Water Outlook: NRCS Here to Help Navigate Water Availability Through Snow Survey and Farm Bill Programs By Jeff Anderson, Nevada NRCS Water Supply Specialist and Dusty Jager, Nevada NRCS State Rangeland Management Specialist Each year the USDA, Natural Resource Conservation Service (NRCS) snow survey and streamflow forecasting program tracks water supply conditions to meet the needs of the public. Snowpack, precipitation, air temperature and soil moisture are monitored by the agency’s network of 90 SNOTEL (Snow Telemetry) weather stations distributed across Nevada and the eastern Sierra. Additionally, snow surveyors collect snow tube measurements at an additional 65 snow courses. These data are used by hydrologists at the NRCS National Water and Climate Center to produce seasonal streamflow forecasts to help water managers and water users plan for the coming summer. From January through May, SNOTEL data and streamflow forecasts are summarized in the Nevada Water Supply Outlook Report which seeks to inform customers how the water year is shaping up. Since 2018, this report has also included a Rangeland Conditions section produced in cooperation with the Nevada State Rangeland Management Specialist. Below are some ways the snow survey program can serve you: • Learn more about the Nevada snow survey by watching the new snow survey video: https:// www.youtube.com/watch?v=gWm5TeASLY8
• Join the Nevada Water Supply Outlook Report subscription list: https://go.usa.gov/xz5Fk • Visit NRCS Nevada Snow Survey web pages to see current conditions: go.usa.gov/xz5F8 14 MAY/JUNE 2022
• Request or attend a snowpack and water supply presentation (opportunities are noted in the Water Supply Outlook Reports) • Request a custom SNOTEL webpage or data report to meet specific needs 2022 Water Supply Conditions Summary Based on October and December measurements, water year 2022 started with a boom, but since the start of January, precipitation totals have been trending strongly towards bust. A strong, earlyseason atmospheric river in October brought record rain amounts across Nevada for the month. SNOTEL stations in the eastern Sierra basins received 5 to nearly 20 inches of precipitation in October. Other parts of northern Nevada also did well with monthly amounts of 2.5 to 7 inches being measured. November was quiet with below normal precipitation, but storms returned in December and SNOTELs in the eastern Sierra measured a record increase in snow water for the month (Fig. 1a, 1b). January 1 snowpacks in the Sierra were over 200% of median. December snow accumulation in other parts of northern Nevada did not set records but were enough to produce an above normal January 1 snowpack. Unfortunately, from New Year’s through March, the storm track has mostly bypassed Nevada. Precipitation totals from January through March ranked as the driest on record at all SNOTEL sites in the eastern Sierra. Most sites throughout the rest of northern Nevada were also either driest or second driest for the three-month period. Most basins received more precipitation in October than during all of January, February and March combined (Figures 2a, 2b). With little precipitation since the start of the calendar year, snowpack and water year precipitation percentages which were so strong on January 1 could not keep pace with normal amounts and percentages fell. Basin snow water amounts reached 67-74% of the median peak amounts in the Sierra basins, and 62-68% of the median peak for the Northern Great Basin, Humboldt Basin, Clover Valley and Franklin River Basin, and Owyhee Basin. The Snake Basin and Eastern Nevada each ended up with peak snowpacks of 78%. The Spring Mountains were the The Progressive Rancher
only part of Nevada with an above median peak snowpack this winter. Snow peaked in the Spring Mountains on January 7 at 143% of normal, which was two months earlier than normal. April first is normally when basin snowpacks peak in terms of water content, but this year all basins had already experienced significant melt by that time. April 1 snowpack percentages were just 46-66% of median this year, compared to 60-125% last year. April 1 water year precipitation percentages are higher and near normal because they include the rain that fell in October. One bright spot this water year is that soil moisture under the snow has been above normal. October rains saturated soils and that moisture got locked in when the snow fell. Moist soils should help improve runoff efficiency this spring as the snow melts. This is especially true in the Sierra where winter streamflow has remained strong. Last year snow fell on dry soils and the spring runoff was inefficient because the dry soil soaked up snowmelt. Unfortunately, snowpacks are smaller than last year, especially in the Humboldt Basin and other portions of northern Nevada, so amount of snow to melt is unlikely to produce the volume of runoff needed to meet demands. April 1 NRCS streamflow forecasts for April-July runoff are only 12-72% of the new 1991-2020 medians. To put forecasts in perspective, most April 1 50% exceedance forecast volumes rank near to below the 20th percentile of historic observed flows. If conditions continue to be dry, the 70% exceedance forecasts are more likely and those rank well below the 10th percentile in some areas. April-July flows in the Humboldt Basin could be near record minimums if dry conditions persist. A table of all April 1 streamflow forecasts is available on the Nevada Snow Survey website, https://go.usa. gov/xznxS Continue reading to find out how the NRCS’ switch from stating data as a percent of median compares to previous years when streamflow forecasts were presented as a percent of average (Fig. 3, page 16). www.progressiverancher.com
