Southern California, Arizona, Utah, Colorado, and New Mexico are experiencing severe drought conditions, but far western Nevada and parts of northern California are not. In fact, the map on the US Drought Monitor website currently shows that the Truckee River and Lake Tahoe basins are in the “none” category. We are however, surrounded by “abnormally dry”. Perhaps it would be safer to say we are on the cusp of drought conditions later this year. Dry conditions usually persist here from late spring into early fall. Being dry for half of the year is the norm for western Nevada – actually, most of the far western states. Nevada has the distinction of having the lowest average annual precipitation statewide – less than 10″. Much of western Nevada is even lower at 7.4″ or less average annual precipitation.
Drought Map for 3-29-2018 – On the edge of the drought the map appears to exclude the Truckee River and Tahoe Basins – at least for now.
Truckee River in Reno with flows at 2,000 CFS during the last weekend in March 2018.
For the moment, however, we can enjoy the high flows in both the Truckee River – currently above 2,500 cubic-feet-per-second (CFS). The snowpack is already melting and won’t provide runoff for anywhere near as long as we saw last year. A storm is forecast for the end of the week.
As we mentioned in our earlier post, the Federal Water Master is releasing water from Lake Tahoe today at more than 1,300 CFS (and rising as this as I write this). Lake Tahoe stands just below 6,228.6 feet in elevation. Pyramid Lake may actually be rising due to increased inflows and may now be higher than the last official reading reported at 3,802.37 feet surface elevation on February 28, 2018.
Snow is melting fast on the north-facing slopes of the Carson Range shown here at about 6,400 feet.
Most low elevation areas – below 7,000 ft – are already snow free such as here on the Jones-White’s Creek Trail.
The Carson River is currently flowing at nearly 1,000 CFS (April 2, 2018). Diversions from the Carson River for agriculture have already begun. Diversions to agriculture place a huge burden on the Carson River and cause it to be dry by early summer most years before it gets to Lahontan Reservoir. When flows are low on the Carson River and Lahontan Reservoir has storage available, then the Truckee-Carson Irrigation District (TCID) diverts water from the Truckee River (it uses the entire flow of the Carson River that is available). Diverted Truckee River water flows through the “Truckee Canal” and dumped out at Lahontan Reservoir just upstream of the Dam. Water diverted by TCID never gets to Pyramid Lake; the loss of water caused Pyramid to fall 80 feet in elevation since diversions began 113 years ago.
Carson River at Mexican Dam at Silver Saddle Park in Carson City, March 28, 2018.
The greatly improved snowpack will improve runoff in the Truckee River and flows to Pyramid Lake this spring. The snow and rain in March did come too little and too late to push us to an average water year, however. How quickly drought conditions on the river will return depends on how rapidly the spring warms up and whether we get additional storms – never to be counted on – during the early spring. Precipitation since October 1 (the beginning of the water year) remains below normal, too, but better than the snowpack. Snow water in the end-of-season snowpack appears to be diminishing year after year, especially the lower elevation snowpack.
Washoe Lake is full currently with a much healthier snowpack in the nearby Carson Range. (Slide Mountain as viewed across Washoe Lake from Deadman’s Canyon in the State Park.)
The Tahoe and Truckee River basin snowpack water content remains significantly better today than in February. Although the official water content gets counted on April 1, the numbers won’t change too much. So for March 29, the median water equivalent in the snowpack stands at 78% in the Lake Tahoe basin and 83% in the Truckee River basin. However, total precipitation (rain and snow water equivalent) for this water year is better at 97% and 91% of normal. The Carson River basin has more water in the snowpack at 88% which matches the total precipitation percentage – 88%. Overall, the Carson River’s watershed is higher elevation than the Truckee River’s which may account for the precipitation tracking overall precipitation.
