Numerous studies, including those by the National Park Service and the University of Wisconsin have confirmed that Hetch Hetchy Valley can be readily restored. The only questions are how much human intervention is desireable and to what degree should we let nature take its course.
Removing some dams can be difficult, because sediment can build up behind them. This will not be a problem at Hetch Hetchy – there is little sediment behind the dam due to the granite rock of the Tuolumne watershed.
The Tuolumne River would immediately return to its natural course. Grasses and sedges would return on their own within a few years, and wildlife would follow.
As the reservoir is drained and the valley floor is exposed, replanting of native plants could take place as soon as the soil dries sufficiently. Revegetation could include the planting of a mixture of native trees and shrubs: black oaks, black cottonwood, white alder, Douglas fir, dogwood, willow, azalea, manzanita, and ceanothus to name a few. These species of trees and shrubs will be planted in areas where they originally existed, along with an understory of herbaceous plants.
Non-native plants such as Mediterranean annual grasses could be expected to invade the emerging valley in its first few years, and should be suppressed. The “bathtub ring” from the reservoir will fade naturally and surprisingly quickly, as lichen colonies return. Prescribed burning will be used to prevent conifer encroachment in oak woodlands and meadows, and maintain the fire ecology of the valley as it was before European immigrants arrived.
People from around the world will want to see the dam being dismantled and the famous valley recovering. Engineers, ecologists, environmental restoration experts, native plant and fish specialists, and other scientists will want to study and learn from any and all restoration projects. School groups and the public will be able to observe the process, and some of the cost of restoration could be covered by guided tours for fee-paying visitors.
What will the restored valley look like? Will it be wilderness? Will it be swamped with cars and visitors just like Yosemite?
A restored Hetch Hetchy almost certainly won’t look like Yosemite Valley. Yosemite was developed according to 19th and 20th century conceptions of public access to wilderness. Today, no-one wants to see lines of cars or hotels spread along a monumental valley within a National Park.
We have the opportunity to create an experience of visiting Hetch Hetchy Valley that could be, at least in many respects, superior to present-day Yosemite Valley. We will need a management plan that protects its wilderness character while maximizing opportunities for access to visitors with any sense of adventure – one that visitors throughout California, across America, and around the world can be proud of.
Responsibility for the design of recreational access to the restored Hetch Hetchy Valley will ultimately be up to the National Park Service, working with public input to implement current best ideals for sustainable, low-impact use.
Shuttle buses or a tramway might provide access to the Valley: other National Parks such as Zion already use one or both of these methods). This no-charge public transport will lead from the park entrance station to the edge of the valley, bringing in visitors and the gear they need to have fun - bicycles, kayaks, fishing rods, ice chests, backpacks, camping gear, etc.
Paths and walk ways would be created; some would provide easy access to the river and points along the valley floor for those wishing to day-hike or for families. Other trails will lead to more remote campsites in the higher reaches of the valley and connect to the existing trail system in the rest of Yosemite National Park.
We’d like to see an unobtrusive visitor center, providing information and education on the history and ecology of the valley. We would also highly recommend a cultural contact area where the story of Native Americans who lived in the valley would be told.
You will be able to enjoy nine more miles of the Tuolumne River, now connecting the designated Wild and Scenic River below Hetch Hetchy Valley with the Grand Canyon of the Tuolumne and its headwaters in Tuolumne Meadows. There would be access to side canyons, such as Rancheria Falls, and perhaps a trail ascending Kolana Rock.
Most of all, you will be able to stand, as John Muir once did, waist-deep in grass and flowers, as you marvel at the valley's towering cliffs and thundering waterfalls. Hetch Hetchy will once again be an iconic valley in Yosemite National Park, and an attractive alternative to its often overcrowded sister valley 15 miles to the south.