The timing between rainfall events stresses plants throughout the region. The decrease in moisture leads to more intense fires and dried up vegetation needed for wildlife and agriculture alike.
The research was led by University of Arizona climate scientist Fangyue Zhang. The reduction in drought busting rainfall across the southwest is consistent with climate models forecasting decreased moisture as the overall atmosphere warms due to human-caused greenhouse gas increases.
“Human activity is driving climate change.” said Colm Sweeney of NOAA’s Global Monitoring Laboratory this Wednesday according to an article in the USA Today which continued: “…the level of carbon dioxide (CO2) in the Earth’s atmosphere is now higher than it has been in at least 3.6 million years.”
Droughts appear to be lasting longer as the active winter pattern of Pacific storms shift north more frequently. This year in California and western Nevada, only one significant storm in January upped the percentage of the meager snowpack. Ultimately, the snowpack topped out around 68% for the Tahoe-Truckee River by April 1, but runoff will be less than 40% of the average due to the extremely dry soils throughout the Sierra and Nevada.
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.
Conservation and drought management ranked high by 90% of respondents to TMWA’s (Truckee Meadows Water Authority) survey of topics of importance to be addressed in the 2020-2040 TMWA Plan 5 year update. And, as before, TMWA talks generally about conservation but has no definitive goals and no new actions to achieve water efficiency to reduce per capita demand for its customers.
TMWA’s update, like the previous plan, doesn’t look to water efficiency instead calling for “enhanced conservation” by its customers only during drought. TMWA’s “Enhanced conservation” asks customers to reduce water use by 10% during level “2” to “4” droughts for between 3 months to a maximum of 5 months. In a level 1 drought or non-drought, TMWA’s plan update calls for “standard conservation”. But standard conservation offers no incentives, strategies or goals to reduce per person water use and appears to rely exclusively on an even-odd address, 3 days per week outdoor watering. TMWA has no plan to implement programs to help its customers be more water efficient over the next 20 years of the plan during all conditions. Hardly forward looking for a desert community with less than 7″ average annual precipitation, long, hot, dry summers, and rising temperatures year-after-year.
This year Reno saw just 3.81 inches of precipitation in the form of rain and snow since October 1, 2019 – over 10 months. And, Reno’s summer temperatures are hot and likely for overall average annual temperature to approach or even top those of the past. Indeed, we live in a desert and need to be efficient and conserve the little water the region has to support people and the environment.
A Chart in TMWA’s plan update shows that for the past five years water use in its service area has been right around 150 gallons per person per day (GPD). That’s more than many other western cities including Las Vegas where customer water use has declined to 120 GPD. And, Las Vegas expects to continue to lower the GPD through its water efficiency programs. TMWA should be doing the same to lower its need for expensive engineering solutions and new groundwater sources.
Too often water runs down the gutter from over-watering and inefficient or broken outdoor sprinkler systems. Once water is running down the gutter it will eventually end back up in the Truckee River with contaminants of all kinds – discarded waste and oil being common. Water waste becomes more common with ineffective incentives for customers to conserve. People-unfriendly, grass-fronted roads in business districts send water spraying into adjacent streets. These water wasteful spaces offer little to the public and could and should be replaced with appropriate water conserving landscapes, instead. With proper water efficiency incentives adopted, TMWA’s plan update could encourage appropriate low-water landscaping that offers more interesting plantings that offer more shade and function. TMWA needs a plan update that identifies implementing better options for customers to save water and lower overall demand.
The 2020-2040 TMWA Plan update doesn’t contain any new initiatives or changes to its water pricing structure. While TMWA’s website promotes the plan as an call to action, the plan update contains no new direction regarding water use.
Of the customer insights collected so far, the top concerns are related to two topics: population growth and extreme climate variation. TMWA’s approach to these issues are woven throughout this plan.
TMWA, however, continues its past approach of drilling wells, diverting more water, and pumping water underground just like its previous plan. Other cities have consistently seen the error in this approach and have found customer friendly ways to reduce demand and delay or eliminate the need for expensive new water infrastructure. Further, TMWA’s own projections show that its approach will lead to shortages under climate change scenarios. Nevertheless, the plan essentially ignores these results saying that the problem will only occur in-the-future and outside of the planning horizon. Such an approach lacks credibility and puts the entire plan in doubt.
The Truckee River watershed saw more rain than snow this year. So, this year appears to continue the trend of at least the last decade as rain replaces snow – especially at lower elevations. The maps show just how significant the effect is as we approach the end of the first month of spring. Many sites in the Truckee River basin (including the Tahoe basin) are reporting 101% of the longterm average for precipitation. The picture is different for snow water equivalent, however. Snow water equivalent (the amount of water in the snow pack) is almost or well below the longterm average for this date for sites at lower elevations. You have to go to the highest elevation sites to see average snow water equivalent conditions.
In the graphic below, the blue dots on the left represent sites where total precipitation is 101% and the white sites represent 100% of the long-term average. On the right the 3 sites (between 6400′-7700′) in red have 0% of snow water left; the orange sites have 50% of snow water left compared to the long-term average. Only the site at Big Meadow (8235′) shows 101% of snow water left and one site at Heavenly Valley (8500′) shows 100% of snow water left – both high elevation sites. Click on the graphic to see full size. Or check out the site yourself here.
NRCS 4-24-2018 – Total Precipitation vs. Snow Water Equivalent for water year to date
If the trend continues as expected, there will be very little snow left to melt in the late spring and early summer. When snow disappears earlier, natural stream flow of tributaries and the Truckee River itself decrease. Less natural stream flow often results in additional releases from reservoirs or increased ground water pumping because of our long, dry summers. Ultimately, it will negatively affect recreation and fish and wildlife that depend on water in the Truckee River.
Rain over a two day period in Reno is always a rare event. Even less common is a spring equinox atmospheric river storm that drops nearly an inch of rain at the airport in Reno. I recorded 1.75″ of rain in NW Reno from March 20 to 22 while temperatures during the storm never dropped below 42ºF. While the storm was relatively warm and produced mostly rain below 6,000 feet, the snowpack in the Lake Tahoe and the Truckee River basins saw a significant boost. Flows in the Truckee River on Thursday afternoon surged to 4,000 cubic-feet-per-second (CFS) from 500 CFS earlier in the week. If you didn’t get down to the river, check out the video from Whitewater Park at Wingfield Park in downtown Reno yesterday.
The NRCS is now reporting a significant improvement to the area snowpack. In February the snowpack was in the 30 percent of average range. As of today (3/23/18) reports show the snowpack in the Lake Tahoe basin is 77% of the average and the Truckee River basin stands at 80% for snow-water equivalent. The Carson River is at 88%.
The National Weather Service forecasts another colder (but less wet) storm is heading into the Tahoe and Truckee basins late today and continuing into Sunday. It remains to be seen if the new anticipated storm adds significantly to the snowpack. Forecasts for next week show no precipitation with temperatures rising into the mid-60s.
Eastern Pacific circulation as of 3/23/2018 mid-day. (Click for full size)
Lake Tahoe’s water surface elevation rose continuously during the spring equinox storm to stand at 6,228.6 feet. Its legal limit is 6,229.1 feet. Depending on how much runoff results from the snowpack (and any additional snow and rain), there should be good flows from Lake Tahoe into the Truckee River this spring. One thing for sure, the dismal winter up until late February has seen a significant reversal with the late season storms.
Lake Tahoe’s water surface elevation has risen nearly a foot since early in 2018. The recent storms alone resulted in a half-foot rise.