The Flood of the Century

SPRING 1997 VOLUME XXVI, NO. I The Flood of the Century - Sierra winter storms are likely • to be remembered more by the -~ bridges and houses they carry ~~ away than by their beauty or the thousands of blessings they bring to the fields and gardens of Nature. -John Muir from his first book, The Mountains of California .(1894) While January's flood brought record-setting water levels to Yosemite, flooding in Yosemite Valley and along the Merced River Canyon is as old as the river itself. The tendency -®Inside of the Merced River to Flood Facts .... ... 2 flood was almost imme diately recognized when Season's Preview ........ 3 James Lamon, the first non-Indian to live Planning Your Visit ... 4 & 5 permanently in Yosemite Yosemite's Future .. .. .. 6 Valley, was driven from his home in 1862 by the Shuttle Bus Map . ... Back Panel rising river. But while floods can wreak havoc with human structures, they are extremely beneficial from an ecological standpoint, serving as a sort of natural house-cleaning which scours and alters stream and river channels, redistributes rock, soil, silt, Yosemite Falls roar wbile the rising Merced River transforms and sand, while enriching wildlife meadows into lakes during January's flood. NPS photo habitat. .Continued on page 1 YOSEMITE FLOOD'97 SPRING 1997 VOLUME XXVI, NO.l The Flood of the Centu river, and the shoulders of many park roads are eroded. These changes are part of the natural cycle of events that created Strange to say, the greatest and continue to shape areas within Yosemite. floods occur in winter, What you won't see is the major when one would suppose "damage" experienced by the park's infrastructure. Many of the human-made all the wild waters systems required to support visitors would be muffled and sustained crippling blows. Electrical supply systems shut down. Water-soaked chained in frost and snow. hillsides slid onto roads and power poles But at rare intervals, were toppled. Sewer lines broke, causing contamination of the water supply. warm rains and warm winds Campgrounds, buildings, and roads close invade the mountains to the river's edge were flooded. Some sections of roads were completely washed and push back the snow line away; in other cases, the surge of flood from 2,000 feet to 8,000, water undermined the roadbed, leaving asphalt hanging in mid-air. Sandbars and or even higher, debris covered roads and paths through and then come out the Valley .. the big floods. In the Flood of 1997, the river reached a depth of over 13 feet at the Happy Isles gaging THE WORK BEGINS -John Muir, station and swelled to over 23 feet by the time it reached Pohono Bridge at the Valley's far Much of the park was closed to the western end. NPS Photo public in January and February as a result The Mouniains of this storm. The NPS is working with of California Continued ~m front cover the assistance of many other federal, WHAT HAPPENED? Cascades-normally a relatively narrow state, and local agencies to assess damages Two and a half days of warm and heavy · stream of water-expand to 350 feet across. to park roads, trails, buildings, grounds, rain brought great change to Yosemite Yosemite Falls was a raging gush, causing and park utility National Park during the first few days of the meandering Yosemite Creek to flow systems. Emergency 1997. In the early morning hours of New over roadways and bridges. repairs, salvage Year's Day, rain was falling at elevations PeaKing in Yosemite Valley at about operations and as high as 9,500 feet. In the high country, 11:00 p.m. on the night of)anuary 2nd, long-term planning rivulets in the snowpack indicate a snow the massive volume of water flowed for park restoration line that eventually climbed to 12,000 down-stream, causing streams and rivers are underway. This feet. The deluge of this storm, along with to overflow their banks and carve new represents the a record-setting snowfall in December hannels. Initially, 900 visitors and 1,200 beginning of a that was melted by this rain, created a park employees were isolated in Yosemite recovery effort that high volume of water rarely seen in the Valley when all three highways into will leave Yosemite rivers and waterfalls of Yosemite. the Valley were closed. After the water better than before Witnesses saw Royal Arches ubsided, downed trees were removed and better for park initial repairs were resources and made to Highway better for visitors. 