Public Meeting: Bridges and Meander Bypasses on Buffalo Bayou

Date is Oct. 17 to Find Out Study Results

And More

Oct. 13, 2019

 

In the wake of disastrous flooding along Buffalo Bayou during and after Harvey in 2017, particularly on upper Buffalo Bayou after the opening of the floodgates on the federal dams, some west Houston residents urged the Harris County Flood Control District to look into whether meanders downstream and bridges across the bayou had blocked the flow, causing them to flood.

In response, using up to $350,000 in public funding from the 2018 Flood Bond election, the District in November of 2018 hired the engineering firm Huitt-Zollars to study the thirty-three bridges and four pipelines that cross the bayou between Highway 6 at Barker Dam and Congress Street some twenty-six miles downstream in downtown Houston.

More controversially, the study also examined the possibility of constructing bypass channels or culverts in thirteen locations, cutting through natural bends in the river. This would be below Beltway 8 where the bayou twists and turns, as rivers naturally do, for good reason. (p. 36) Meandering streams are longer and carry more water. Meanders also help dissipate the force of the stream during floods. Such is the power of the underlying geology that even if altered or straightened, rivers will seek to return to their natural channel, breaking through concrete if necessary. (See Tropical Storm Allison, Tranquility Garage, 2001.)

In the 1960s, environmentally-minded property owners on the bayou, including Terry Hershey and Save Buffalo Bayou’s founding president, Frank Smith, joined forces to stop the Corps of Engineers from stripping, straightening and covering in concrete this winding, wooded stretch of the bayou—as the Corps had done earlier, destroying White Oak and Brays bayous.

The Flood Control District is holding a public meeting to discuss the results of the meanders and bridges study on Thursday, Oct. 17, from 6 to 8 p.m. at the Memorial Drive Presbyterian Church, 11612 Memorial Drive, in Houston 77024.

 

 

Maligning Meanders

In the early morning of Aug. 28, 2017, after the peak of the flooding from Harvey had passed downstream on Buffalo Bayou, the Corps of Engineers made the unprecedented decision to open the floodgates on Barker and Addicks dams in far west Houston. Rising water flowing from the rapidly developing north and west of the city threatened to overwhelm the earthen dams. When the gates were opened, residents living along the six-mile plus channelized stretch of the bayou just below the dams were badly flooded. This stretch of the river had been narrowed and straightened by the Corps in the Fifties, essentially reducing its capacity.

But a popular belief continues that the meanders below Beltway 8 caused the bayou to backup and flood homes upstream adjacent to what is now Terry Hershey Park, hence the push to construct channels to bypass or cut through meanders. (Another popular belief, which also persists, is that the “rich people downstream” did not flood. There was, of course, massive flooding along Buffalo Bayou all the way through downtown Houston during Harvey. But that flooding, fed by the rapid accumulation of rain runoff from the city and suburbs below the dams, occurred before the floodgates were opened.)

In October of 2018 Save Buffalo Bayou published a report in response to this widespread mistaken belief about meanders downstream. The report explained why people flooded upstream and how meanders are beneficial and actually reduce flooding. You can read the full report here.

 

A Relatively Natural Urban Bayou Below Beltway 8 to Buffalo Bayou Park. A History of Failed “Improvement” Projects

As urban rivers go, Buffalo Bayou is, remarkably, a relatively natural river below Beltway 8 to Shepherd Bridge, though many property owners have foolishly razed the trees, landscaped with sidewalks and irrigation, or hardened the bank with  concrete riprap or sheet pile, leading to predictable flooding, erosion, and bank failure problems. (See also River Oaks and Houston country clubs.) Below Shepherd, Buffalo Bayou Park between Memorial Drive and Allen Parkway was stripped, graded, and “realigned” by the Corps of Engineers between 1952 and 1959. (p. 592)

 

Buffalo Bayou Below Shepherd

Allowed to overgrow in the intervening years, since 2010 the banks of the bayou in Buffalo Bayou Park have been repeatedly stripped, graded, “improved” and “repaired” by the Flood Control District, with large trees and native vegetation removed for irrigated landscaping and “channel conveyance,” resulting in further erosion and bank failure (and tree loss).

In 2015 more large trees were removed and the bank bulldozed for installation of two massive City of Houston stormwater outfalls draining Shepherd Drive at the intersection of Allen Parkway. In the last year, a growing sinkhole in that area (in the vicinity of what was once a natural tributary to the bayou) has damaged both of the new 84-inch stormwater pipes and caused the sidewalk to collapse, threatening the parkway. Repairs are costing at least $1.2 million, according to Erin Jones, public information officer for the City of Houston Public Works Department.

