nr Soldier Springs 2 APR-JUL 6.7 15.2 23 40% 32 49 58 Strawberry R nr Duchesne 2 APR-JUL 13.7 30 45 40% 63 94 112 Lake Fork R ab Moon Lake Reservoir APR-JUL 16.8 25 32 52% 40 52 61 Lake Fk R Bl Moon Lk nr Mountain Home2 APR-JUL 19.7 28 34 52% 41 52 66 Yellowstone R nr Altonah APR-JUL 17.4 26 33 54% 41 53 61 Duchesne R at Myton 2 APR-JUL 39 77 110 33% 149 220 330 Uinta R bl Powerplant Diversion nr Neola2 APR-JUL 12.5 25 35 47% 47 69 74 Whiterocks R nr Whiterocks APR-JUL 11 19.2 26 48% 34 47 54 Duchesne R nr Randlett 2 APR-JUL 29 73 115 30% 166 260 385 Ashley Ck nr Vernal APR-JUL 11.8 19.6 26 52% 33 46 50 Big Brush Ck ab Red Fleet Reservoir APR-JUL 5.7 8.9 11.5 55% 14.4 19.4 21

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Steinaker Reservoir 7.7 8.7 23.1 33.4 Red Fleet Reservoir 16.1 21.1 18.3 25.7 Big Sand Wash Reservoir 15.6 24.8 25.7 Upper Stillwater Reservoir 3.8 19.4 7.6 32.5 Starvation Reservoir 150.7 151.9 144.5 164.1 Moon Lake Reservoir 13.1 28.9 26.3 35.8 Currant Creek Reservoir 14.7 14.6 14.8 15.5 Strawberry Reservoir 925.3 961.1 660.5 1105.9 Basin-wide Total 1131.4 1205.7 895.1 1412.9 # of reservoirs 7 7 7 7

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Strawberry River 5 67% 97% Lakefork Yellowstone Rivers 7 73% 106% Uinta Whiterocks River 2 59% 100% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Eastern Uinta 23.86 37.50 61.36 7 -3.57 14, 02, 18, 13 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Eastern Uinta Surface Water Supply Index 200 180 160 140 120 100 80

ThousandAcreFeet 60 40 20 0

Water Year

Storage (KAF) Streamflow (KAF) March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Western Uinta 163.79 66.00 229.79 26 -1.98 07, 12, 08, 94 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Western Uinta Surface Water Supply Index 400

350

300

250

200

150 ThousandAcreFeet 100

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 30 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Duchesne River Basin SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 70% of Normal SWE )" 90 - 109% 64% of Normal Precipitation )" 110 - 129% 81% of Normal Precipitation Last Month )" 130 - 149% 18% Saturation Soil Moisture )" > 150% Duchesne River Basin )" No Normal San Pitch River Basin March 1, 2021

Snowpack in the San Pitch River Basin is below normal at 77% of normal, compared to 102% last year. Precipitation in February was above average at 123%, which brings the seasonal accumulation (Oct-Feb) to 69% of average. Soil moisture is at 37% compared to 55% last year. Reservoir storage is at 0% of capacity, compared to 60% last year. The forecast streamflow volumes range from 68% to 72% of average. The surface water supply index is 12% for the San Pitch.

Reservoir Storage

GUNNISON RESERVOIR

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:16:01 AM San Pitch River Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg San Pitch River % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Manti Ck bl Dugway Ck nr Manti APR-JUL 6.3 9.1 11.3 68% 13.7 17.7 16.7 Sevier R nr Gunnison APR-JUL 19.5 50 71 72% 92 122 99

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Gunnison Reservoir 0.0 12.2 13.0 20.3 Basin-wide Total 12.2 13.0 20.3 # of reservoirs 1 1 1 1

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Upper San Pitch 3 62% 95% Lower San Pitch 6 78% 99% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % San Pitch 0.00 11.30 11.30 12 -3.17 15, 16, 13, 90 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

San Pitch Surface Water Supply Index 70

ThousandAcreFeet 20

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS San Pitch River Basin SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 77% of Normal SWE )" 90 - 109% 69% of Normal Precipitation )" 110 - 129% 123% of Normal Precipitation Last Month )" 130 - 149% 37% Saturation Soil Moisture )" > 150% San Pitch River Basin )" No Normal Price & San Rafael Basins March 1, 2021

Snowpack in the Price & San Rafael Basins is much below normal at 67% of normal, compared to 96% last year. Precipitation in February was near average at 105%, which brings the seasonal accumulation (Oct-Feb) to 66% of average. Soil moisture is at 28% compared to 41% last year. Reservoir storage is at 55% of capacity, compared to 75% last year. Forecast streamflow volumes range from 37% to 53% of average. The surface water supply index is 33% for the Price River, 12% for Joe's Valley, 7% for Ferron Creek.

