In Praise of Open Ditches
More Effective, Cheaper, Easier to Maintain, Better for the Environment than Buried Stormwater Pipes
May 22, 2023
For several years a controversy over open drainage ditches has been swirling around the city of Houston. We’ve been scraping behind the scenes, trying to clear up some of the misunderstanding. But the flow of misinformation hardly slows.
The basic misunderstanding is that roadside drainage ditches — grass-lined, maybe filled with lilies, cattails, frogs, fishes, crawdads — don’t work as well as concrete curbs on the street funneling stormwater through metal drains and into buried concrete pipes.
Nope. Wrong. Except in dense urban areas completely covered in impermeable surface, earthen stormwater ditches work much better than concrete street curbs and buried pipes, according to our expert sources.
An Age-Old Prejudice
It’s an age-old prejudice. People look at earthen ditches and think they are backwards. Too rural, rudimentary, unfinished. Concrete is surely more modern, more advanced! (Other people look at flowering roadside ditches and think: how lovely. They look at a brutal concrete curb and sense that the earth is being smothered.)
Developers discovered this long ago. Private developers are responsible for installing drainage systems in new residential areas, systems which are then turned over to the city for maintenance. Over time developers found that while some people appreciated the natural aesthetic and function of vegetated open ditches, home buyers often viewed ditches with distaste, as noted in a comparative study of The Woodlands. (p. 2) So, despite being more expensive and less effective, developers switched to concrete curbs and buried pipes solely in order to sell more homes. It had nothing to do with function. It was purely aesthetic.
How Much More Effective, More Beneficial? Ten Times More
Open ditches can hold more than ten times as much stormwater as buried pipes, among other important benefits. A typical 3.5-foot-deep roadside ditch 1,000 feet long holds 325,900 gallons of stormwater, according to the City of Houston Department of Public Works. By comparison 1,000 linear feet of 24-inch diameter pipe holds only 23,488 gallons.
Note, however, that the City is not fond of all that pretty greenery inside the ditch, even if it helps filter trash and nasty stuff from the water.
People assume that open ditches foster mosquitoes. But in fact mosquitos are more likely to breed in pipes and in catch basins under storm drains. According to the Environmental Protection Agency, mosquitoes breed in shallow water – less than 3 feet – that has been standing for at least 7 days. The agency actually recommends replacing curbs and gutters with open ditches.
Concrete Increases Flooding
The reason is that open ditches have more co-benefits than storm sewers and culverts, as noted in a recent watershed study by the US Army Corps of Engineers. (p. 14) Ditches help cleanse polluted stormwater runoff, allow the earth to soak up rain, and are cheaper and easier to install and maintain. (p. 22) Curbs and gutters, on the other hand, actually increase flooding by collecting more water faster, eventually overwhelming our built and natural drainage systems (creeks and bayous), according to the National Research Council. (p. 183) And pipes settle and crack and need to be replaced. Ditches don’t.
Note that Houston property owners actually get a modest drainage fee reduction for having an open ditch, which is considered pervious surface, which helps reduce runoff and flooding.
Maintenance. Another Misunderstanding
No, property owners do not have to maintain the ditches in front of their property. Yes, they are responsible for picking trash or other debris out of the ditch that might block the flow of water in front of their house. This is equally true in lower-income neighborhoods and well-to-do neighborhoods, like Hunters Creek Village in west Houston (actually a separate municipality). (p. 263)
But the Ditch Maintenance Section of Houston Public Works is responsible for de-silting and re-grading ditches, as well as flushing culverts under driveways and streets within the city.
And yes, there are wealthy, older neighborhoods all over the city with open ditches: Memorial, Briar Oaks, historic Avondale and Courtland Place in the Montrose area, just to name a few, not to mention in the Heights, Rice Military, as well as in dense, shadeless Gulfton and other parts of southwest Houston; Sunnyside to the southeast, Scenic Woods to the northeast, and much more. Friendswood and the Woodlands, too. Usually it’s a mix of open ditches and buried pipes, perhaps a compromise, perhaps the result of ditches getting (illegally) covered over.
Problems: Dumping, Size, Complaints
The most frequently cited problem with open ditches, particularly in front of empty or sparsely inhabited areas, is illegal dumping of heavy trash and construction debris that blocks the flow during storms. The City of Houston provides facilities for residents to dispose of tires, appliances, heavy trash, tree waste, and more for free, but contractors and commercial businesses are prohibited. Privately operated landfills charge a fee. (See info here.) So likely its cheaper, quicker, and easier for some to just dump stuff where nobody’s looking.
Lost in the Woods
The Wonders of Houston’s Great Memorial Park
May 17, 2023
We’ve been spending some time recently exploring the enchanting bayou woods of Houston’s magnificent Memorial Park. Some of these woods were familiar: the marked trails, for instance, part of the Bayou Wilds, open to both hikers and bikers, on the west side of the park south of Memorial Drive.
