The Truckee River flows are up again through Reno, right?  So that water is going to Pryamid Lake, you’re thinking?  Of course, those giant cutthroat trout that folks try to catch at Pyramid Lake are getting the benefit of the water finally flowing in the river?

In reality, as the river comes up, the Truckee River is tapped by the Newlands Project.  The water diversion 15 miles east of Sparks at Derby Dam sends the Truckee’s increased flows of water through a canal to fill the reservoir on the Carson River.  Lahontan Reservoir stores water to be used by farmers in the Fallon area.  Lahontan sits outside of the Truckee River watershed and Truckee River water only reaches it through the man-made canal built 110 years ago.

The graphic which follows shows what happened between November 1st and today, December 11, 2014.  As the river flows increased starting around November 28, more and more water was taken out of the Truckee River and sent through the canal to Lahontan Reservoir.  So instead of 350 CFS flowing into Pyramid Lake today, the majority of the water is diverted to Lahontan.  Pyramid Lake receives just about 110 CFS while about 240 CFS heads to the reservoir (December 11, 2014).  [Click on the graph to see a larger version.]  No wonder that Pyramid Lake has fallen more than 25 feet during the past 14 year drought.  [See post “Just 14 years ago”]

Graphic of Truckee River flows: Pyramid Lake doesn’t benefit from increasing flows in River

The blue symbols represent Truckee River flows just below Reno at Vista, the yellow symbols flows near Pyramid Lake, and the red symbols flows in the diversion canal.  (Diversions from the Truckee River have taken the lion’s share of water during the 3 year drought.)

So rivers do flow on – except when they aren’t allowed to.

As I write this, it is raining from Monterey, CA to Redding, CA.  Rain has moved into the northern Sierra and even sprinkles of rain with strong winds in Reno.  It is 58º F, too, so it is likely to be raining in the mountains rather than snowing.   Has the weather shifted to a wet pattern that will bring significant amounts of rain and snow to benefit the Truckee River?  Has the high pressure that has come to dominate our weather gone bye-bye?  If it comes back again to dominate the weather for the far west and southwest, then what?

Winter Storm Approach on December 11, 2014 at 11:21 AM (National Weather Service Radar)

The warm and wet storm of the past 3 days has reversed Tahoe’s water decline – at least for now.  Tahoe has risen over an inch with an upward trend and now stands 4.8″ below its rim (12/4/14).  Still no water will flow into the Truckee River from the Lake, but it is better than a continual decline.  Much of the rise is likely due to water falling directly on the surface of the lake. (See my last post regarding this phenomenon.) If wet weather continues, then we can expect a much improved water situation, but whether or not we’ll see an end to the long-term drought remains in doubt.

Tahoe Elevation (6223.0 is the rim elevation and no water flows to the Truckee River if water level drops below) – current reading is between 6,222.6 and 6,222.7.

Truckee River view downstream of Center Street in Reno on 12/4/2014.

Truckee River looking upstream from Lake Street Bridge in Reno on 9/16/2014

The first ‘winter’ storm came in on Nevada’s Sesquicentennial Celebration on the evening of October 31 and was pretty much gone by the afternoon on November 1.  I was watching to see if there was a marked change in the elevation of Lake Tahoe indicating that the storm brought significant rain or snow to the Tahoe Basin itself and not just snow at the upper elevations.  The following graph illustrates why I’m disappointed with the storm’s impact on the drought.

Lake Tahoe Surface Elevation the week ending November 3, 2014

Lake Tahoe is huge covering 192 square miles (See Tahoe fast facts below).  And, its entire watershed is just 501 square miles.  What is significant about these numbers?  Lake Tahoe itself occupies 38% of its own watershed. And, precipitation either as rain or snow at lake level directly raises the level of the Lake.  Twelve inches of rain or snow, for example, over the course of a winter, falling on the surface of the lake will raise the lake’s level 12 inches even before the snow in the mountains melts and enters the lake through the lake’s many streams.

