The Mojave Desert RCD is continuing their invasive plant removal/retreatment program with the focus remaining on retreatments in the Mojave River.  Over the years the Tamarisk Beetle (Diorhabda) has been slowly migrating its way along the Colorado River and has recently been found across the California border and along the Mojave River.  Due to the migration of this little beetle the district decided in the fall of 2019 to not treat the usual places and give the beetle a chance to proliferate.  Retreatment at Camp Cady in Newberry Springs was paused again this year as well to allow the tamarisk beetle to settle and proliferate.


A quick survey in the first part of June 2020 showed hardly any blooms and those that we did find were suffering the effects of the beetle.  The district will follow the progress of the beetle and monitor the various tamarisk spots where they show the most sign.  The Diorhabda doesn’t kill the tamarisk plant but puts it in a suppressed state where it will not produce seed and thereby cannot spread.  The hope is while the tamarisk plants are in this suppressed state native vegetation will rehabilitate the areas along the riverbed, using less water and providing habitat for native endangered wildlife.

The district began control of these invasive plants during 2008 and has currently treated the majority of infested acreage from south of the Mojave Forks Dam to ½ mile east of the Barstow Marine Base.  Parcels of non-consenting landowners and critical erosion areas have been avoided.  To date, a total of 2,310 “weed” acres of a total of 10,000 assessed acres of these invasive species have been removed/controlled.   Retreatments will be on-going to make sure all weeds stay eradicated and any new sprouts are treated before they go to seed.  However, if the tamarisk beetle continues to proliferate within the salt cedar in the Mojave River, the need for chemical treatment may not be as necessary.  The district will be contracting with Tom Dudley, UC Santa Barbara to monitor and report on the tamarisk beetle locations, spread and future. Initial funding for removal efforts was provided by a USDA NRCS earmark of funds to the Mojave Water Agency, the Mojave River Basin Adjudication’s Biological Resources Trust Fund, State Proposition 50, and direct funding from the Mojave Water Agency. 

Benefits of this program are:

1. Implement the Mojave Basin Area Judgment (improve riparian habitats, maintain

    ground/surface water saturation at root zone, increase downstream flows).

2. Reduce evapotranspiration of ground and surface waters (water conservation).

3. Reduce salt deposits in the riverbed (water quality).

4. Reduce wildfire potential.

5. Keep channels open – reduce debris damming and severity of flooding.