Lake Tahoe stands at 6228.6 feet – just 6″ below its maximum legal elevation and 5.6 feet above its outlet rim. The Lake Tahoe dam controls flows out of Lake Tahoe into the Truckee River. The Lake will soon see an increase in runoff from the melting snowpack. How fast it rises will be based on flows into the Truckee River by the Federal Water Master’s office – the administrator of the Federal Court decree that governs water in the Truckee River for both California and Nevada – as well as the temperatures this spring that determine how quickly the snowpack melts. In an average water year, Lake Tahoe sees a rise in elevation of about 3 feet over spring and early summer. Truckee River flows are running above the long-term average now at more than 2,000 cubic-feet-per-second (CFS) at Pyramid Lake.
Truckee River in Reno with flows at 2,000 CFS during the last weekend in March 2018.
Pyramid Lake may see a moderate rise if flows in the Truckee River remain high for most of the spring and diversions to the Newlands Project are small. As of February 28, 2018 Pyramid’s elevation was 3,802.37 feet elevation. Pyramid Lake’s historic elevation before the Newlands Project was built was 3,880 feet in elevation. Last year saw a significant rise in the Lake’s elevation – some 10 feet. With a less than stellar water year for 2017-18, however, Pyramid Lake’s elevation will most likely decline again. The highest elevation for Pyramid Lake in the last 25 years occurred in 1999 when it reached an elevation of 3,817 feet.
Water flows from Lake Tahoe into the Truckee River increased dramatically in the past 7 days. How long these flows from Tahoe last will be based, in part, on how rapidly the snow pack melts.
Flows from Lake Tahoe have jumped from 50 to 900 CFS in the last 7 days.
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.
A new storm is approaching the Tahoe and Truckee River basins on the first day of spring. Will it bring significant rain and snow to the region to help make up for the dry Dec-Jan-Feb?
As impressive as it looks, it could end up producing much more precipitation on the western side of the Sierra and along the pacific coast than here on the eastern slope of the Sierra. Heaviest precipitation forecast for the Reno area is late Wednesday into Thursday morning.
Storm approaching on first day of spring, Tuesday, 3-20-18
Storms over the past weeks have improved the snowpack, but is this anticipated storm going to be a true “Miracle March” by making up for meager snowfall and rainfall during the winter? Lake Tahoe has gained nearly a half-foot of water in the last 4 weeks and now stands at a water elevation of 6,228.25 feet – 5.25 feet above its natural rim.
Tahoe elevation has risen by nearly a half foot in the last several weeks.
The Tahoe Basin and the Truckee River basin stand at 63 and 67 percent of average for snow-water equivalent. Runoff for the remainder of the year for the Truckee River will be determined by how fast the snow melts and if there are more storms to add significantly to the snow pack. While we had a great snow pack last year, it is important for our rivers and lakes to have back-to-back good flow years to promote recovery of the river environment and needed water for Pyramid Lake that has suffered from years of drought. All of us will benefit from a big storm that brings our snowpack to closer to the long-term average.
Snow water equivalent as of March 20, 2018 for Tahoe, Truckee River, and Carson River basins
A concrete walled Truckee River trickles through downtown Reno in late 2014.
The report attempts to map 300,000 miles of rivers and streams in the 11 western states and show the human impacts made to their flows and floodplains. The interactive map allows anyone to zoom in on any western state location and identify the extent of damage to large rivers and small rivers and headwater streams in mountain ranges from the Rockies across the Great Basin to the Sierra and Cascades. The map colors range from deep blue to fire red depicting a range from near natural condition to extremely altered or unnatural condition for either stream flow restriction or floodplain modification. Some states have far more severely modified streams and rivers than others. Overall, however, the west appears more red-colored than blue-colored with surprisingly small streams high in mountains suffering from flow reduction and floodplain modification. While the report offers a valuable tool to look at how our rivers and streams are suffering, we’ve discovered that reporting on the Truckee River flows below Reno-Sparks underestimates the severe dewatering of the river at Derby Dam.
A cautionary note: It could be that the report underestimates damage from flow reductions in other states if the Truckee River flow diversions were missed.
