If the fish and wildlife dependent on the Truckee River and Pyramid Lake and Lake Tahoe could cheer, we’d certainly be hearing the shout-out because of this winter’s huge rain and snow events bringing near record river flows this spring. After such a long drought and long-term rain and snow deficit beginning in 2000, this year has been a celebrated event.
Is it just a wet year following a drought or are erratic swings in precipitation to be expected from Climate Change? Are having the driest year on record in 2014-15 and the wettest year on record in 2016-17 the pattern of a new “normal” for the western US?
This is a winter and spring of superlatives for Truckee River flows. Pyramid Lake has risen, so far, 9.1 feet since January 1, 2017 and on June 1 was at a water surface elevation 3,801.24 feet above sea-level. This is a tremendous benefit to the endangered cui-ui fish found only in Pyramid Lake as well as its huge Lahontan Cutthroat Trout that wow fishermen at 15 or even 20 pounds. In the last 20 years, the high water elevation measured at Pyramid Lake was 3,817.6 feet on August 17, 1999. Prior to the federal government’s 1905 Newlands irrigation project that diverted water to expand farmland in Lahontan Valley, Pyramid Lake was relatively stable at an elevation of about 3,875 feet.†
The Truckee River on June 8, 2017 flowed at 3,900 cubic-feet-per-second (CFS) or 5 times the long-term average flow on that date – higher flows only occurred once before in 1983 (which was a wet year preceeded by several wet years).
Lake Tahoe has gone from below its rim last October to rise more than 6 feet totalling 736,000 acre-feet of water with more still coming. On June 19, the water surface elevation of Lake Tahoe was just 4.8 inches below its legal maximum of 6,229.1 feet elevation. The result of the rainfall events and exceptional snowpack runoff has contributed to the large flows of the Truckee River from late winter into spring. Summer flows in the Truckee River will also be larger than seen in many years.
Another wet year could bring Pyramid Lake back to levels not seen since 1999 when Pyramid Lake’s water surface elevation was 16 feet higher than today. Flows in the Truckee River are typically higher in multiple wet years in a row when reservoirs are already full and water must be released from reservoirs like Lake Tahoe rather than stored. If the Sierra around Tahoe has a similar rain and snow-filled winter season for 2017-18, then all of the runoff would flow to Pyramid Lake resulting in a significant inflow increase to Pyramid and raising the water level of Pyramid Lake substantially more than we saw this year. But, if next winter is average or dry, then runoff to Pyramid will be substantially less and no bump in Pyramid’s water level will occur.
So, with wild swings in preciptation observed since 1997, what can we expect from the winter of 2017-18? How will climate change – read climate warming especially in the northern hemisphere – affect snowfall and rainfall that keeps the Truckee River flowing and water in our Lakes?
With President Trump’s withdrawal from the International Climate accord, it appears that, at least from the Federal Government, it is a reversal of positive action to protect the earth from the most disastrous effects of a warming world caused by burning fossil fuels. The new administration seems determined to rapidly increase use of fossil fuels and stop solar and wind and geothermal technologies from competing.
Each of us and individual states and businesses can, however, choose to reject returning to the coal-style economy of the last century which brings higher temperatures, increased evaporation and evapotranspiration, and is very likely part of the wild swings in weather world-wide, and especially concerning for the arid western US.
Meanwhile, NOAA reports that there is a 50-55% chance that there will be “neutral” conditions in the Pacific meaning no “el niño” or “la niña” is being forecast at this time. What does that mean for the upcoming winter weather? We’ll find out at the end of March 2018.
Expect the wild ride to continue.
† Under natural conditions and prior to the 1905 Newlands irrigation project, Pyramid Lake and Winnemucca Lake both received water from the Truckee River. When Pyramid Lake reached an elevation of around 3,880 feet, water would flow through a channel north of Chalk Bluff to Winnemucca Lake. Because of the Newlands irrigation project, Pyramid Lake steadily dropped and no water could flow to Winnemucca Lake. Winnemucca Lake, once a National Wildlife Refuge, dried up in 1940. Pyramid Lake is presently about 80 feet lower in elevation than its historic level. The channel to Winnemucca Lake is still visible from highway 447 as you go around Chalk Bluff. The Pyramid Lake people in the 1920s recorded the precipitous fall of Pyramid Lake by recording elevations on the famous Pyramid. The dates inscribed on the Pyramid show how quickly it shrank as diversions began. The dates of 1924, 25, 26, 27, and 28 are visible even today each showing the successive decline in the Lake’s elevation.