2013 TBS Work Project: Gabion Weir Construction
By John R. Meyer
John Donne wrote, “No man is an island.” Though he was referring to the emotional health of humans, this also seems it could refer to desert bighorn sheep. Pockets of their population are described as islands but we know that before they had humans replanting them mountain range by mountain range, sheep commingled with one another. Bolstered by some combination of curiosity, hunger and quest for DNA diversity, they have always traveled from their island homes to seek companionship and new horizons.
This natural tendency has had more resistance over recent decades than in days of old. Despite reintroduction efforts, man made obstacles still abound. Human help has enabled them to reestablish their island-like populations in various Trans-Pecos mountain ranges, but their eventual need for interaction with their brethren still comes into conflict with structures such as roads, fences and domesticated livestock.
Like good chess players, biologists have gradually focused not on the current move as much as the next few moves. It would be difficult to say that there is ever enough water in a desert environment. With the help of the Texas Bighorn Society (TBS) though, water sources are starting to accumulate in strategic locations and will continue to multiply during subsequent work projects. The biologists, accordingly, are starting to integrate additional strategies into their efforts to provide sustenance to the reestablished desert bighorns in their native range.
Last year, the idea of helping ease the effort of sheep moving from one mountain range to another took the form of removal of decades-old fencing at the Lado Ranch. This year, it was a step towards biodiversity through stream restoration.
From a separate starting point, Josiah and Valer Austin began Cuenca Los Ojos (CLO), a foundation focusing its energy on harvesting rainwater to facilitate restoration of the land through biodiversity along the US/Mexican boundary. Along this part of the border, the desert bighorn is part of that biodiversity. Their list of accomplishments is extensive but for this particular weekend, Josiah brought along his penchant for waterway restoration through the slowing down of runoff as it passes through existing waterwaysdry streams, creeks and gullies.
Using rock to hand craft structures to control runoff and manage erosion is a centuries old technique. CLO has embraced the oldest methods and combined them with some newer ones to produce a method that is deceptively sophisticated given its few components (rocks and wire).
The project’s location for implementing these synergistic goals, was itself a vital piece of the puzzle. The Adams Ranch contains significant habitat for sheep but also forms a travel corridor to Mexico as a whole. The fact that CEMEX’s primary conservation area for desert bighorns, El Carmen Project, directly abuts it on the other side of the river made the location an obvious choice.
A free flowing exchange of ideas between Texas Parks and Wildlife Department (TPWD), TBS and CEMEX has been around for years with support traveling freely back and forth across the border with Mexico in the form of people, ideas and labor. This year’s work project would add in CLO and their ideas of rainwater harvesting for additional momentum.
Bonnie McKinney, Wildlife Coordinator for CEMEX’s El Carmen Project in Mexico explains, ”Reintroduction of native bighorns was the top priority for the project. In the ensuing years friendships were developed with the Austin's and I think it was in 2006, not sure of the date, the Austins and CEMEX USA purchased the ECLCC (El Carmen Land and Conservation Company-formerly the Adams Ranch) with the goal of land and wildlife restoration. All of us who have worked with desert bighorns in both Texas and Mexico realized the importance of the trans boundary corridor that links bighorn habitat in both countries. Basically we all had the same goal...of working toward trans boundary bighorn sheep conservation. TBS, CEMEX, Mexico and CEMEX USA and Cuenca los Ojos, TPWD and Wild Sheep Foundation have all been a part of this. We all recognize the link in the chain that the ECLCC is as far as connecting bighorn sheep habitat, and that is basically how this project came about: kicking ideas around, knowing we needed more water in this area, building guzzlers for the future bighorns that will use this vital corridor, and water sources for the ones that are using it now, and the added benefit of water for many small and large mammals and a host of resident as well as migrating birds.”
Like any effort involving separate groups, success lies in finding an appropriate ratio of common ground and unique strengths. The passion for sheep is obviously there. Josiah Austin and CLO’s extensive experience with waterway repair work was complimented by Jack Bauer’s considerable experience from his days performing habitat assessment for TPWD. He was also able to visit several completed CLO gulley erosion control projects in Mexico and Arizona in preparation for the project. Stream restoration courses from hydrologist David Rosgen as well as ample time in the field, rounded out his preparation for the role of site manager for the weekend’s construction.
Typical of TBS operations, the project was laid out in careful increments from start to finish. Crews divided up the first morning and began an assembly line of sorts to construct the gabion baskets out of rolls of wire mesh. Those were transported out to the work site where Billy Pat McKinney was already leveling off the stream bed with a front end loader.
The selection criteria for a building site usually includes a large outcropping of rock on at least one side of the gulley that serves as an anchor point. The baskets are laid carefully from one side of the gulley to the other, like giant bricks in a wall. The baskets are woven together and then filled, by hand, with rocks. The size of the mesh (2”x 4”), the baskets and even the rocks (3”-8”) were all based on careful observation of previously built structures. The final product, a gabion weir, works to help the rainwater do what it was supposed to do all along- nurture the land and plant life, instead of continue to strip it down.
Anyone who has frequented the creosote flats of the Trans- Pecos has gazed upon the disrupted cycle of rainwater/ground interaction. Overgrazing from decades ago removes vital plant life that protected, stabilized and nurtured the topsoil. Plants go, then the topsoil goes. What is left is compacted by rain events that are concentrated but infrequent. Subsequent rains tend to run off, stripping away additional precious topsoil and leaving a hardened crust on top of the ground ready to divert the next rain down the closest available gulley.
The purpose of the newly placed gabion weirs is not to dam up rainwater but rather slow it down enough to allow it time to soak in and leave behind its silty cargo. The cycle is reversed as the forceful, scouring action of the rainwater is tamed. At the same time, a steady buildup of soil begins to provide a launching pad for re-vegetation.
Most of the glory came to those working the baskets but the backbone of the operation’s success was the scattered crew who harvested mother nature’s rocky bounty from its scattered origin on the desert floor. The first crew filled Billy Pat’s bucket then he transported those with the front end loader over to the ground near the baskets. Finally, the second crew filled the baskets being careful to maintain the integrity and shape of the baskets.
After a full day and a few dozen deliveries of rocks, the structure was complete. A ceremonial splash of water and a few celebratory photos later, the crew was ready for a trip back to headquarters to refuel for a repeat production farther up the wash the next day.
A different kind of satisfaction comes from stream restoration. Decades of abuse takes time to repair. Most of the rock crew likely went through a Rolidex of feelings while gathering. The weir would be complete soon enough but the topsoil? That could easily be something never seen by most of the workers. Yet in a land where annual rainfall often comes in single digits, renewal is measured in generations.
For those who know the resiliency of desert life, the work was a well planned move in a bigger chess game.