The report shows Nevada ranked 2nd in the major rivers and 3rd in the smaller rivers categories that suffer from flow restrictions, 94% and 31% respectively. Utah ranks first in reduced flows in major rivers at 96%. I used the “Disappearing Rivers” information to develop the bar graphs, presented below, ranking states by flow restrictions and floodplain alterations for major rivers.
Ranking of flow restrictions for major rivers by state (based on information in “Disappearing Rivers” Report-DLG)
Ranking of floodplain alteration for major rivers by state (based on information in “Disappearing Rivers” Report-DLG)
Likewise, the report also shows Nevada 2nd in modification to major river floodplains at 73% and smaller river floodplains at 51%. Colorado ranks first in major river floodplain modification at 77%.
Reducing river flows and developing river floodplains can eventually kill riverine ecosystems by eliminating the riparian forest that grows along the stream, warming the stream from reduced flows, eliminating cold water fish and invertebrates that live in the stream as well as increasing pollution and reducing recreation.
The report separates the rivers and streams into categories: headwater streams with less than 6 cubic-feet-per-second (CFS), smaller rivers and streams between 6 CFS and 163 CFS, and major rivers with more than 163 CFS.² In Nevada, the Truckee, Carson, and Walker Rivers that originate in California’s Sierra Nevada all had historical average flows greater than 163 CFS. The Humboldt River which is entirely within Nevada also had historical average flows greater than 163 CFS. Today, the Truckee River is a mere trickle at Pyramid Lake when US Bureau of Reclamation diversions at Derby Dam take as much as three-fourths of its flow to farms in Lahontan Valley; the Carson River is essentially dry during many summer and autumn seasons before it reaches Lahontan Reservoir due to upstream diversions; and the Walker is often completely dry – sometimes for years – before it reaches Walker Lake. The Humboldt River, likewise, is more frequently dried out before it reaches Rye Patch Reservoir upstream of Lovelock.
Any measure of flowing water can take a little getting used to, but remember, the flow in a river or stream is measured by how much water (volume) is moving downstream over a period of time. It can be in gallons-per-minute or cubic-feet-per-second or acre-feet per year. The US standard way to measure flowing water in a river is CFS or cubic-feet-per-second.¹
Lower Truckee River flow restriction much worse than shown in “Disappearing Rivers” Interactive Map
The Disappearing Rivers analysis shows the lower portion of the Truckee River as having only 8% flow restriction in the lower River between Derby Dam and Pyramid Lake. Unfortunately, this is not accurate. The screen capture from the interactive tool shows the diversion at Derby Dam, but inaccurately says it is only 2,500 acre-feet. It isn’t clear where that number comes from.
Disappearing Rivers: screen capture of river tool’s depiction of flow restriction of the Truckee River below Derby Dam is incorrect.
In fact, tens of thousands of acre-feet of water are diverted from the Truckee River most years and hundreds of thousands have been diverted in the 21st century alone. So, the representation in the online tool for the Truckee River flow restriction downstream of Derby Dam³ isn’t correct. The problem appears to be that the data used to model the restricted flow caused by Derby Dam doesn’t accurately reflect how much water is diverted on average over an entire year. Derby Dam itself, doesn’t store much water, but the effect of its diversion is the most significant loss on the entire Truckee River below Lake Tahoe.
Example display from the Disappearing Rivers Project interactive map
Despite the problem I’ve identified where the Disappearing Rivers Map underestimates restricted flows for the lower Truckee River below Derby Dam, the tool remains valuable to show how our rivers have suffered from loss of flows and modification to the floodplains in Nevada and throughout the 11 western states. The tool affords even the casual user a stark window into the damage inflicted on our rivers from continually taking too much floodplain land for development and too much water from river flow.
In broad terms, the summary provided for the state of Nevada is sobering:
“In Nevada, 53 percent of all rivers are altered. That’s equal to 3,593 unnatural river miles— enough to cross the state more than 11 times. Of the 11 Western states in the Disappearing Rivers analysis, Nevada had the 5th most altered rivers in the West. When broken down by size, 96 percent of all major rivers, 64 percent of all smaller streams and rivers, and 36 percent of all headwaters are altered.”
