Rush Creek flows above Grant Lake Reservior have been in the single-digits since mid-December. When adjusted for changes in Southern California Edison reservoir storage upstream, unimpaired near-natural runoff can be calculated. These unimpaired flows averaged 5.7 cubic feet per second (cfs) in January 2020—the lowest that I can remember seeing for a monthly average.

A portion of the USGS Mono Craters Quadrangle geologic map, with the Parker Creek stream gauge circled in red at top and the Rush Creek gauge circled in red in the middle. The Parker Creek watershed for its size has proportionally more surface sediment deposits above the gauge, and the gauge is lower in elevation than the Rush Creek gauge. Both gauges reported similar unimpaired flows in January after five months of very low precipitation.

For comparison, flows in Parker Creek—a much smaller creek than Rush Creek—averaged 5 cfs in January. Interestingly, Parker Creek has two glaciers in its watershed and Rush Creek has none, a difference that would tend to affect summer flows more than January flows. (more…)

Wow! With 53.3″ of snowfall, February 2019 was Lee Vining’s snowiest February on record. The Lee Vining record begins in 1989, with the previous record 49.0″ of total snowfall in February 1998.

February 2019 was Lee Vining’s snowiest February on record, and included days when it was possible to ski along the shore of Mono Lake. Photo by Robbie Di Paolo.

Total snowfall for January and February 2019 was the third-largest on record with 78.5″, lagging behind the same time-frame in 2008 with 91.4″ of snow and 1993 with 81.2″ of snow. Snowfall this past February was 313% of average, and the January–February total was 209% of average. The (more…)

The Yosemite Museum has published online over 6,500 images of Yosemite and surrounding areas in its Yosemite Historic Photo Collection. There are also photos of people, cultural artifacts, maps, and documents related to Yosemite.

Mono Lake from Bloody Canyon, August 1931

A large portion of the collection consists of beautiful Paiute and Miwok baskets. The Mono Basin—portions of it were once a part of the original National Park—is featured in many of the photos. Here is a sampling of Mono Basin shots that can be found in this amazing resource: (more…)

Peak snowmelt runoff on Mono Lake’s tributary streams is occurring!

Restoration Field Technician Robbie Di Paolo retrieves a temperature logging device in high flows on Rush Creek. Photo by Andrew Youssef.

Lundy Lake Reservoir is spilling, and the Rush Creek peak flow of 380 cubic feet per second (cfs) below Grant Lake Reservoir is being released over the next five days. So far, snowmelt runoff above the aqueduct has peaked at 272 cfs on Rush Creek, 238 cfs on Lee Vining Creek, 46 cfs on Parker Creek, and 23 cfs on Walker Creek. The flows should begin to subside soon given the rapid melting and limited snowpack. (more…)

Snow surveys conducted around every April 1st coincide with the average date of peak snowpack. This year, the surveys were completed at the end of March and revealed a large increase in snowpack over the previous month—from 50% of average to 76% of average!

Map of snow survey locations compiled by Robbie DiPaolo. The Lee Vining Creek watershed above the DWP diversion dam and the Rush Creek watershed above the SCE powerhouse are outlined in red.

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Water courses down the Saddlebag Lake Reservoir spillway, possibly for the first time ever. Photo by Bartshe Miller.

For the first time since at least as far back as 1983, Saddlebag Lake Reservoir on Lee Vining Creek is spilling. This is a rare event—and possibly a first—for the highest lake you can drive to in California.

Saddlebag Dam, at 10,090′ elevation, was built in 1921 to enlarge an existing alpine lake for hydropower generation purposes. The dam was raised and a spillway was added in 1925. The reservoir is oversized compared to the volume of water produced in its watershed, and given the agreement between Southern California Edison (SCE) and the Los Angeles Department of Water & Power (DWP), which requires it to be very low every spring. It is unclear if it has ever spilled before now. Last week it was inches away from its spillway, at the end of the day on Monday it was very full at 9,400 acre-feet of water, and on Tuesday it spilled! (more…)

Last week the Los Angeles Department of Water & Power (DWP) released its preliminary runoff forecast based on record-breaking March 1st snow surveys: 195% of average runoff for the April 1, 2017 through March 31, 2018 runoff year. This volume of runoff is very similar to 1983, the wettest runoff year on record. Due to the warm storms in January and February, the lower-elevation snowpack below about 9,000 feet above sea level is much lower than in 1983, so we are assuming that record runoff is a high-end scenario. That forecast also assumes median precipitation over the next year.

Based on 1983 as a high end, 1995 as a probable scenario, and 2006 as a lowest possible scenario, we modeled the likely rise in Mono Lake based on those past year inflows and probable reservoir operations this year. The result? A 3.8-foot rise in Mono Lake is likely over the next year. Expected Grant Lake Reservoir operations add about half a foot to our forecast.

A 3.8 foot rise in Mono Lake is likely over the next year. (Click on the graph to enlarge it.) Graph by Greg Reis.

All three scenarios have little or no rise before May and a similar rise in May and June, since snow can only melt so fast, (more…)

After the wettest February since 1986 at some survey sites, Mono Basin snowpack is more than double the March 1st average!

Snow water equivalent (SWE) ranges between 205% and 244% of average at the five snow survey sites in the Mono Basin (called snow courses). Gem Pass, Ellery Lake, and Saddlebag Lake have the highest March SWE on record. At the lowest-elevation snow survey site—Gem Lake at 9,150 feet above sea level—SWE was about 10 inches shy of the 1969 record, but it had reached the 1983 amount. The Tioga Pass snow course was 5 inches shy of the 1983 record. In the map below showing the snow courses, portions of the Lee Vining Creek (top) and Rush Creek (bottom) watersheds are outlined.

At Ellery Lake and Saddlebag Lake, in the Lee Vining Creek headwaters, March 1st SWE was already higher than the record April 1st SWE set in 1983! Map by Robbie DiPaolo.

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February 1 snow surveys conducted over the past week revealed an approximately 200% of average snow water content in the Mono Basin. This puts the April 1 average at just over 120%.

The current outlook for April 1, 2017 peak snowpack at the Mono Basin’s five snow courses based on February 1 snow surveys and historic data. Graph by Greg Reis.

It is still early in the season, but even with a dry February and March, it will be an above-average year, and with an average end to the season it will be a wet year. With a wet February and March, new April 1 records could be set!

At the end of the wettest January in the 29-year record for Lee Vining, how do Mono Basin season totals for precipitation and snowfall compare to other years? The season precipitation total (since October) of approximately 15.84 inches of water is among the wettest years recorded since 1989. It is the second-wettest year to date (1997 was the wettest) that we’ve recorded in 29 years as of the end of January.

Lee Vining monthly precipitation. Graph by Greg Reis.

At Cain Ranch, five miles south of Lee Vining and more representative of the precipitation that falls on Mono Lake itself, the 2017 seasonal total of 9.44″ to date is sixth-wettest in 86 years. For both Cain Ranch and Lee Vining, these totals fall into the wettest 7% of years. (more…)