A light rain began falling in the Yosemite Valley on the morning of December 9, 1937. By the afternoon the light showers had turned into a torrential downpour. Over the next two days the storm continued, drenching the Valley with over eleven inches of rain, wreaking havoc across the Valley
An initial survey of the damage included the loss of the Cascade Bridge, several miles of damaged roads, re-channeling of the river alongside the power house, extensive damage to the power lines that crisscrossed the Valley floor, the complete lost of the intake dam along the South Fork of the Merced River, loss of the Illilouette dam and its intake, submersion of nine sewage pumps stations, severe damage to the Arch Rock Checking Station buildings, damage to seven Valley residences, and the complete loss of twelve CCC buildings. Other damage included the loss of seventeen footbridges, including the Lower Yosemite Falls Footbridge, Tenaya Creek Bridge, three Lost Arrow Trail bridges, and the obliteration of most of the campgrounds scattered about the Valley.
The largest flood to inundate the Yosemite Valley in the park’s history, superintendent John Merriam hoped to use the disaster as an opportunity to remake the Valley. As superintendent, Merriam sought to check the continued commercial development within Yosemite, which often had put him at odds with YP&CC president Donald Tressider.
Park policy had long been to “rehabilitate” Yosemite’s infrastructure after a flood, believing that by repairing the park’s roads, trails, and various other structures, they could not only improve the strength of the facilities but could do so without having to relocate them away from the Merced River.
The 1937 flood demonstrated the limitations of this policy. As noted in the above memorandum to National Park Service Director Horace Albright the estimated cost of the damage was $271, 750, of which the park had only received $50,000 in 1938. “We trust that every effort will be made to secure these funds,” wrote Merriam, “so that the public may realize the greatest possible values from Yosemite this coming summer and during the following park seasons.”
Despite the recession of 1937, Albright was able to provide further funding for Yosemite’s reconstruction efforts, pleasing both Merriam and Tressider in allowing the park to rebuild many of the more popular campgrounds, roadways, and needed infrastructure. Furthermore, labor provided by the Civilian Conservation Corps aided in the renovation, notably in razing the Old Village much to the dismay of many who argued that the buildings were the last physical evidence of the Valley’s pioneer era and so, they should be preserved.
But the true lesson from the 1937 flood would not be understood for another six decades when, in 1997, another massive flood drowned Yosemite Valley. Despite three larger floods, in 1950, 1955, and 1964, development had only spread on the valley floor. Causing $178 million in damages, the 1997 flood forced the park to reconcile the need for visitor amenities with the reality of the Valley’s periodic flooding in the Yosemite Valley Plan of 2000. Under the plan, the park permanently removed three campgrounds and reduced the size of a fourth and called for further restrictions to the number of visitors driving and parking within the Valley. Highly controversial, the plan embroiled Yosemite in numerous lawsuits by a multitude of groups and individuals who believed that it either went too far or not far enough. Furthermore, administrative struggles in resource management further added to the political mess that has become Yosemite planning.
Yosemite’s response to both the 1937 and 1997 floods underlines the inherent problem of mitigating natural disasters impacts on manmade infrastructure, and continued struggles over how much development should be allowed within Yosemite Valley.