NORTHWEST TERRITORY: Stream gauges unreliable in flash-flood conditions

LITTLE ROCK — The March and April floods that rate as 25-year to 50-year events have made instant old-timers of everyone living in Northwest Arkansas.

Whenever typical rains fall during the next few years, people will be able to tell newcomers, “You should have been here in the spring of ’08.”

Of the two floods, however, the second was the most memorable.

While the rainfall overnight last Wednesday wasn’t as much as the mid-March deluge, the impact of its runoff was worse. With the rain pouring down as hard as 2 inches an hour over a period of six to eight hours, the result was flash flooding along area rivers and creeks.

“The water is coming up tremendously fast and with a lot of velocity,” canoeing outfitter Brad Wimberley reported last Thursday morning from Turner Bend on the Mulberry River.

By day’s end, the river rose 18 feetto nearly match the 18.3-foot rise of the March flood, about 14 feet coming in four hours or less.

The situation was similar on the Kings River at Trigger Gap, where Ernie Kilman with Kings River Outfitters was anxiously watching the surge.

“The river is coming up before my eyes,” Kilman said Thursday morning. “It has come up about a foot in just the past 20 minutes. It’s incredible.”

Although the rise of 30 feet fell shortof the 35-foot rise in March, its rapidity was especially noticeable in the creeks feeding into the river.

Wayne Williams of Rockhouse, for example, saw water during the March flood back up on his property along Rockhouse Creek to the highest level anyone could remember. Yet, the high fence around his large garden and the cross fences of his pastures survived.

This time, however, the rush of water down the creek flattened all the fences.

“It’s the worst I’ve ever seen it,” Williams said.

By noon Thursday, the White River near Fayetteville crested at more than 24 feet and War Eagle Creek rose to 26 feet, both sending a swift and mighty surge into already-brimming Beaver Lake.

Along with heavy inflow from other tributaries, the lake quickly rose to a record level of more than 1,132 feet, requiring the floodgates at the dam to be raised 3 feet and then to a record 9.5 feet,causing serious flooding downstream.

The height and rapidity of the rises along the region’s rivers and creeks were revealed by strategically placed gauges maintained by the U.S. Geological Survey. Such gauges can be accessed in real time on various Internet Web sites and are monitored by many owners of streamside properties and avid kayakers and canoeists.

However, it’s one thing to see what a gauge is showing on a computer screen and quite another to witness what is happening while standing streamside.

Seeking some perspective of my own, I headed out midmorning Thursday for the West Fork of the White River to view the effects of the flood on a stream I had paddled six days earlier.

During that float trip, the Geological Survey gauge near Fayetteville was reading 6.7 feet, indicating an optimumfloating level for the seven-mile stretch from the Brentwood roadside park on U.S. 71 to Riverside Park in West Fork. Early Thursday morning, the level was at nearly 21 feet and still coming up.

When I arrived at Riverside Park, the river was really ripping and roaring at an amazing level over the park’s spillway dam near the Arkansas 170 bridge. However, clumps and leaves collected on the trees beside the spillwayindicated it had already dropped 6-8 feet.

The crest had actually occurred three or four hours earlier, according to a local resident at the scene who said the rise was the biggest she had seen in 25 years.

The lesson was that the gauge is only a general indicator of when and to what degree a rise is happening miles upstream.

The same can be said for other gauges that serve many miles of waterways in large watersheds, as well as gauges serving as guides for several streams.

The Frog Bayou gauge near Rudy, for example, serves about 18 miles of that stream and also is listed as a paddler’s guide for flows on Clear Creek and Cedar Creek.

The Kings River provides a better example of a gauge serving many miles of stream. The gauge is located on the river near Berryville and is just downstream from the confluence with Osage Creek, which can influence its reading.

For an outfitter like Kilman at Trigger Gap, located 11 miles upstream, the gauge only tells himwhat he has already seen. Worse, it doesn’t tell him what’s coming down the 34 miles of river between Trigger Gap and Marble, or from even farther upstream from the headwaters of the river near Kingston.

He has noted in the past that it can take as much as 12-14 hours for a rise at Marble to reach Trigger Gap.

“On our part of the river, the gauge doesn’t show how much [water] is coming or how fast it’s coming or what we need to do to get ready,” Kilman said.

He remained on vigilant watchthe entire night during last week’s surge.

“We need another gauge on the river at Marble, if for no other reason than safety’s sake,” he added.

He makes a good point. Given the popularity of riverfront property and on-the-water recreation in our growing region, we could probably use more gauges on other streams.

Even so, paddlers should only rely on existing gauges as a guide in the aftermath of big rises, then trust their own eyes from the banks.