Sheridan County Water Supply Report


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Sheridan County Water Supply Report
 August Report

How to Use This Report

What is this report?

Instead of combing the internet and clicking a million links to learn about water supply in Sheridan County, let us do the work for you! This report compiles many trustworthy sources into an easy-to-read and access report. It includes information about streamflow, snowpack, drought, soil moisture, and precipitation for both the Tongue and Powder Rivers. This report is a one-stop shop for information that can help you be aware of water in Sheridan to make decisions for your ranch and your land.

Helpful Hints:

  • All forecasts have the word forecast underlined in the page's title.
  • Each page has a little blurb at the top that gives you some helpful information.
  • If you would like to know more about a topic, check out the sources at the bottom of the page!
  • Sources are precise and bring you as close as possible to the original source.

Table of Contents

Drought Index and Change
Drought History and Forecast
Precipitation - Tongue River
Precipitation - Powder River
Reservoir Capacity and Stream Flow
Select Stream Flow Stations
Tongue Water Supply Forecast
Powder Water Supply Forecast
Temperature and Precipitation
Temperature Forecast and Precipitation Forecast
Vegetation Drought Responses and Soil Moisture

Drought Index and Change

The U.S. Drought Monitor gives you a broad overview of the drought conditions in the US. Its strength is bringing together many ways of determining drought. It is useful as a large-scale view of drought, but local drought resiliency efforts are not considered.

Current Drought Monitor

Most of Sheridan County is in D0, Abnormally Dry. The Bighorn Mountains and foothills are experiencing drought conditions. 

Change in Drought Monitor

While drought conditions did not improve in Sheridan County, degradation was only season in the Bighorn mountains and foothills. This degradation was Class 1, which is the most minor class of degradation. 

Sources:

​https://droughtmonitor.unl.edu/Maps/MapArchive.aspx​
​https://droughtmonitor.unl.edu/Maps/ChangeMaps.aspxhttps://droughtmonitor.unl.edu/Summary.aspx​

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Drought History and Forecast

The first half of this page shows current conditions, followed by the forecast. The outlook is a prediction of

History of Drought Monitor

Drought conditions have improved compared to three months ago, when over 20% of the county was experiencing severe drought. Conditions have decreased slightly over the last week, with more of the county experiencing moderate drought.  

Forecast of Drought Monitor

Looking into August, NOAA reports: " Except for pockets of above-normal precipitation confined to eastern Colorado, southwestern Kansas, and central Nebraska, 30-day precipitation generally averaged below-normal across the Northern to Central Great Plains. A heat wave is ongoing at the end of July and these above-normal temperatures are forecast to continue into the beginning of August, which will lead to a rapid drying of topsoil."1

Sources:

​https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?fips_56033​
​https://www.drought.gov/forecasts​
1https://www.cpc.ncep.noaa.gov/products/expert_assessment/mdo_summary.php

https://www.cpc.ncep.noaa.gov/products/expert_assessment/mdo_discussion.php​
​https://droughtmonitor.unl.edu/Summary.aspx​

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Precipitation - Tongue River

These graphs represent precipitation affecting the Tongue River. Snow water equivalent (SWE) represents the amount of water contained within the snowpack when it melts.



Summary

Snow-water equivalent is at 0 inches. This is normal for this time of year. Precipitation is at 94% of median, within the normal range. It is in the 28th percentile. Although precipitation is at 94% of median, it is low enough to be just outside the 'normal' range.  

Sources:

​https://nwcc-apps.sc.egov.usda.gov/awdb/basin-plots/POR/WTEQ/assocHUCwy_8/tongue.html​
​https://nwcc-apps.sc.egov.usda.gov/awdb/basin-plots/POR/PREC/assocHUCwy_8/tongue.htm​

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Precipitation - Powder River

These graphs represent precipitation affecting the Powder River watershed. Snow water equivalent represents the amount of water contained within the snowpack when it melts.



Summary

Snow Water Equivalent (SWE) is at 0 inches, which is normal for this time of year.  Precipitation accumulation is at 95% of median, which is the 30th percentile. Accumulated precipitation continues to hover near the bottom end of the normal range. 

Sources:

​https://nwcc-apps.sc.egov.usda.gov/awdb/basin-plots/POR/WTEQ/assocHUCwy_8/powder.html​
​https://nwcc-apps.sc.egov.usda.gov/awdb/basin-plots/POR/PREC/assocHUCwy_8/powder.html​

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Reservoir Capacity and Stream Flow

The total capacity of reservoirs and current water storage includes inactive storage below the outlet.

Lake DeSmet

As of August 1, Lake DeSmet has a total of 206,272 acre-feet in storage, a decrease of approximately 4,000 acre-feet since July.

Reservoir Total Storage (Acre-ft) Current Storage (Acre-ft) Percentage of Total Capacity (%)
Bighorn 4,624 2,786
Cross Creek 824 461
Dome Lake No. 1 1,506 1,282
Kearney Lake 6,324 4,504
Park Lake 10,362 8,541
Sawmill 1,275 1,275

Tongue River Reservoir

Water levels decreased over the last month from 79,147 acre-feet to 67,510 acre-feet. The reservoir is 85.4% full.


Reservoir Level



This graph displays the real time data of the Tongue River Reservoir. This data remains provisional until it is officially reviewed due to variables that can affect the gages. These include but are not limited to algal and aquatic growth, sediment movement, malfunction of recording equipment, and back water from ice or debris such as log jams.