How can we reverse continual losses of river flows and floodplain lands? Can society embrace increasing natural river flows and restoration of floodplain lands? Increasing population and climate change is making the job of fixing what ails our rivers harder. This report makes clear that in a little over a century, we’ve diverted at least 61% of the flow of our western rivers and negatively modified 63% of river floodplains. And, additional impacts to river flows and floodplains occur daily from the direct effect of development but also from climate change which is making the west warmer – and possibly drier as well. Few people want to have a dry Truckee River surrounded by parking lots and warehouses, but our representatives in federal, state and local governments seem to be taking us to just such a future. It is time to ask politicians to find ways to reduce the amount of water we take from our rivers and aquifers, protect our remaining floodplains, and restore our overdeveloped floodplains.
Restored oxbow of the Truckee River at the Nature Conservancy’s McCarran Ranch.
There have been some restoration successes on the Truckee River over the past couple of decades. We have seen the restoration of several floodplain reaches of the Truckee River below Reno from Lockwood to the McCarran Ranch. The Nature Conservancy’s McCarran Ranch represents one of the earliest successful efforts to show how a degraded river can be transformed with a vibrant riparian corridor of wetlands and forest that can support spawning trout and a valuable recreational fishery and recreation. The Truckee River Water Quality Agreement between the Cities of Reno and Sparks and the Pyramid lake Tribe called for the cities to purchase water rights for the Truckee River to increase river flows during low flow. The Cities have purchased more than 11,000 acre-feet of water which can mean the difference between having a dry river and a wet one. The water purchased stays in the river all the way to Pyramid Lake.
Flows in the Truckee River can be greatly improved by reducing diversions from the river, improving farm practices, and increasing water conservation in cities and towns along the river.
Now is the time to make sure our rivers will not continue to disappear.
¹ [For people who like to think in gallons, there are 7.48 gallons in a cubic foot. For example, during February 2018, the Truckee River has been running between 350 and 450 CFS through downtown Reno or between 2,618 and 3,366 gallons per second. You can check out the flow of the Truckee River every day in the RGJ newspaper on the weather page or look on the TROA website under daily report]
² 6 CFS for one year is 11.9 acre-feet or 3.88 million gallons; 163 CFS over a year is 188 thousand acre-feet or 38.5 billion gallons. To offset the effect of evaporation from Lake Tahoe requires about 350,000 acre-feet of water each year above what flows out into the Truckee River; likewise, it takes more than 400,000 acre-feet of water each year to maintain Pyramid Lake’s water level.
³ Derby Dam on the Truckee River is the largest diversion on the Truckee River. The dam, completed in 1905, was the first project of the US Bureau of Reclamation called the Newlands Reclamation Project. While most people in Reno and Sparks have never heard of the project, it is responsible for the greatly reduced flows of the lower Truckee River downstream of the cities. The dam allows Truckee River water to be put into a 112 year-old canal, permanently removed from the Truckee River basin, and sent to farms on the lower Carson River’s Lahontan Valley. Once diversions began, Pyramid Lake and the lower Truckee River were sent into a steep decline. Flows in the Pyramid Lake Paiute Tribe Reservation‘s portion of the Truckee River were reduced to just a trickle. Any time during many years (flood years being the exception), a substantial portion of the water in the Truckee River as it flows through Reno-Sparks will end up in Lahontan Valley and not Pyramid Lake due to the diversions at Derby Dam. The dam at Lake Tahoe is also part of the Newlands Reclamation Project and the water stored in Lake Tahoe by the dam benefits farmers in Lahontan Valley. The Lake Tahoe dam can store over 700,000 acre-feet of water by raising Tahoe’s water elevation by up to 6.1 feet.
US Bureau of Reclamation’s Derby Dam on the Truckee River diverts water to Lahontan Valley
US Bureau of Reclamation’s Lake Tahoe Dam at the outlet to the Truckee River