Vegas Verdes: A Coming Attraction on the River Park

Published on September 16, 2020 in the Las Vegas Optic.

The unfolding plans for the revitalized Gallinas River Park, an enterprise led by Hermit’s Peak Watershed Alliance (HPWA) and the Gallinas River Park Collaborative (GRPC), include some very intriguing and creative projects. One that has been in the plotting stage for some time, just recently was awarded a grant to begin con­struction. It is an arboretum with an irrigation system fed by storm water harvested from a nearby parking lot. It is destined for the North end of the River Park near the Highlands Recycling Center and extending South to the ball field and will occupy an integral place in the overall design for the Gallinas River Park.

Selection of featured vegetation in the arboretum and layout for planting is to be determined by local landscape experts. Aaron Kauffman of Southwest Urban-Hydrology has designed the rainwater harvesting and irrigation project and will
over­see its construction. Our Las Vegas arboretum will be an outdoor exhibit of
trees, shrubs, and perennial plants with displays that focus on species that are suit­able for our climate and soils. It will be accessible with pathways and borders, identification labels and an interpretive sign.

And finally, it will provide an opportunity for us to learn about the characteristics to look for when selecting trees and other vegetation, and how to keep them alive, once they are in the ground. Residents with small yards will be interested in smaller trees; others might want to learn about plantings that will provide color. Still, others want to avoid mistakes such as locating a sun-loving shrub in total shade or a delicate perennial in the path of the wind.

There is no decision yet as to exactly which trees and shrubs will be included in the arboretum’s exhibit. Natives will be preferred, however a number of non-natives have adapted well to our part of the world and will not be excluded. Culturally traditional/medicinal species will be among the plants chosen for display. Examples of some trees that may not be familiar to many of us but that love our climate are the golden rain tree and the lace-bark elm. These are not natives, but they thrive here. A small native tree that might be something new to try is the New Mexico privet. For all species that are eventually selected for the arboretum, emphasis will be on drought tolerance and known viability in our area.

No matter the size of your plot, the use of invasive vegetation is an error to be avoided by all. Invasive trees and shrubs are usually non-natives that have been imported for what might have at the time, seemed to be a good reason. Once established, they take over and drive other plantings away. The Siberian Elms that line our streets come to mind, though some arborists have recently reminded us that they do provide shade. And in the hotter months, we need shade. Nevertheless, we might be looking for alternatives and the arboretum will be able to help.

Roughly 15 trees, 30 shrubs, and 60 perennial plants are proposed for the arboretum, and though they are mostly drought tolerant, they yet require water —especially until they become established. The water harvesting aspect of the arboretum project is a truly brilliant plan. The rainwater that now falls on the parking lot at the recycling center runs toward the arboretum site and into a storm water sewer. The new system will capture that valuable water before it gets to the storm drain, redirecting it into a specially designed concrete collection basin at the edge of the parking lot.

From the basin, water will be distributed via a covered perforated pipe (sometimes known as a French Drain) laid along a shallow gravel filled trench. From that, the water will be able to seep into the soil and reach the tree roots. Once the water leaves the collection basin, none of it will be lost to evaporation. No irrigation water will be taken directly from the Gallinas River. In times of drought, a simple solution answers the need.

A proposed tap into the effluent line that runs beneath the site will provide supplemental irrigation. The irrigation structure to be used for the arboretum is a
large system and beyond what most homeowners would need. Nonetheless, it will demonstrate the possibility of capturing and using rainwater from such surface as patio, driveway and roof. It is water that otherwise would slip away down a storm drain. The arboretum and its irrigation system together will showcase possible plantings for all landscapes both large and small, and will reveal a new approach to dry-climate yard watering for homeowners.

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