Reservoir Storage

CLEVELAND LAKE

HUNTINGTON NORTH

JOES VALLEY

MILLER FLAT

MILLSITE

SCOFIELD

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:15:51 AM Price San Rafael Rivers Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Price San Rafael Rivers % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF)

Fish Ck ab Reservoir nr Scofield APR-JUL 6.8 11.3 15 50% 19.2 26 30 Price R nr Scofield Reservoir2 APR-JUL 6.3 12.5 18 44% 24 36 41 White R bl Tabbyune Creek APR-JUL 2.1 4.1 5.8 37% 7.8 11.4 15.5 Green R at Green River, UT 2 APR-JUL 800 1220 1550 52% 1930 2550 2960 Electric Lake Inflow 2 APR-JUL 2.1 3.8 5.2 39% 6.9 9.7 13.3 Huntington Ck nr Huntington 2 APR-JUL 11 16.4 21 53% 25 33 40 Joes Valley Reservoir Inflow2 APR-JUL 14 21 27 48% 33 44 56 Ferron Ck (Upper Station) nr Ferron APR-JUL 11.6 15.8 19 50% 23 28 38

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Joes Valley Reservoir 38.2 47.8 40.0 61.6 Millsite 4.3 7.5 10.2 16.7 Huntington North Reservoir 4.1 4.2 3.3 4.2 Cleveland Lake 1.1 4.9 5.4 Miller Flat Reservoir 1.4 1.3 5.2 Scofield Reservoir 34.4 51.7 30.7 65.8 Basin-wide Total 81.0 111.3 84.2 148.3 # of reservoirs 4 4 4 4

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Price River 4 67% 95% San Rafael 6 65% 98% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Price River 34.37 18.00 52.37 33 -1.39 94, 01, 07, 10 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Price River Surface Water Supply Index 180

160

140

120

100

60 ThousandAcreFeet 40

Water Year

Storage (KAF) Streamflow (KAF) March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Ferron Creek 4.26 19.00 23.26 7 -3.57 18, 13, 02, 90 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Ferron Creek Surface Water Supply Index 120

100

40 ThousandAcreFeet

Water Year

Storage (KAF) Streamflow (KAF) March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Joe's Valley 38.23 27.00 65.23 12 -3.17 90, 91, 03, 89 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Joe's Valley Surface Water Supply Index 200 180 160 140 120 100 80

ThousandAcreFeet 60 40 20 0

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 30 40 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Price & San Rafael Basins SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 67% of Normal SWE )" 90 - 109% 66% of Normal Precipitation )" 110 - 129% 105% of Normal Precipitation Last Month )" 130 - 149% 28% Saturation Soil Moisture )" > 150% Price & San Rafael Basins )" No Normal Lower Sevier Basin March 1, 2021

Snowpack in the Lower Sevier Basin is below normal at 83% of normal, compared to 109% last year. Precipitation in February was much above average at 156%, which brings the seasonal accumulation (Oct-Feb) to 80% of average. Soil moisture is at 16% compared to 39% last year. Reservoir storage is at 40% of capacity, compared to 60% last year. The forecast streamflow volume for the Sevier R nr Gunnison is 72% of average. The surface water supply index is 33% for the Lower Sevier.

