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.
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
A bill, AB 193, that just had a Nevada Assembly Committee hearing last Tuesday, would mandate that the Truckee Meadows Water Authority (TMWA) add fluoride to our community’s high quality drinking water. The bill should come again before the Assembly Natural Resources Committee; reports are that the committee members appeared favorable to the Legislation. The legislators appear willing to overrule the voters of Washoe County who rejected water fluoridation by a 58% to 42% vote in 2002. Continue reading →
Despite the rains of October in the central Sierra, Tahoe today is still 3.6″ below its rim and no water flows to the Truckee River from the Lake. Most of the Truckee River flow comes from tributaries downstream of Lake Tahoe’s outlet including the Little Truckee River, its largest tributary. It is, however, likely that Tahoe will rise above its rim in the coming weeks as winter weather approaches. Filling Lake Tahoe to its maximum elevation would raise the current level more than 6 feet and require at least a 200 percent water year or double the long-term average annual precipitation of snow and rain.
Lake Tahoe elevation week ending 12-05-2016
October was a wet month in Reno with two storms that each produced over an inch of rain. It was extremely welcome after a long and very dry summer and early autumn. The storms resulted in record October rainfall for some places in the central Sierra and Lake Tahoe. Temperatures remained warmer than “normal”, however, until late November when it finally cooled off. Mt Rose Ski area on the Mt Rose Highway is reporting 13″ of snow at the lodge of natural and artificial snow and 25″ at the 9,800 foot level as I write this. Squaw Valley-Alpine Meadows Ski Resort in California reports a base of 28″ and anticipates up to 2 feet of snow from a series of storms predicted to arrive Wednesday a stay into Saturday. News of the wet October have made a hoped for wet winter in the central Sierra after last year’s dismal “El Niño” palpable. [Find an SFGATE report on the October rainfall/snowfall here.]
The US Drought Monitor is still showing Reno in the Moderate to Severe drought category despite the recent rains, but soil moisture conditions have improved as you go north toward Oregon. California mostly remains in drought with a large portion of central and southern California in the most severe drought categories. Drought conditions in Nevada have moderated with western and southern Nevada remaining in the drought categories (click map for full size).
Truckee River flow through Reno is running around 200 cubic-feet-per-second (CFS). Most of the water in the river, however, is not making it to Pyramid Lake, captured instead at Derby Dam and sent to Lahontan Reservoir through a canal.
Unfortunately, Pyramid Lake’s elevation continues to fall due significantly to the diversion of Truckee River water into the canal built by the Bureau of Reclamation in 1905 as its very first project. Water is taken out of the Truckee and sent through an unlined canal from Derby diversion dam on the Truckee all the way to Lahontan Dam on the Carson River. Since the beginning of the drought in 2000, Pyramid Lake has fallen approximately 27 feet in elevation exposing large land areas previously covered by water including shrinking the Lake on its south end to puddles near the mouth of the river. Most of the loss of water to Pyramid Lake is due to diversions to the Newlands Project, however, rather than the drought itself. (More on this later)
Derby Dam on the Truckee River diverts Truckee River water to the Carson River for the Newlands Irrigation Project starting in 1905.
The Truckee Canal diversions have resulted in the loss of Winnemucca Lake in the valley adjacent to Pyramid Lake and the approximately 80 foot drop in elevation of Pyramid Lake itself since the early 1900s. This amounts to an approximately 8 million acre-foot water deficit for Pyramid Lake, the largest body of water entirely within Nevada or, in other words, represents nearly two decades worth of the average flow of the Truckee River that Pyramid Lake never received.
Pyramid Lake benefits from high precipitation years because of reduced diversions from the river when flows are high. During the drought starting in 2000 there have only been two periods of significant flows to Pyramid Lake which raised its level over the previous year. (click to see photo comparison at full size)
Pyramid at Pyramid Lake changes over recent decade and a half are dramatic
Will this year produce snow and rain that will finally raise Pyramid Lake’s level again and restore the flows to the Truckee River?
Click the either of the images below to see them full size.
The recent rain in the northern Sierra and western Nevada was certainly welcome.
I just saw a Facebook post declaring that “11 billion gallons of water added to Lake Tahoe …”. Yes, Tahoe did rise about 3″, so its elevation today is about 6,222.75′ but still 3″ below its rim. So by the Facebook post’s reckoning, there remains an 11 billion gallon deficit.
Lake Tahoe Surface Elevation October 19, 2016
To be sure, the water year is just 3 weeks old and the 3 day rainstorm was a good start to the fall and winter season. Will we get a double or triple precipitation and snowpack year? We would need that and a lot more to make up for the 16 year drought the entire southwest has experienced.
While we can hope for a record-setting snowpack this winter, hope is not going to solve our continuing water crisis. We need to recognize the very real possibility that the average annual precipitation of the 20th century is less – perhaps far less – in the 21st century. The first sixteen years of this century have produced snowpack runoff resulting in only about 70% of the 20th century’s average river flows in the Truckee River. Expecting an end to the lower flows of the Truckee River is sticking our heads in the sand.