When you install WPML and add languages, you will find the flags here to change site language.

1983 Memorial Day Flash Flood, Part I

050913-SierraStories

It’s been 30 years since the big winter of 1983 triggered a massive landslide on Slide Mountain near Carson City, a cataclysmic event that transported thousands of tons of rock and other debris down Ophir Creek. The rock tumbled into Price Lakes and sent a flash flood into the small community below that destroyed several homes and killed one man.

Monday, May 30, 1983, dawned bright and beautiful, capping a weather-perfect Memorial Day weekend, warm and dry. After the long and stormy winter of 1982-83, which was heavily influenced by the most powerful El Ni­ño in the 20th century, residents of the Truckee-Tahoe region were enjoying an early season heat wave. Sun-starved residents basked in summer-like temperatures near 80 degrees at Lake Tahoe. In Carson City, Nevada, daily highs registered 88 degrees or warmer for nearly a week.

With the weather sunny and hot for days on end, a disastrous flood was the last thing on anyone’s mind during this popular holiday weekend, the first of the long-awaited summer season. The snowy winter and a cold, wet spring had left a snowpack 200 percent of average in the mountains, and despite the recent heat wave, there was still plenty of back-country skiing to enjoy. Taking advantage of the conditions, Ronald Mentgen decided to go cross-country skiing in the upper part of the Ophir Creek Basin on the morning of May 30.

Ophir Creek is a small, elongated drainage of about 4.5 square miles that drains down the steep slopes of the Carson Range. The stream traverses the flank of Mount Rose and then follows a drainage on Slide Mountain, where it is anchored by Upper and Lower Price Lakes. These two small ponds straddle the creek within one-tenth of a mile of each other. Eventually, Ophir Creek empties into Washoe Lake, which itself is ultimately a tributary to the Truckee River.

Mentgen started from the Mount Rose Highway and skied across Tahoe Meadows south of the road until he reached the crest of a ridge overlooking Upper Price Lake. After observing that the northern half of the lake was still ice-covered, Mentgen sat down to eat lunch. It was about 11:30 a.m. Moments later he heard what sounded like rushing wind, and “glancing toward Slide Mountain, he observed trees moving downslope in an upright position.”

Meanwhile, high overhead, hang glider Douglas Cook clearly saw what was happening. Cook had launched from the Slide Mountain Ski Resort parking lot shortly after 11 a.m. and taken advantage of the vigorous thermal air currents above Upper Price Lake. Positioned at an altitude of about 9,700’, Cook is the only known eyewitness to the landslides’ impact on the alpine reservoir.

As he soared 2,000’ to 2,500’ above the lake, Cook recalled, “I heard a roaring sound, kind of like the sound of a jet engine really close. I thought I was going to get hit. Out of the corner of my eye I could see a bunch of rising dust.” The seasoned glider pilot, with more than 1,000 successful launches, watched a big chunk of Slide Mountain collapse into Upper Price Lake. “When it hit the lake,” he said, “it was like a huge explosion. It just blew the lake apart. It looked like a tidal wave at first and then the canyon gathered it up.”

At that moment, Cook was the only person who knew that a landslide containing 1.4 million cubic yards of rock material had just plummeted into Upper Price Lake. The force of the slide displaced 20 acre-feet of water and slush from the lake, and unleashed a torrent of mud, rock and debris into the canyon below. Concerned about people fishing, hiking or living downstream, Cook traced the Ophir Creek channel from his vantage point high in the sky as the ominous snake’s head of destruction surged toward civilization. Anyone caught in the path of this violent flash flood was doomed. “It didn’t have a chance to dissipate before it got down there,” Cook noted. “I saw trees just getting plowed down and it was gaining momentum. At this time, it was between 40 and 50 feet high, weaving down the canyon.”

He began to race with the flood surge to warn downstream victims, but soon realized the futility of his attempt, so Cook flew back to the Slide Mountain launch area. From the ski resort parking lot, Cook and his friends looked down as a “big, brown wave crossed Bower’s Mansion road (Old Highway 395) and saw a school bus and cars being washed out.”

Similar to a powder avalanche, the incredibly fast-moving slurry of rock and mud seemed to have a “super-elevated surface” as it surged down the channel. When the debris collided with large conifer trees, the impact snapped the mature pines like twigs. Catastrophic floods caused by reservoir spillage are not an everyday occurrence, but neither are they unusual. In contrast, the forceful and nearly instantaneous expulsion of a reservoir’s contents, as occurred at Upper Price Lake during this event, is a rare event.

It was lunchtime on that hot Memorial Day, and Tom Reed, his wife Linda, and three companions, Joseph Valenzuela, Tim Miller and John Burruel, were finishing off the interior of Reed’s newly built home on the north-bank of Ophir Creek. Located less than a quarter of a mile downstream from the mouth of the canyon, the house sat just outside of the estimated 100-year flood plain. Tom Reed noticed the creek was running faster than normal due to rapid melt from the snowpack, but it did not concern him. Suddenly, Burruel heard a roaring noise. “I heard the creek make a rumbling sound and I asked Tom if it always did that,” he said. “Then, Tom and I both looked out the back window and we saw a mountain of dirt and trees coming out of the ground like someone was tearing things up with a bulldozer.”

At that point, anyone trying to flee the leading edge of flow was running from a wall of boulders, cobbles, gravel and debris towering 20- to 30-feet high and 100 feet wide. Instinctively, all five started running in a desperate race for their lives.

Stay tuned for part 2 in the next issue.

This dramatic account of the 1983 hydrogeological event at Ophir Creek is based on research by Patrick A. Glancy, U.S. Geological Survey, and John W. Bell, Nevada Bureau of Mines and Geology.

0