FLOOD OF 1997 & FLOOD RECOVERY

The Flood of 1997

Heavy rain. Warm temperatures. Heavy snowpack. On January 1-3, 1997, these three elements combined to create the greatest flooding in Yosemite since gauging stations were first installed on the Merced River over 80 years ago. Flooding in Yosemite Valley and the Merced Canyon is as old as the river itself. Water rushed into the Valley and then slowed and spread out, dropping sediment and sand. Standing water was 6-10 feet in places. While flooding is a natural process that is ecologically beneficial, floods can wreak havoc with structures and facilities.

To the human-created infrastructure, the January 1997 flood was "the most devastating flood." The Valley was closed from January 1 to March 14, 1997. The El Portal Road (Highway 140) was severely damaged and remained closed until Memorial Day weekend. The Valley lost approximately half of its campsites (about 350), 200 concession employee housing units, over 50% of accommodations at the Yosemite Lodge, and 33 backcountry bridges. Luckily, no human lives were lost.

Damage of Yosemite's Flood

Damage totaling over $178 million was assessed following January's flood. This included:

Roads and Trails: A 7.5-mile stretch of the steep and narrow El Portal Road (Highway 140) was severely damaged in at least 19 locations, including complete washout in several places. An 800-foot section of the Foresta Road in El Portal which serves the maintenance/warehouse complex and a 600-person residential area were washed away. Other roads, road bridges, and backcountry trails and bridges suffered damage.

Utilities: A portion of the sewer line located beneath the El Portal Road was damaged, severing the Yosemite Valley sewer system from the wastewater treatment plant in El Portal. Electrical and mechanical equipment in the Yosemite Creek sewage lift station was severely damaged or destroyed. All three of the Valley's water wells were damaged or destroyed. Support legs for a 69,000-volt electrical tower feeding Yosemite Valley were severely damaged and required complete tower replacement.

Buildings: Almost 300 guest lodging units at Yosemite Lodge were inundated five to eight feet above the floor. 439 concession employee bedspaces and 15 support structures flooded up to eight feet. 250 units at Housekeeping Camp flooded, leaving extensive sand and debris deposits. The historic Yosemite Valley Chapel, NPS Resource Management offices and storage buildings, and an NPS residence were also badly flooded.

Campgrounds: Approximately half of Yosemite Valley's 900 campsites, along with associated roads and restrooms, were flooded and either severely eroded or covered with silt and debris. Picnic tables, bear-proof food lockers and waste containers were washed away.

Natural and Cultural Resources: While flooding is a natural process which does not "damage" natural resources such as meadows, riverbanks and trees, ongoing restoration projects were affected. Cultural resources, such as archeological sites and historic structures, were damaged.

The Significance of the Flood in Yosemite

The flood served to confirm the wisdom of Yosemite's General Management Plan and to guide final planning of the Yosemite Valley Plan. Both documents call for the removal of structures and facilities from the floodplain. Relocating development away from the river will allow natural processes, such as floods, to work unimpeded by structures. The severity of damage and the loss of visitor facilities and park infrastructure prompted Congress to approve supplemental funding sufficient to repair all flood damage listed in the Park's assessment.

Campgrounds Affected by the Flood of 1997

The flooding that occurred in January of 1997 scoured previously impacted river banks and some campgrounds and covered others with rock, silt and debris. Restroom facilities were left with several inches of mud once waters receded. Sewer systems and utilities were severely damaged or destroyed.

Campgrounds within Yosemite Valley were affected to varying degrees depending on their location within the floodplain. Lower and Upper River Campgrounds and a portion of Lower Pines Campground were most affected. These campgrounds are in the main flood channel of the Merced River, subject to frequent, swift-water flooding and are considered to be in the high-hazard floodplain.

Closing of Campsites After the Flood of 1997

Repairing the Valley campgrounds after the flood would have required major restoration work and extensive funding. Instead, the National Park Service decided to wait until the Draft Yosemite Valley Plan was finalized and decisions about campgrounds had been made with public input. Closure of Lower and Upper River Campgrounds, Yosemite Valley Group Campground and a portion of Lower Pines Campgrounds temporarily reduced the number of campsites in the Valley. The park is planning alternative sites for campgrounds and other facilities currently located in the high-hazard floodplain. The total number of campsites will be increased to 504.