Weather Window: Water, water everywhere and#8212; in Lake Tahoe, Donner Lake, the Truckee Riverand#8230;
Special to the Sun
TAHOE/TRUCKEE, Calif. and#8212;-The calendar says it is mid-summer, but other metrics suggest hydrologic conditions more like May. Stream flows from our regional watersheds are still running high, a direct result of the heavy winter and cool, damp spring weather that delayed snowmelt this year.
As of July 19, 2011, the Farad stream flow gauge on the Truckee River near the California-Nevada state line was measuring a robust 1,330 cubic feet per second (CFS). A typical flow for around this time of year is about 620 CFS. The high river flow at Farad means water releases from Lake Tahoe will be delayed until the downstream gauges indicate water running at about 500 feet per second. The Truckee River Operating Agreement defines the complex relationship between how water is released and controlled from Lake Tahoe and other regional reservoirs. The bottom line is that there can be no commercial rafting on the Truckee River between Tahoe City and the River Ranch restaurant until the flow at Farad diminishes and allows for more water to be released through the Tahoe Dam. The good news for rafting companies is the Truckee River flow is dropping quickly, which means they could possibly start operations in late July or August for at least a partial season.
Lake Tahoe’s water surface elevation continues to rise and as July 19 was at 6,228.36 feet. That represents about 88 percent possible storage capacity for Big Blue and the highest level since 2006. This year will also be the first to have carryover storage in Lake Tahoe since 2006, a winter that had even more rain and snow than 2011.
In my column about a month ago, I mentioned the cold spring had delayed butterfly emergence on Donner Pass. Professor Art Shapiro, the renowned world-class entomologist and ecologist with the University of California, Davis, recently e-mailed me to report that as of this week there are 36 species flitting about near the Summit. The season is about three to four weeks behind the and#8220;averageand#8221; (since 1973), but is catching up fast. The previous year with such a late emergence was 1983, one of the biggest winters on record. Shapiro’s research indicates during the summer of 1983, the number of species observed in any one day was 36 (out of more than 100 distinct species that survive near Donner Pass). This year, however, Dr. Shapiro expects to see the species diversity count peak closer to 44 to 45.
Dr. Shapiro shared another tidbit of information about the outbreak of the Pandora Moth (Coloradia pandora) in the Tahoe Basin. The mature larvae of these moths are crawling around as caterpillars right now, looking for soft, crumbly soil in which to burrow in order to produce another generation. The big, fuzzy, gray and rose colored moths have a two-year lifecycle, spending the first winter as young larvae at the bases of trees, and the second year as pupae in the soil. These moths are major defoliators of two- and three-needle pine trees, and seem to reach more abundant numbers after a winter with heavy snow. The Pandora Moth pupae and larvae were a traditional food for the Washoe and Paiute Indians during these occasional and#8220;outbreakand#8221; years.
The ramifications from last winter’s epic snowstorms continue to impact the region in a myriad of ways. So enjoy the summer weather and healthy water conditions that bless our environment this year. Statistically, another drought is always right around the corner.
and#8212; Tahoe weather historian Mark McLaughlin is a nationally published author and professional speaker. His award-winning books are available at local stores or at http://www.thestormking.com. You can reach him at firstname.lastname@example.org
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