NOT DEAD YET! Mesquite Bosques in Borrego Valley
Last updated 12/9/2024 at 8:12am
Note: This article summarizes research done so far by researchers at UC Irvine, with Proposition 68 grant monies from the state Department of Water Resources. The project is called the “Groundwater Dependent Ecosystems (GDE) Identification, Assessment, and Monitoring Program.” It’s important to note that this research is ongoing and has not been reviewed by the Watermaster Board.
What is a “Groundwater Dependent Ecosystem” (GDE)? It is an ecological community of species – plants, animals, insects etc. – that depends on groundwater emerging from aquifers or on groundwater occurring near the ground surface. The life surrounding a spring is one example. In our area, the most evident GDEs are the mesquite bosques, generally located east of Borrego Springs, of which it is estimated there are 2800 acres total.
You might have seen a thriving bosque (from a Spanish word meaning “forest”) at the western side of Clark Dry Lake, off Rockhouse Trail. The biggest mesquite bosque is near the Borrego Sink, which is lowest point in the valley and. It is easiest to access from southeast of town just after the County Public Works facility, after Borrego Valley Road has become Rango Way and then Rango and Yaqui Pass Road meet; just turn north there. You’ll see a lot of dead mesquite bushes or trees, but also many that are still alive. Where do they get their water?
Recent research by UCI uses the differing chemical signatures of water that comes from rain vs. from groundwater, and demonstrates that the bosque near the Sink uses from 30 up to 100% groundwater – the higher percentage occurring when it has not rained for months. It is thus a GDE, and under SGMA (the Sustainable Groundwater Management Act) must be treated as a “beneficial user” of water, and considered in managing the Borrego aquifer, which it is in the current Borrego Springs Basin modeling. For further information on SGMA and the Borrego Springs mesquite bosque, stay tuned to the Sun!
If you wish detailed technical information, here is the link to the presentation on this project offered at the UCI Steele-Burnand Desert Research Center last month:
