Dammed If They Do, Dammed If They Don’t

The Conundrum of the Buffalo Bayou Dams

Why so much water for so long in Buffalo Bayou?

May 26, 2016

The water in the normally empty reservoir had dropped only a few feet by the time we stood on the earthen dam looking down at the dark, opaque blue-gray surface. After almost a month, the rippling water below was still some twenty-three feet deep, and extended as far as we could see along the thirteen-mile long dam and far into the thousands of acres of flooded woods.

It had taken only a little more than twenty-four hours for the rains that began on April 18 to fill the vast flood control reservoirs in west Houston with a record amount of water: a total of more than 206,000 acre feet, a massive amount of water. Imagine 206,000 acres covered in a foot of water. Enough to cover more than eight times the acreage of both reservoirs to a depth of one foot. That much water would take an estimated four weeks to drain, according to reports at the time.

But that was only if there was no more rain. There was more rain, and it was taking much longer. The reservoirs, vast wooded parks with recreational facilities and nature paths, are still draining. As of May 24, the combined total of the two reservoirs was still about 90,000 acre-feet, down to a little less than half.

And Buffalo Bayou was still flowing high and fast, higher and faster for longer than ever before. Property owners upstream had flooded and property owners downstream who had hoped for more moderate flows were instead seeing long-standing trees falling into the fast-flowing stream, banks eroding, sediment collecting, debris causing water to back up onto their property.

Why was this happening and is there a way out of it?

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The platform containing the control panel for the gates at Barker Dam. Photo taken May 17, 2016

The platform containing the control panel for the gates at Barker Dam standing in what would normally be an empty reservoir and park. Photo taken May 17, 2016

Public Meeting on Buffalo Bayou Dams

Corps of Engineers to Issue Repair Update Wednesday, March 9

March 7, 2016

Updated March 14, 2016

The US Army Corps of Engineers, Galveston District, is holding a public meeting Wednesday, March 9, 2016, to update the public about progress in repairing the Addicks and Barker dams on South Mayde Creek and Buffalo Bayou in rapidly developing west Houston.

The two earthen dams, completed in the 1940s, were labeled “extremely high risk” in 2009 when engineers noticed seepage around the dams’ gates and ends following a heavy storm. The “extremely high risk” designation did not mean the dams were in danger of failing soon. But the possibility of failure combined with the dams’ location upstream of a major metropolitan area lifted the dams into the urgent category.

As a result, the reservoirs, which are dry reservoirs and contain one of the region’s largest parks and recreation areas, cannot be filled to capacity during storms, which impacts the way water is released from the dams before and after storms: faster and more often. (Correction: The Corps of Engineers says that the structural problems with the dams have had no impact on the capacity limit or release rates. This unnatural flow regime in turn impacts Buffalo Bayou downstream. (South Mayde Creek joins Buffalo Bayou just below the dams.) However, most of the flooding in Buffalo Bayou during heavy storms is caused by surface runoff from buildings, highways, streets, parking lots, and other paved surfaces below the dams, which are closed during rain events.

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Barker Reservoir. Undated photo courtesy of USACE, Galveston District.

Barker Reservoir. Undated photo courtesy of USACE, Galveston District.