The worst fears of flooding last week in Yosemite were unrealized (for now) and the park has reopened.
The Merced River (measured at the Happy Isles Bridge below Vernal Falls) crested at “only” 3000 cubic feet per second at 11 PM on Saturday night. The chart below shows the flow doubling over the course of the week, as well as the hourly fluctuations which show peak flows each day around midnight.
Peak flows of 3000 CFS or greater are not uncommon – flows reach that level in 30% of all years. The highest ever recorded was 9030 CFS in 1997 after the New Year’s deluge.
On June 20, 2017, the flow at Happy Isles reached 4270 CFS – a value that may yet be surpassed this year when the weather warms up.
Last week Sacramento station KCRA posted stunning aerial video of Wapama Falls. Beginning with a close-up of water tumbling over rocks beneath the pedestrian bridges, the video then all too quickly zooms out to show the falls in their entirety – giving a sense of Wapama’s magnitude. (The combination of Wapama’s flow and height are unmatched by any of Yosemite’s outstanding waterfalls.)
Wapama also reached a peak flow of 848 CFS for the week late last night. Unfortunately the footbridges are unsafe to cross at high levels – at least 4 deaths have occurred – SO DO NOT TRY TO CROSS THE BRIDGES WHEN THEY ARE MARKED CLOSED OR WHEN THEY ARE UNDER WATER. The National Park Service has been working on improving the bridges, which they hope to have completed by next year.
The present state of the bridges at Wapama (unsafe at high water) is one more example of how visitor access has been denied to the Hetch Hetchy area of Yosemite National Park. If you have not already done so, please sign our letter to the Superintendent to support improved access at Hetch Hetchy.
