Rain-swollen Merced River begins to recede in Yosemite Valley after rising to flood level

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

The Merced, which normally ambles its way through the valley, swamped meadows and swallowed picnic tables Sunday.

Yosemite Valley reached flood stage about 9 p.m., when the Merced rose above 10 feet, park spokeswoman Jamie Richards said. According to the National Oceanic and Atmospheric Association, the river peaked at 12.7 feet at 4 a.m. Monday and has started to recede.

Richards said Monday morning that roads are open in the valley but work crews were assessing rock slides along Highway 120 and 140 inside the park.

At Sentinel Bridge, the current moved faster than it had Saturday, carrying large tree branches and smaller debris. The arched opening under the bridge was reduced to a sliver of space between the river and the rock overpass.

About 10 a.m., a measurement marker on the side of the bridge showed the river was at nearly 10 feet.

Crows cawed overhead and scavenged for food around the marshy meadow.

The paved walkway leading to views of Yosemite falls from Cook’s Meadow was flooded.

The river lapped against a low pedestrian bridge. A plastic water bottle and bits of garbage floated in the water, presumably carried by the current.

Clouds hung just above Lower Yosemite Falls, dividing the landscape’s color scheme: gray granite and condensation; red and green fall trees; and yellow river-flattened grasses.

The river surpassed its bank, coming right up to the wooden fence that prevents visitors from damaging native plants.

The National Weather Service had predicted Saturday the river would crest at 17 feet 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 cresting river still was 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 was expected to recede to near 7 feet by Monday afternoon.

Housekeeping Camp, which is used only in the summer, had snow, slippery ice and a new stream flowing through it. Some parts were flooded, with water coming right up to the housing structures.

Many of the cabins sit slightly elevated but some were flooded with several inches of water. A large dumpster sat at the center of one particularly large pool.

Half Dome Village (formerly Curry Village) looked largely unscathed by mid-morning. Some tent cabin areas were flooded but the cabins themselves are elevated. Drainage flowed down the face of Glacier Point in the background.

Two Aramark employees cleared mud, logs and sticks off the roads leading into and around the village.

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.

Had the river crested at 20 feet, 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.

The lower crest is expected to result in far less damage. 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 9, 2017 at 5:30 AM with the headline "Rain-swollen Merced River begins to recede in Yosemite Valley after rising to flood level."