Weather Window | Prosser Reservoir saves the day
TAHOE/TRUCKEE, Calif. andamp;#8212; Recent snowstorms have greatly improved the regionandamp;#8217;s skiing/snowboarding experience, but the dry powdery snow hasn’t done as much to help ameliorate this winterandamp;#8217;s precipitation deficit. Statistically, the months of March and April account for about one quarter of our annual precipitation and nearly 30 percent of our snowfall, so there is still plenty of time to bump up the numbers.When it comes to forecasting stream flow generated by the melting Sierra snowpack, hydrologists rely on snow surveys and automated sensors, but sometimes the packandamp;#8217;s water content doesnandamp;#8217;t tell the whole story. The winter of 1963 was also a slow starter with no meaningful snowpack in January, but an intense rainstorm at the end of January and significant snowfall in March and April boosted a meager season to the 16th wettest since 1946. Not only did the late-arriving rain and snow break a severe three-year drought, but Lake Tahoe rose 3.4 feet that spring. The biggest challenge in 1963 was the mitigation of widespread flood damage in the Truckee River drainage after a powerful Pacific storm inundated the Central Sierra. Mount Rose was doused with more than 13.5 inches of water in 72 hours, setting a new Nevada precipitation record. On the Sierra west slope, the Big Bend Ranger Station measured more than 21.5 inches of rain in three days. (Hydrologists estimate that the frequency of return for such a storm is 88 years.) The torrential rain coupled with snow levels exceeding 8,000 feet generated intense runoff out of the mountains. For the third time in 12 years, the normally peaceful Truckee River turned its fury on Reno. At the Farad gaging station near the state line, the flow reached 12,000 cubic feet per second. The normal controlled flow at that site is between 400 and 500 cfs. Flood debris in the muddy torrent pummeled bridge supports in Reno, and authorities were forced to close 10 of the 12 bridges in the Truckee Meadows. Water on the runway shut down the Reno airport and incoming flights were redirected.All major highways in the Lake Tahoe region were closed due to flooding, rocks and debris. The California Highway Patrol in Truckee closed U.S. Highway 40 over Donner Pass due to nearly 20 washouts. Route 89 along the Truckee River between Tahoe City and Truckee was underwater and Squaw Valley was cut-off when Squaw Creek flooded the road. Even the trains-Sierra routes run by Southern Pacific and Western Pacific railroads were blockaded by rock and mudslides.In the early morning hours of Feb. 1, a volunteer army of men and boys tried to protect Reno by filling sandbags and building barricades. National Guard troops were deployed, and Reno police and fire units were split on both sides of the river in case all the bridges washed out. Despite their best efforts flood waters ultimately inundated the downtown district. Fortunately there were no fatalities or injuries, and overall damage was much less than prior floods of similar magnitude. The Truckee River channel had been dredged after a disastrous flood event in 1955 and the newly completed Prosser Creek Reservoir added another 30,000 acre feet of storage capacity to Boca Reservoirandamp;#8217;s 40,000 acre feet. The Washoe Flood Control Project manager, H. Smith Richards, said, andamp;#8220;Usually we donandamp;#8217;t like to fill a new dam this fast, but in this case there was no choice andamp;#8230; and without a doubt Prosser Dam kept [Reno] flood damage from soaring any higher.andamp;#8221; The 1963 hydrologic event tested the Truckee River flood control system and confirmed the importance of expanded upstream storage. Within seven years Stampede Reservoir would be completed, adding another weapon in the battle to tame the Truckee River. andamp;#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 email@example.com
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