Reservoir Storage

SEVIER BRIDGE

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:16:03 AM Lower Sevier Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Lower Sevier % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Chicken Ck nr Levan

Sevier R nr Gunnison APR-JUL 19.5 50 71 72% 92 122 99 Oak Ck nr Oak City

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Sevier Bridge Reservoir 93.5 140.7 169.0 236.0 Basin-wide Total 93.5 140.7 169.0 236.0 # of reservoirs 1 1 1 1

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Lower Sevier 1 83% 109% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Lower Sevier 93.47 71.00 164.47 33 -1.39 14, 20, 90, 94 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Lower Sevier Surface Water Supply Index 900

800

700

600

500

400

300 ThousandAcreFeet 200

100

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 30 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Lower Sevier Basin SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 83% of Normal SWE )" 90 - 109% 80% of Normal Precipitation )" 110 - 129% 156% of Normal Precipitation Last Month )" 130 - 149% 16% Saturation Soil Moisture )" > 150% Lower Sevier Basin )" No Normal Upper Sevier Basin March 1, 2021

Snowpack in the Upper Sevier Basin is below normal at 77% of normal, compared to 108% last year. Precipitation in February was near average at 98%, which brings the seasonal accumulation (Oct-Feb) to 67% of average. Soil moisture is at 26% compared to 41% last year. Reservoir storage is at 53% of capacity, compared to 89% last year. Forecast streamflow volumes range from 53% to 67% of average. The surface water supply index is 21% for the Upper Sevier.

Reservoir Storage

OTTER CREEK

PANGUITCH LAKE

PIUTE

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:15:58 AM Upper Sevier Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Upper Sevier % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Mammoth Ck nr Hatch APR-JUL 8.2 12.4 16 59% 20 28 27 Sevier R at Hatch APR-JUL 6.5 19.3 28 58% 37 50 48 EF Sevier R nr Kingston APR-JUL 2.1 13.3 23 66% 32 46 35 Sevier R nr Kingston APR-JUL 1.98 3.9 19 58% 31 50 33 Sevier R bl Piute Dam APR-JUL 3.3 23 44 67% 61 84 66 Clear Ck ab Diversions nr Sevier APR-JUL 2.1 8.9 13.6 65% 18.3 25 21 Salina Ck nr Emery APR-JUL -2.1 1.66 4.2 53% 6.7 10.5 7.9

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Piute Reservoir 31.5 63.8 53.6 71.8 Otter Creek Reservoir 30.3 46.7 38.6 52.5 Panguitch Lake 15.7 20.0 13.7 22.3 Basin-wide Total 77.6 130.5 105.9 146.6 # of reservoirs 3 3 3 3

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Upper Sevier 12 77% 108% Middle Sevier 8 84% 95% East Fork Sevier River 5 71% 119% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Upper Sevier 61.87 44.00 105.87 21 -2.38 18, 15, 09, 08 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Upper Sevier Surface Water Supply Index 350

300

250

200

150

ThousandAcre Feet 100

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 30 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Upper Sevier Basin SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 77% of Normal SWE )" 90 - 109% 67% of Normal Precipitation )" 110 - 129% 98% of Normal Precipitation Last Month )" 130 - 149% 26% Saturation Soil Moisture )" > 150% Upper Sevier Basin )" No Normal Southeastern Utah March 1, 2021

Snowpack in the Southeastern Utah is much below normal at 67% of normal, compared to 107% last year. Precipitation in February was below average at 70%, which brings the seasonal accumulation (Oct-Feb) to 65% of average. Soil moisture is at 19% compared to 36% last year. Reservoir storage is at 27% of capacity, compared to 87% last year. Forecast streamflow volumes range from 22% to 53% of average. The surface water supply index is 14% for Moab.

Reservoir Storage

KEN'S LAKE

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:15:56 AM Southeastern Utah Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Southeastern Utah % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Mill Ck at Sheley Tunnel nr Moab APR-JUL 1.04 1.73 2.3 53% 3 4.1 4.3 South Ck ab Resv nr Monticello MAR-JUL 0.04 0.13 0.24 22% 0.41 0.77 1.09 Colorado R nr Cisco 2 APR-JUL 1340 1850 2240 52% 2670 3370 4280 San Juan R near Bluff 2 APR-JUL 215 345 450 41% 570 770 1100

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Ken's Lake 0.6 2.0 1.3 2.3 Basin-wide Total 0.6 2.0 1.3 2.3 # of reservoirs 1 1 1 1

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Lasal Mountains 1 70% 89% Lower San Juan 2 73% 122% Lower Green 2 66% 116% Henry Mountains 0 March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Moab 0.62 2.30 2.92 14 -2.98 18, 90, 89, 12 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Moab Surface Water Supply Index 14

