Vegas Verdes: The Next Stage

Published on August 19, 2020 in the Las Vegas Optic.

After much time and effort, the hard work of funds procurement has once again paid off and money is in hand to begin Phase II of Rewinding the Gallinas. The New Mexico Environment Department has awarded Hermit’s Peak Watersheds Alliance (HPWA) $485,000 from the River Stewardship Program. The final design for the project is complete and the contracts have been awarded. Let the work begin!

The grand plan of the Gallinas River Park Collaborative (GRPC) together with HPWA envisions a revitalized and rebuilt river park with a restored and healthy river at its heart. Last fall in this space, we described with great enthusiasm the already completed Phase I of Rewinding the Gallinas covering the one-third mile downstream from Bridge Street to the second foot bridge. That project saw the planting of many species of riparian vegetation and the replacement or addition of meanders, riffles and pools in the river that had long ago disappeared. It also added storm water runoff treatment in the form of rain gardens constructed in the West Las Vegas High School parking lot, as well as three other storm water treatment structures closer to the river. If one were fanciful, one would notice the river perk up and smile.

Work is now set to begin on the quarter-mile from the second foot bridge downstream to Independence/Prince Street. This section of river will cost more to revive than did Phase I because there are some unique problems to be addressed. The footbridge footings are too close to the river. Ideally, they would have been placed several yards away from the river bank on each side. Their position interferes with the water flow and river bank and bed erosion has resulted. The restoration plan calls for strategically placing and anchoring boulders in the area around the bridge, in and near the river to stabilize the river banks and prevent further erosion.

At three sites, two on the west side and one on the eat side, culverts direct dirty, contaminated, trash-filled rainwater runoff directly into the river. An elegant solution to this problem is to install storm water infiltration basins. These basins, each 10 to 15 feet in diameter, stop the flow and direct the water downward into the soil which filters out contaminates and other impurities. Water from one of the culverts on the west side will flow into a single infiltration basin.

In times of high flow, the excess will continue along a flood-plain swale that is filled with plants and where more downward seepage takes place and finally, any remaining water arrives at a wetland pothole – which to our untrained eyes, looks like a tiny pond with cattails and other water plants. The second site on the west side is where the Arroyo Pajarito now drains through a dilapidated culvert and empties directly into the river.

The culvert will be removed and a series of step pools (infiltration basins situated in a descending line) will receive runoff from the arroyo. On the east side, the water from the culvert will be redirected into another series of step pools and from there into a quite large pond that will further remove contaminates. The pond was originally built in the 1980’s and attracted ducks and other aquatic birds. Because of regularly dropped sediment, the pond is today a shallow wetland, entirely hidden by cattails and with no open water – thus fewer birds. The project will restore open and deep water to the pond thereby enabling it to maintain diverse plant life. It will once again attract water loving fowl – making birders happy. Furthermore, the pond will collect and store significant amounts of carbon, doing its part to reduce greenhouse gases.

Phase II also carries on where Phase I completed its work. Its plan call for the restoration of natural structural features of the river that have, over decades, been lost. Meanders, riffles and runs will be constructed, and pools scooped out in the meander bends. Judiciously located boulders will be installed and anchored. Beyond the river channel, more riparian vegetation of great diversity is to be planted and attention will be given to the maintenance of wetland areas to insure a mix of open water and marshland. Thus the restored Gallinas will allow trout to thrive and will slow and deflect the stream’s energy and reduce erosion. The riparian environment will provide habitat for the critters that feed the fish as well as for other wildlife, and shade to cool the river. Wetlands are home to still more plant life, and will help mitigate flooding and providing storage for excess water. The River’s valley, through which the Las Vegas stretch flows, is narrow and so the river and its environs must accommodate.

I hope readers remember the flood of 2013 – the small parking lot on the east side of the river on Bridge Street was under several inches of water. With the work now underway, the river will have a greater ability to keep much of the water we saw in that flood within its banks or in the soil. If you have questions or comments about what’s happening along the River, or if you would like to view the design plan, you may e-mail Lea Knutson at lknutson@hermitspeakwatersheds.org.

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