Sources:

Lake DeSmet Operating Department at lakedesmet@johnsoncowy.us​
​https://seoflow.wyo.gov/Data/Map/Parameter/Total%20Storage/Location/Identifier/Interval/Latest​
​https://gis.dnrc.mt.gov/apps/stage/gage-report/location/3f087fe86bde421f857dfedff4e40e93/1680476400000-1683154740000​

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Select Stream Flow Stations

These graphs give context to stream flow percentile classes. The selected USGS stream gauges are on the stateline with Montana, being the downstream end of the Tongue and Powder within our region. The flow represent average 7-day flows. The vertical axis is logarithmic meaning it goes up by 10x for each major tick mark.



Tongue River Border Station Stream Flow

Streamflow has generally remained in the "Normal" range, or 25- 75th percentile, as we move into summer. Streamflow has moved from near the top of the normal range in June to near the bottom of the normal range. 

Powder River Stream Flow

Streamflow is in the "Normal" range or 25-75th percentile. Streamflow has decreased and moved from near the top of the normal range to nearing the bottom of the normal range. 


Sources:

​https://waterwatch.usgs.gov/index.php?id=mv01d​
​https://waterwatch.usgs.gov/?id=wwchart_sitedur&ofmt=plot_mvbg&site_no=06306300​
​https://waterwatch.usgs.gov/?id=wwchart_sitedur&ofmt=plot_mvbg&site_no=06324500​

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Tongue Water Supply Forecast

This chart takes a while to understand but holds valuable information. The exceed value is percent chance that flows exceed will exceed a given volume. For instance, 90% exceedance means there is a 90% chance it will be above and a 10% chance it will be below


Tongue River Water Supply

All sites in the Tongue River watershed have above a 70% chance of exceeding median flows for both the short-term and long-term forecast. We can expect flows to be higher than normal, with a 50% chance of exceeding 110-120% of median at most forecast points. This is the most recent forecast.

Sources:

​https://www.nrcs.usda.gov/wps/portal/wcc/home/waterSupply/waterSupplyForecasts/​

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Powder Water Supply Forecast

This chart takes a while to understand but holds valuable information. The exceed value is percent chance that flows exceed will exceed a given volume. For instance, 90% exceedance means there is a 90% chance it will be above and a 10% chance it will be below. It's still a 1/10 chance of being below.


Powder River Water Supply

The June to July and June to September forecast has above a 70% chance that flows will exceed median for most sites. Flows have a lower chance of exceeding median at the North Fork of the Powder River near Hazelton, where there is less than a 50% chance of flows exceeding median. However, elsewhere in the Powder River watershed, flows are expected to be at or higher than normal. This is the most recent forecast.

Sources:

​https://www.nrcs.usda.gov/wps/portal/wcc/home/waterSupply/waterSupplyForecasts/​

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Temperature and Precipitation

Temperature and precipitation are large drivers of changes in drought conditions. As you might expect, high temperatures and low precipitation can worsen drought conditions while low temperature and high precipitations can improve them.


Temperature Anomaly

July was slightly warmer than most years, with a temperature anomaly 1 to 2 degrees higher than usual. 

Precipitation Anomaly

The precipitation anomaly for most of Sheridan County was 0 mm, indicating normal or near normal precipitation for July compared to other years. 


Sources:

​https://www.cpc.ncep.noaa.gov/products/tanal/temp_analyses.php​
​https://www.cpc.ncep.noaa.gov/products/Global_Monsoons/American_Monsoons/NAMS_precip_monitoring.shtml2​
​https://www.cpc.ncep.noaa.gov/products/expert_assessment/mdo_discussion.php3​
​https://www.weather.gov/byz/daily_records?city=Sheridan​

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Temperature Forecast and Precipitation Forecast

https://www.cpc.ncep.noaa.gov/products/predictions/long_range/lead14/interactive/index.php Explore link above for an Interactive map that displays percentage chance above and below normal for any point in US


Temperature

Sheridan has 50-60% probability of temperature above normal for July. This follows a band of expected heat that is most extreme in western Wyoming and Utah. 

Precipitation

Sheridan County has a 33-40% probability of precipitation being below normal in August, indicating a hot and dry month ahead. 


Sources:

​https://www.cpc.ncep.noaa.gov/​
​https://www.cpc.ncep.noaa.gov/products/predictions/long_range/lead14/interactive/index.php –Interactive with percentages​
​https://www.cpc.ncep.noaa.gov/products/expert_assessment/mdo_discussion.php​

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Vegetation Drought Responses and Soil Moisture

The graphs below are two ways of visualizing on-ground conditions. The vegetation Drought Response Index (Vegdri) uses a satellite to estimate vegetative stress. Soil moisture is helpful when looking at many things. Soil acts as a bank for moisture and can buffer drought degradation or improvement. It is also the water that plants have available to them so is linked to vegetative stress.


Vegetation Drought Response

Vegetation across the county is showing pre-drought to moderate or severe drought stress. The more severe drought stress is seen on the western side of the county. 

Soil Moisture

Soil moisture percentile decreases west to east, with mountain soils showing the highest soil moisture percentile at 40 to 60%(grey) and declining to 30 to 40% (yellow), and as low as 20 to 30% (tan) on the east side of the county. This is despite the most vegetative stress still being seen on the western side of the county.


Sources:

​https://vegdri.unl.edu/Home/VegDRIQuad.aspx?WY,2​
​https://www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/US/Soilmst/Soilmst.shtml​
​http://www.wrds.uwyo.edu/Soil/SM-Ptile-Current.htm​

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Additional Resources

These are the broad sources we got information from. These websites are trustworthy and are reliable sources for additional information. In the future we hope to add more source for additional information.