ThousandAcreFeet 4

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 30 40 50 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Southeastern Utah SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 67% of Normal SWE )" 90 - 109% 65% of Normal Precipitation )" 110 - 129% 70% of Normal Precipitation Last Month )" 130 - 149% 19% Saturation Soil Moisture )" > 150% Southeastern Utah )" No Normal Dirty Devil Basin March 1, 2021

Snowpack in the Dirty Devil Basin is below normal at 88% of normal, compared to 105% last year. Precipitation in February was much above average at 139%, which brings the seasonal accumulation (Oct-Feb) to 75% of average. Soil moisture is at 26% compared to 35% last year. Forecast streamflow volumes range from 48% to 71% of average.

SNOTEL Data Data Current as of: 3/4/2021 10:15:54 AM Dirty Devil Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Dirty Devil % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Muddy Ck nr Emery APR-JUL 4.4 7.2 9.5 48% 12.1 16.6 19.9 Seven Mile Ck nr Fish Lake APR-JUL 2.5 4 5.2 71% 6.6 8.9 7.3

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Muddy Creek 3 81% 100% Fremont River 4 90% 111% Henry Mountains 0 / 0 5 10 20 30 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Dirty Devil Basin SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 88% of Normal SWE )" 90 - 109% 75% of Normal Precipitation )" 110 - 129% 139% of Normal Precipitation Last Month )" 130 - 149% 26% Saturation Soil Moisture )" > 150% Dirty Devil Basin )" No Normal Escalante River Basin March 1, 2021

Snowpack in the Escalante River Basin is below normal at 74% of normal, compared to 116% last year. Precipitation in February was much below average at 68%, which brings the seasonal accumulation (Oct-Feb) to 61% of average. Soil moisture is at 13% compared to 19% last year. The forecast streamflow volume for Pine Creek is 63% of average.

SNOTEL Data Data Current as of: 3/4/2021 10:16:08 AM Escalante River Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Escalante River % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Pine Ck nr Escalante APR-JUL 0.41 0.98 1.5 63% 2.1 3.3 2.4

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Escalante River 3 74% 116% Paria River 3 79% 127% / 0 5 10 20 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Escalante River Basin SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 74% of Normal SWE )" 90 - 109% 61% of Normal Precipitation )" 110 - 129% 68% of Normal Precipitation Last Month )" 130 - 149% 13% Saturation Soil Moisture )" > 150% Escalante River Basin )" No Normal Beaver River Basin March 1, 2021

Snowpack in the Beaver River Basin is below normal at 75% of normal, compared to 86% last year. Precipitation in February was above average at 129%, which brings the seasonal accumulation (Oct-Feb) to 70% of average. Soil moisture is at 13% compared to 27% last year. Reservoir storage is at 35% of capacity, compared to 91% last year. The forecast streamflow volume for the Beaver River is 63% of average. The surface water supply index is 17% for the Beaver River.

Reservoir Storage

MINERSVILLE RESERVOIR

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:16:05 AM Beaver River Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Beaver River % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF) Beaver R nr Beaver APR-JUL 1.92 10.5 16.4 63% 22 31 26

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Minersville Reservoir 8.1 21.1 15.1 23.3 Basin-wide Total 8.1 21.1 15.1 23.3 # of reservoirs 1 1 1 1

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Beaver River 3 75% 86% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Beaver River 8.09 16.40 24.49 17 -2.78 03, 07, 00, 08 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Beaver River Surface Water Supply Index 100 90 80 70 60 50 40

ThousandAcreFeet 30 20 10 0

Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Beaver River Basin SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 75% of Normal SWE )" 90 - 109% 70% of Normal Precipitation )" 110 - 129% 129% of Normal Precipitation Last Month )" 130 - 149% 13% Saturation Soil Moisture )" > 150% Beaver River Basin )" No Normal Southwestern Utah March 1, 2021

Snowpack in the Southwestern Utah is much below normal at 62% of normal, compared to 107% last year. Precipitation in February was much below average at 41%, which brings the seasonal accumulation (Oct-Feb) to 56% of average. Soil moisture is at 24% compared to 44% last year. Reservoir storage is at 38% of capacity, compared to 49% last year. Forecast streamflow volumes range from 26% to 45% of average. The surface water supply index is 17% for the Virgin River.

