Tag Archives: snowpack

Drought Impacts Persist into Spring 2023

Despite above average snowpack

Reno and environs continue to see above average snow and rain. The rain and snow over the last several months would seem to indicate the drought conditions over the past two years are gone or nearly so. Sure enough drought conditions have lessened (even gone away in some places), but still persist in most of Nevada, a big chunk of northern California and, unexpectedly, most or some portion of each of the other western states.

Copious snowfall in the Sierra Nevada benefits the water outlook for this summer and for the flows of western Nevada rivers – the Truckee, Carson, and Walker. River flows on the Truckee River remained below flood levels, in part, due to the below average temperatures which keep the snowpack from melting and the storage available in the upstream reservoirs.

Lake Tahoe below its rim

Lake Tahoe was 5″ below its rim this past November 30 due to the past 2 years of drought. Since December 1, 2022 Tahoe’s water surface elevation rose 2.7 feet (32.5″). How much will Tahoe’s storage increase once snow melt commences? Spring temperatures and soil conditions and wind will all play a part in determining how much of the water stored in the snowpack flows into the Lake. One thing for sure, cold temperatures experienced this year in Reno and much of the far west are unlike our more recent warm winters (more on this later).

https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?West

Drought conditions persist but improve

Drought conditions still stretch across most of Nevada (70%). However, significant improvement since last October resulted from the storms which began hitting the region over the past 5 months. Drought conditions covered 96% of Nevada at the beginning of the water year. Severe (D2) to Exceptional (D4) Drought occurred in 48% of the state. Currently, the highest categories – D3 to D4 – cover only slightly more than 2% and Severe Drought (D2) found in about 14% – a hopeful change for the conditions this spring and summer.

Drought conditions shown on the map occur even though the precipitation since last October is over 100% in most of northern Nevada. If wet conditions continue through the spring and into the beginning of summer, additional improvement may be expected.

Precipitation exceeds the 30 year average

Precipitation for the 2022-2023 Water Year through March 20, 2023

Large snowpacks this year in the Lake Tahoe and Truckee Basin are welcome to help alleviate the drought conditions experienced throughout the west and our region since 2000. Reservoir storage for the Truckee River should improve significantly. However, the western US drought may be more of a more systemic occurrence influenced significantly by Climate Change. Nowhere is this more obvious than on the Colorado River Reservoirs Lake Mead and Lake Powell currently 28% and 23% full, respectively. Conditions for those reservoirs are not expected to improve despite more than 100% snowpack in the Rocky Mountains.

(Watch for a discussion later for how storage affects the overall health of the Truckee River system.)

Tahoe’s water surface elevation elevation over the past year

Flows into the Truckee River at Tahoe City, CA stop once the elevation of Lake Tahoe drops below 6,223 feet – indicated on this graph as “3.00”. Lake Tahoe has a large surface area and around 350,000 acre-feet of water evaporate from its surface each year. Its maximum elevation is set not to exceed 6,229.1 feet.

2023 Sees Big Snow Pack – so far

March came in like a lion with several continuous days of snow. January and February snows in the Carson Range and throughout the Sierra increased an already above-average snowpack for this time of the year to 179% in the Tahoe Basin and 169% in the Truckee Basin.

The welcome snow contrasts with the dry winters for the previous two winters. With climate change making ever hotter summers the Truckee River had low flows, Sierra reservoirs shrunk, and Lake Tahoe fell nearly a half-foot below its rim for 65 days last fall and early winter.

Atmospheric Rivers helped to build the snowpack

Lake Tahoe State Park at Spooner Lake Feb 22, 2023

Rain and then snow powered first by an “atmospheric river” and then a parade of January snow storms pushed the snowpack to over 150% in the Tahoe and Truckee Basin. Storms at the beginning and end of February continued to push the snowpack up and March is continuing the trend. As I write this, it is snowing lightly in Reno. (Another possible atmospheric river arriving in a couple of days could bring rain to lower elevation snowpack with a threat of increasing localized flooding possible.)

From nearly a half foot below its rim, Lake Tahoe today stands over two feet higher. With such a large snowpack yet to melt, Tahoe is set to rise considerably more. Likewise, reservoirs on the Truckee River system have storage available as evidenced by the following table of current levels.

Plenty of storage capacity remains in Truckee River Reservoirs

Reservoir NameStorage in Acre-feetCapacity in Acre-feetCurrent Storage %Remaining Storage in Acre-feetRemaining Capacity (%)
Stampede106,788226,50047.1%119,71252.9%
Prosser9,76729,84032.7%20,07367.3%
Boca18,74840,87045.9%22,12254.1%
Donner3,4529,50036.3%6,04863.7%
Independence (TMWA)13,59717,50077.7%3,90322.3%
Lake Tahoe
† Storage		208,900744,60028.1%535,70071.9%
Total361,2521,068,810 707,558 
March 8, 2023: Truckee River Upstream Storage

Where will this winter snowpack end up? March appears set to add more to the precipitation already received. The next storm system forecast is for rain at lower elevations below 7,000 feet to start.

Lake Tahoe from Mt Rose Highway Feb 22, 2023

The NRCS reports that “[a]s of March 1 the Reno Airport has seen 38.3 inches of snowfall through March 1 which is nearly twice normal for the entire winter.” The Airport has seen at least 4.5″ of snow fall since then.

Still, the total amount of precipitation from the winters of 1982-83 and 2016-17 exceeds this winter’s precipitation – so far.

† By court decree, the dam at Tahoe City, CA at the outlet to the Truckee River can raise the level of Lake Tahoe 6.1 feet to elevation 6,229.1 feet AMSL.

Truckee River flow to peak by May 1, 2021

The National Weather Service forecast model shows the flow of the Truckee River at Floriston, CA peaking by April 27. The extremely dry soils in the Truckee River watershed at both Lake Tahoe and the Truckee Basin are contributing to the lower runoff as well as the below average snowpack this year and last year.

The actual peak in river flows could be earlier if the weather remains warmer than expected or be later if cooler and stormier weather comes in. The 10 day forecast doesn’t appear to offer much in the way of precipitation through the first part of April, however. The Carson and Walker Rivers are also expected to have peak flows early.

Currently, the snowpack is melting fast and earlier than would be indicated by historical data. With an early melting of the snow, rivers and streams will likely be well below their average flow into the first part of the summer. The Truckee River, due to upstream storage in reservoirs and Lake Tahoe, will have summer flows while the Carson and Walker Rivers will likely be dry in early summer in many locations.

The snowpack's snow water equivalent (SWE) % of average compared to the % of forecast runoff in northern NV rivers. Runoff into the Truckee River is expected to be at or below 40% of average according to this forecast from the Nat'l Weather Service in Reno.
The snowpack’s snow water equivalent (SWE) % of average compared to the % of forecast runoff in northern NV rivers. Runoff into the Truckee River is expected to be at or below 40% of average according to this forecast from the Nat’l Weather Service in Reno. (National Weather Service Forecast from the Reno, NV office presentation)
Low flows for the Truckee River are expected summer and fall 2021.