41 sufficient to allow the evacua THE FLOOD'S tion of visitors and ECOLOGICAL many employees ROLE from Yosemite The Flood of '97 Valley. reflects the Merced River's dominant EVIDENCE OF role in forming the THE AFTERMATH character and Despite the ecology of severity of this Yosemite Valley. natural event, Consequently, A 300-foot section of 14-inch sewer line located beneath Highway 140 visitors to Yosemite accurate surveys was destroyed, severing the Yosemite Valley sewer system from the ni.ay be surprised at and document El Portal waste water treatment plant. The sewer line must be how little of the ation of this event reconstructed. NPS photo flood's evidence are underway. remains. What you Aerial photographs, hydrological may see is that assessments and floodplain data are being riverbanks look collected. This information will aid park freshly_scoured managers in their understanding of the YOSEMITE and widened, dynamics of flooding, the beneficial role debris along high floods play in the ecosystem, and the GUIDE water lines dangles effects of human intervention on the in the trees and channeling of the Merced River in Published by the Yosemite Association, shrubs next to the the Valley. in cooperation with the National Park Service and the Yosemite Concession Services Corporation. Edited by Kristina Rylands A 7.5 mile stretch of Highway 140 sustained severe damage. In several Production by Skip Gaynard Designs places, the road and underlying supporting ground layers are gone. Printed by McClatchy Printing Co. NPSphoto FLOOD FACTS KNOWN LOCATIONS OF MAJOR FLOOD DAMAGE YOSEMITE NATIONAL PARK Areas of known flood damage are marked ~~h · • • with a dot. Hetchy I Did You The Tioga Pass Road is above 6,000 feet in elevation and currently covered with snow. Additional flood damage will likely Know... be discovered after spring snowmelt allows for a more extensive survey of the POST-FLOOD park. PRECAUTIONS Reconstruction of roadways and structures continues throughout As shown on the map below, Yosemite. Do not drive or walk many of the park's visitor through any closed, barricaded, or facilities were inundated by roped-off areas. Motor vehicles must flood water. stay on established roads open to public travel. Obey all posted speed limit and direction of travel signs. Yosemite Valley •!• Extent of January 1997 Flood Pohono Bridge to Happy Isles Saturated soils and the high winds that accompanied the flood have D -o1.11.-y- © weakened and undermined a large 0•-o-. nwiiber of trees in developed areas. While extensive survey and hazard GlaclerPulal SOME FLOOD tree removal is currently underway, 7,2141 .• be aware that conditions under and SPECIFICS around trees are unstable. •!• • At least 1.4 miles of riverbank The banks along the Merced River and 550 acres of meadows and other creekside areas sustained (recently restored at a cost of heavy erosion and undercutting $1 million) were eroded by the due to flooding. Be careful when PRELIMINARY DAMAGE ASSESSMENT TOTALS flooding Merced River in walking along any creek or river bank. Yosemite Valley. Losses in CATEGORY RECOVERY ESTIMATE these areas also include 3.5 ~~~-Roads ..... .miles of resource prote<!1aoa--~~ Swfff currents and wet, slippery ~............ = "=-_: Trails . 4,264,000 fencing and 170 restoration - footing can cause you to fall and be signs that must be replaced. swept over a waterfall Never swim 6,160,000 or wade in streams above waterfalls Utilities ................................. or in swiftly moving water. Buildings ............................... 84,083,000 • Approximately half of Yosemite Valley's 900 •!• Grounds (includes campgrounds) ........... 13,li2,000 Watch your step! Tripping and campsites were flooded. falling are common accidents on Natural Resources ......................... 4,277,000 Hundreds of picnic tables, park walkways and trails, especially Cultural Resources .......................... 709,000 bear-proof food storage in icy or slippery conditions. lockers, waste cans, and fire Lost/Damaged Property .................... 2,830,000 grates were washed down river High Country Estimate* ................... 12,912,000 and destroyed. Paved Emergency Short-Term Incident Response .... 13,402,000 campground roads and sites were destroyed or covered with Total Preliminary Recovery Estimate** ...... 178,053,000 over a foot of silt. WINTER IS * Includes all roads, trails, buildings, utilities, cultural and • Nine road bridges in the Valley natural resource preservation above 6,000 feet - to be NOT OVER suffered damage and will need finalized July 1997. repairs. 33 trail bridges The remaining weeks "'*The estimate includes concession-operated, park-owned throughout the park have been of winter weather hold lodging and housing which was flood damaged and destroyed and much of the the promise of additional should be relocated. rain and snow. The latest park's 800 miles of trails snow surveys indicate suffered erosion. that the water content in the snowpack is at • Over 350 motel and cabin approximately 200% of units at Yosemite Lodge were normal. The potential FLOOD VIDEO Now AVAILABLE for serious spring flooded with several feet of flooding still exists. A seven-minute video featuring impressive footage river water, and over 200 of the Merced River at flood stage is now available concession employee quarters from the Yosemite Association. Produced by the were flooded, displacing 439 .

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