This is not the “fault” of the bayou, which does what rivers naturally do. Engineers, well paid with public funds, should have anticipated these issues, which began before Harvey.

Removing trees and vegetation, bulldozing, grading, irrigating, breaking up and compacting the soil destabilizes the bank of a river and destroys its ability to cleanse and absorb water and nourish beneficial plants.

 

 

More Funds to Repair Repairs

Currently, the District is spending $9.7 million in federal funds to repair the constantly eroding banks in the park. Save Buffalo Park has asked the District for information on how it plans to “repair” the banks and urged the District to consider the fact that the straightened bayou will continue to try to restore its meanders, eating away at the banks. So far the District has not responded. But a reliable source reports the planned repair methods include sheet pile walls, which are environmentally damaging and deflect flooding and the erosive force of the water downstream and towards the opposite bank, among other problems. Also they’re ugly.

 

Moving Upstream: Above Buffalo Bayou Park

In the long winding stretch between Shepherd Bridge near the center of the city and Beltway 8 out west, there are five locations where, sometime after the early 1950s, the bayou was channelized or bypass channels constructed around meanders (p. 46):

1. For about 250 feet downstream of the West Beltway 8 bridge
2. Immediately upstream or west of Gessner Drive
3. Around Mott Lane in Piney Point Village
4. Beneath San Felipe Road west of Voss Road
5. Beneath Farther Point Bridge just west of Chimney Rock Road

 

Above Beltway 8

Between Beltway 8 and the dams farther upstream, the bayou was stripped, channelized, and straightened in the 1950s. As mentioned above, this six-mile stretch of the river is now Terry Hershey Park, owned by the Flood Control District. Recently, after years of resistance from park users, neighborhood residents, and environmentalists, the district cut down the trees on the south bank, graded the slopes, and bulldozed shallow detention basins there. In the 1990s the District had done this on the north bank, which is now virtually shadeless, covered with mowed turf grass, which is useless for slowing, absorbing, and cleansing stormwater runoff.

The stated purpose of the three basins on the south bank is to briefly hold stormwater overflowing the bayou (in what would have been, prior to channelization, the bayou’s natural floodplain or even the channel itself). The small amount of temporary stormwater detention created is intended to mitigate increased flow into the bayou from future City of Houston drainage projects. This project, together with initial contracts to remove sediment in four channels flowing into Addicks Reservoir, is costing some $13.3 million in Harris County funds, according to Karen Hastings, communications manager for Flood Control. Lecon Inc. has the $13.3 million contract.

 

 

Dredge And Dredge Again

Addicks and Barker dams were built on the prairie in the late 1940s for flood control. Within the reservoirs, which are normally dry, the streams, including most of Buffalo Bayou, remain relatively natural, flowing freely through the floodgates, which stand open until there is a significant rain downstream. However, as noted in the District’s recent public meetings (see below), there is pressure from the District and other agencies to dredge the streams flowing through the reservoirs, which are large public parks.

Upstream of the reservoirs, where homes also flooded badly during Harvey, the bayou and the streams that ultimately flow into it were stripped and channelized decades ago during development of subdivisions. The Flood Control District recently held meetings about their multi-million dollar project to clear these altered channels of sediment and “restore them to their original design capacity.” Apparently that means a trapezoidal shape (basic ditch design), according to Travis Sellers, senior vice president of IDS Engineering, the company responsible for studying and designing the channel dredging project. (Modern ditch design, however, is a two-stage ditch allowing for native vegetation to slow and cleanse polluted urban or agricultural runoff.)

 

 

Does Dredging Work?

Sellers, in answer to questions during the Oct. 3 public meeting about dredging streams flowing into Addicks Reservoir, insisted that the dredging would only increase the storage capacity of the stream “so that it doesn’t flood neighbors downstream.” Increasing the capacity of the streams would have no impact on the amount of water flowing into the overburdened Addicks Reservoir, Sellers claimed.

Part of a river’s natural function is to transport sediment, especially during storm events. Silt and sand carried by rivers, including Buffalo Bayou and its tributaries, ends up rebuilding banks and replenishing beaches on the coast.

Dredging, deepening and widening streams are controversial practices, largely because they increase flooding and erosion, destabilize streams, damage the ecosystem, and only lead to more maintenance, among other things. When the river channel is too wide, for example, the water slows and sediment falls out. As an alternative, some experts recommend focusing on the source of sediment. In the case of streams in west Houston, Sellers agreed that development and uncontrolled runoff from construction sites was a likely source

Here are links to the Facebook video of the Oct. 3 meeting and to the slide presentation about dredging streams flowing into Addicks Reservoir.

Here are links to the Facebook video of the Oct. 7 meeting about dredging streams flowing into Barker Reservoir and to the slide presentation.

 

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