Reservoir Storage

GUNLOCK

KOLOB

LAKE POWELL

LOWER ENTERPRISE

QUAIL CREEK

SAND HOLLOW

UPPER ENTERPRISE

Previous Year % Capacity Current % Capacity

SNOTEL Data Data Current as of: 3/4/2021 10:16:10 AM Southwestern Utah Streamflow Forecasts - March 1, 2021 Forecast Exceedance Probabilities for Risk Assessment Chance that actual volume will exceed forecast

Forecast 90% 70% 50% 30% 10% 30yr Avg Southwestern Utah % Avg Period (KAF) (KAF) (KAF) (KAF) (KAF) (KAF)

Lake Powell Inflow 2 APR-JUL 1520 2450 3200 45% 4050 5490 7160 Virgin R nr Hurricane APR-JUL 1.89 5.7 16.4 26% 35 62 63 Virgin R at Virgin APR-JUL 8.6 17.5 25 43% 35 51 58 Santa Clara R nr Pine Valley APR-JUL 0.34 1.09 1.85 37% 2.8 4.6 5 Coal Ck nr Cedar City APR-JUL 2.9 5.2 7.2 37% 9.6 13.6 19.4

Reservoir Storage Current Last Year Average Capacity End of February, 2021 (KAF) (KAF) (KAF) (KAF) Lake Powell 9225.6 12011.5 17055.0 24322.0 Lower Enterprise 0.9 0.8 1.0 2.6 Upper Enterprise 3.5 5.4 3.9 10.0 Kolob Reservoir 2.8 3.8 5.6 Gunlock 4.9 7.8 6.7 10.4 Sand Hollow Reservoir 48.5 49.5 50.0 Quail Creek 27.1 31.1 30.0 40.0 Basin-wide Total 9262.0 12056.6 17096.6 24385.0 # of reservoirs 5 5 5 5

Watershed Snowpack Analysis Last Year # of Sites % Median March 1, 2021 % Median Upper Virgin 8 60% 102% Lower Virgin 2 46% 85% Coal Parowan Creeks 4 67% 109% March 1, 2021 Surface Water Supply Index

Basin or Region Feb EOM* Storage APR-JUL Forecast Storage + Forecast Percentile SWSI# Years with similiar SWSI ^ ^ ^ KAF KAF KAF % Virgin River 31.98 26.85 58.83 17 -2.78 15, 96, 13, 02 *EOM, end of month; #SWSI, Surface Water Supply Index; ^KAF, thousand acre-feet.

Virgin River Surface Water Supply Index 300

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Water Year

Storage (KAF) Streamflow (KAF) / 0 5 10 20 30 Miles

Sources: Esri, USGS, NOAA, Sources: Esri, Garmin, USGS, NPS Southwestern Utah SNOTEL Site % of Normal )" < 50% *# Forecast Point )" 50 - 69% As of March 1, 2021: )" 70 - 89% 62% of Normal SWE )" 90 - 109% 56% of Normal Precipitation )" 110 - 129% 41% of Normal Precipitation Last Month )" 130 - 149% 24% Saturation Soil Moisture )" > 150% Southwestern Utah )" No Normal Issued by Released by

Terry Cosby Emily Fife Acting Chief State Conservationist Natural Resources Conservation Service Natural Resources Conservation Service U.S. Department of Agriculture Salt Lake City, Utah

Prepared by Snow Survey Staff: Jordan Clayton, Data Collection Officer Troy Brosten, Assistant Supervisor Kent Sutcliffe, Soil Scientist Dave Eiriksson, Hydrologist Joel Burley, Hydrologist Doug Neff, Electronic Technician

YOU MAY OBTAIN THIS PRODUCT AS WELL AS CURENT SNOW, PRECIPITATION, TEMPERATURE AND SOIL MOISTURE, RESERVOIR, SURFACE WATER SUPPLY INDEX, AND OTHER DATA BY VISITING OUR WEB SITE @: https://www.nrcs.usda.gov/wps/portal/nrcs/main/ut/snow/

Snow Survey, NRCS, USDA 245 North Jimmy Doolittle Road Salt Lake City, UT 84116 (385) 285-3118

Utah Water Supply Outlook Report Natural Resources Conservation Service Salt Lake City, UT