Unfortunately, the storm didn’t produce much rain or snow, apparently, at the surface of the Lake. (7″ of snow was reported at one ski area near Echo Summit on Highway 50.)  If you look closely at the above graphic, you’ll see there was a slight bump up in the elevation of the lake, but by today (Nov 3, 2014), the surface elevation has fallen lower than before the storm hit.  The lake is now 3.6 inches below its natural rim.  Until it rises above 6,223 feet in elevation no water can enter the Truckee River at the Tahoe Dam.

Still more bad news in the recent forecast maps for continued drought in the west which show California and Nevada (even Washington and Oregon) seeing more heat and less rain and snow.  Not a good combination, for sure.

Drought Outlook through January 31, 2015.

Lake Tahoe Fast Facts (from the EPA website)

• Lake Tahoe is 2 million years old
• Size of watershed: 501 sq. miles
• Lake surface area: 192 sq. miles 1,645 ft. deep
• 6,223 ft. elevation (natural rim)
• 2 states: CA, NV
• 5 counties, 1 city
• 50,000 Tahoe Basin year-round residents
• Majority of private property owners are part-time residents
• US Forest Service  and state agencies manage almost 85% of land area
• Average surface water temperatures are 68° Fahrenheit in the summer and 41° in the winter
• 63 streams feed into Lake Tahoe but only one, the Truckee River, flows out
• Approximately 3 million people visit Lake Tahoe every year
• The Lake is designated as an Outstanding National Resource Water under the Federal Clean Water Act
• Lake Tahoe is the second deepest lake in the United States
• Lake Tahoe is so deep that a single drop of water entering the Lake today will take about 650 years to find its way out

Related articles across the web

• Lake Tahoe Reaches Natural Rim
• 5 reasons to visit Lake Tahoe in the fall
• Tahoe level at 5-year low; no Truckee River flows
• Lake Tahoe Level Falls To 5-Year Low
• Tahoe level at 5-year low; no Truckee River flows
• Tahoe level at 5-year low; no Truckee River flows

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE RENO NV
1111 AM PDT THU OCT 30 2014

...FIRST WINTER STORM OF THE SEASON FOR HALLOWEEN...

.AN EARLY SEASON WINTER STORM WILL BRING MODERATE TO HEAVY SNOW
TO THE SIERRA FRIDAY EVENING INTO SATURDAY MORNING. THE MAIN
IMPACT FROM THIS STORM IS HAZARDOUS TRAVEL CONDITIONS WITH
WHITEOUT CONDITIONS AND CHAIN CONTROLS OVER THE SIERRA PASSES.
THIS STORM WILL LEAD TO THE WINTER CLOSURES FOR THE PASSES IN
ALPINE AND MONO COUNTIES.

And not a moment too soon.  Let’s hope that it is a harbinger of a very, very wet winter.  The Truckee River is a trickle through Reno at about 5% of its usual flow this time of year.  Lake Tahoe is 3 inches below its rim cutting off the Truckee River from its largest source of water.  Large reservoirs on the Truckee’s tributaries to the Truckee are near 25% capacity — or less.  Drought is not a stranger to the region to be sure.  However, this drought occurs with substantially more people – and the resulting additional demand on a dwindling resource.

While, agricultural crops can be foregone in a drought, people in cities demand water regardless of how that demand affects the river and downstream environments.  We are intolerant of “insufficient supply” as an argument for reducing our own water use.  Right now, perhaps as much as 50-60% of the flow in the river below Reno-Sparks comes from the Sewage Treatment plant. That plant is designed to do a reasonable job of cleaning up the waste water of more than a quarter million people.  Nevertheless, that treated sewage waste water is nowhere near as clean as the water that flows into this valley from the Truckee River and its tributaries.

Official Map from US Weather Service 10-30-2014

So, bring on the storms, please.  One after the other all the way through May 2015.  One can hope.

Related articles across the web

• Tahoe level at 5-year low; no Truckee River flows