Yosemite Valley gets a brief reprieve, but flood crest expected Sunday night

Yosemite Valley got a reprieve from rain for a few hours Sunday, but not from rising waters as the Merced River continued to swell from Sierra storm runoff.

The Merced, which normally ambles its way through the valley, was swamping meadows and swallowing picnic tables Sunday morning. The National Weather Service had predicted Saturday that the river would crest at 17 feet – well above flood stage – by Sunday afternoon.

But the storm confounded forecasters as the brunt of it slipped northward for a time. The Merced at Pohono Bridge, near the mouth of the valley, was at 9.2 feet at 2 p.m. Rainfall had stopped for a time Sunday morning, but by 3:30 p.m., a steady rain was pelting the valley again.

The National Weather Service said the river was expected to crest at 12 feet Sunday night – deep enough to flood some campsites at Lower Pines and North Pines campgrounds, and a sewage pumping station, but well below the 1997 flood crest of 23 feet. The river will recede to near 7 feet by Monday afternoon.

Due to the flooding threat, Yosemite Valley was closed to tourists and largely evacuated, save for some workers checking conditions around the park, and news reporters. Nonessential employees were evacuated by Saturday afternoon.

Park officials said they believed improvements made in the wake of the 1997 flood – roads were raised, culverts cleaned and key buildings raised and relocated – would spare Yosemite Valley from some of the worst of the damage from 1997.

If the river crested at 20 feet, Yosemite National Park spokeswoman Jamie Richards said, there would have been significant damage to roads and buildings. At that level, the parking lot near Sentinel Bridge would have been under water, the park chapel would have been inaccessible and the Upper and Lower Pines campgrounds would have been flooded.

Instead, officials expected the river to crest closer to 12 feet, which would result in far less damage. At that level, the Swinging Bridge and other bridges could be under water, as well as some meadows. Cleanup would take much less time and would involve clearing roads of any rocks and downed trees and inspecting picnic areas for damage.

Richards said she won’t know when the valley could reopen until officials assess the damage after the storm passes. On Sunday, about 80 personnel remained in the valley, she said.

Thunderstorms were heard throughout Saturday night and into early Sunday morning. At 7 a.m., there were steady, light rain showers. Some walkways near Yosemite Valley Lodge were flooded. Waterfalls spilling into the valley appeared swollen.

On a drive through the empty valley, a meadow along Southside Drive looked more like a marsh, with just the tips of the tall grasses sticking out. Richards said it’s likely all meadows are flooded because they are close to the riverbed. A sandbar next to the other side of the road diverted the flow of water.

Down the road, the rising river had nearly swallowed up a picnic table and benches. Just the tabletop remained above the water line.

Rain started coming down harder at Valley View, which overlooks Bridalveil Fall and El Capitan. A sign several feet from the river illustrated where the water reached at 11 p.m. Jan. 2, 1997.

That’s the last time the valley was evacuated to this extent, Richards said, though there are periodic closures throughout the year depending on road conditions, fires and rock falls.

At a weather monitoring station before 9 a.m. near the Pohono Bridge, the westernmost point of the valley, the brown river surged past markers indicating the water was at 7.5 feet.

It rained steadily, with downpours every so often through the day. Many places had packed snow and ice, due to the storm earlier in the week. The valley was silent but for the occasional ranger SUV driving by.

By 10:30 a.m., the storm had shifted north. Richards said the valley likely would not see the level of flooding that park officials had originally expected.

“We prepared for the worst and hoped for the best,” she said.

By late Sunday afternoon, near the start of the Lower Yosemite Falls trail and a short walk from Yosemite Valley Lodge, a cascade of water from higher elevation flowed over the side of a hill. The water made its way down the paved path and over another small hill, making an improvised waterfall before continuing along the roadside.

As the the river neared its expected crest, more puddles formed or expanded on the roads and meadow flooding expanded significantly, engulfing the roots of trees.

On Southside Drive, muddy water formed a deep pool extending all the way across the road. Water rolled off the the boulders above, making a whooshing sound as it cascades down to the roadside and added to the flooded Meadow below.

Suddenly, a few cracks rang out from above.

“OK we need to get out of here,” Richards said. “That’s the sound of boulders coming down the hill. Let’s go!”

Back at the Swinging Bridge around 4:45 p.m., the water had risen to about 9.5 feet and was nearly touching the bottom of the bridge. The river extended past its bank onto what had earlier in the day been ice-covered grass.

Toward dusk, a gray fog settled over the deserted valley floor, creating an eerie landscape.

“It’s a special thing,” Richards said. “Not many people will be able to see this in their lives.”

This story was originally published January 8, 2017 at 8:29 AM with the headline "Yosemite Valley gets a brief reprieve, but flood crest expected Sunday night."