But we hadn’t been on the little-known trails in the far west of the park north of Memorial Drive and between Memorial and Woodway since riding horses through there as a teenager. And there are still horse riders through there. And bike-riders.
Oddly, we managed to get lost on the marked trails, the purple, blue, red, yellow, orange, and aqua trails of the Bayou Wilds west of the Picnic Loop on the south side of Memorial Drive. The signage can be confusing and even wrong, confirmed a helmeted, middle-aged man on a mountain bike who was studying the map posted on a trail. In fact, we encountered numerous people puzzling over the posted maps and color-coded posts, which, though they give a helpful coded location in event of a 911 emergency, sometimes seemed to point in two directions at once. Some public woods elsewhere have simple, easy-to-read directional signs with arrows and names and distances.
But it was a lovely walk through the shady, tangled woods, and not just because of the trees. We encountered numerous couples holding hands, people exploring together and having a romantic stroll through wild nature, individuals who nodded and smiled, families with happy young children, all reflecting the wondrous diversity of Houstonians.
But we did get lost, not necessarily a bad thing unless you’re on a time schedule. We ended up far to the east (downstream) of where we planned to be, emerging from the woods near the eastern end of the Picnic Loop. Traipsing across the mushy grass in the middle of the picnic area, we couldn’t help but remark that these were actually wetlands—mowed for some reason. It seemed contradictory, given the amount of money recently spent to create a large wetland prairie pond to the west where the playing fields had been. Seems like letting these wetlands grow in the middle of a large grassy area would be beneficial. And attractive.
Magically Lost Again
On another occasion we got delightfully lost entering the woods on a well-worn footpath, on a whim, having already lost a sense of direction, thinking we were somewhere else. (Okay. Getting old and distracted, too.) Actually it was Easter Sunday, and the Picnic Loop area was jammed with people grilling, playing volleyball, playing music, tossing colored Easter eggs; massive, oversized trucks parked everywhere.
Following an informal footpath into the woods (obviously other nature-loving humans were doing this too, treading exploratory paths all over the park as well), we ended up on the main tributary creek that flows from the center of the park, stepping down and across the sandy banks as we did as a child growing up on the mysterious bayou. Then clambering up the bank and walking back on the lengthy, wonderful, winding Green Trail. The parked car was somewhere.
We hope these magical woods survive the landscaping projects of the park’s Master Plan, though the future seems to be removing a lot of trees (and undergrowth) and taking out the popular picnic area. (p. 78) Some of that may be good. The picnic areas will be disbursed throughout the park. We hope it’s not turning a truly rare wild area in an urban setting into a more managed experience.
Far West Trails
The little-known far west trails seem to be mostly used by mountain bikers, though the enchanting paths north of Memorial are mostly flat and easily walkable. They are accessible from the sidewalk along the northern edge of Memorial Drive. Go to the Living Bridge near the railroad tracks and the Running Center at the western side of the park, take the stairs on the north side of Memorial Drive (or the roadside sidewalk if you don’t do stairs), and walk until you see an empty wooden sign on the right. The path to the right leads into what are known as the Northwest Trails, which are mostly flat, filled with tall Loblolly Pines, wild berries and flowers. The path to the left leads down into the creek bed which takes you through a drainage culvert and then another which leads you into the rugged, hilly trails known as the Triangle between Memorial Drive and Woodway. These trails are also accessible through a large drainage culvert in the Arboretum.
Note that these are some of the large culverts used by wildlife to cross under Memorial and Woodway, as our late founding president Frank Smith repeatedly argued to anyone who would listen.
Late Spring on the Bayou
May 9, 2023
We were a little late for our spring photo of that bend in the bayou. But we had waited for Big Jim, our devoted photographer, to get back to town so he could take the latest in our series documenting the same bend throughout the seasons. We’ve been doing this since the summer of 2014.
It was a beautiful sunny morning, though at first glance the river and woods looked a little dull, sort of empty and flat. Maybe because they were slowly waking up after a long drought, big freeze, and violent storms. The flow in the river was fairly high though, around 1000 cubic feet per second. There had been a thunderstorm earlier in the night.
But Jim’s photos revealed the beauty of the scene. And they brought to mind how very bright green this city spring has seemed. Spring green is indeed a color, a very vivid one. And according to scientists, the reason is that young leaves are still developing their chlorophyll, their green pigment. They’re also thinner.
The wet, sandy path leading in and out of the forbidden woods was still blocked with wire fencing and chopped tree trunks by the Memorial Park Conservancy. But it was obvious that many people were ignoring that. As we made our way out, we encountered another couple in the parking lot getting ready for a walk. They offered advice on the best place to step over the obstacles.