Restoring the Fall River: Background, Problem, Solution

Click here to donate now:

Or Send Checks To:

Fall River Conservancy

Gift Processing

P.O. Box 395

Fall River Mills 96028

Restoring the Fall River

The Fall River originates from California’s largest network of cold-water springs.  In total, the entire system generates approximately 890 million gallons per day—over one million acre feet annually—of cold, clean water.   For perspective, that’s more than 10 times the city of San Francisco’s total annual water use!  The value of this water to our community—and the environment—is almost immeasurable.  We use the water for agriculture, hydropower, municipal drinking supply, and outdoor recreation. Moreover,  large wild trout thrive in this nutrient rich, spring water.

But over the last 10 years an unwelcome visitor has gradually established roots in the Fall River: Eurasian watermilfoil (EWM), Myriophyllum spicatum L.

EWM threatens our ability to fully capitalize on our most valuable resource: cold, clean, plentiful water.  EWM impedes natural flows, destroys levees, floods crops, degrades wild trout populations, and destroys the natural order of the Fall River ecosystem.  Additionally, PG&E spends tens of thousands of dollars annually trying to keep the problem under control using a mechanical harvester that may actually exacerbate the problem.

Background and Problem

Eurasian watermilfoil (EWM) is an invasive, submerged aquatic plant found throughout most of North America.  Over the last 50 years, it’s become one of the most noxious aquatic weeds in the western United States. First identified in the Fall River in 1999, EWM now infests large portions of the lower river.  Although its origins remain unknown, EWM spreads rapidly when plant fragments get redistributed throughout the river by boat props, mechanical harvesting, and other natural methods.  EWM grows extremely fast, forming thick mats in the river that impede flows and causes major flooding events.  EWM also displaces native aquatic plants that bugs and fish rely on for survival.


The Fall River Partnership—Fall River Conservancy, California Trout, and the Fall River Resource Conservation District—have joined forces to develop a viable strategy for managing EWM. In the summer of 2011, this partnership will carry out a two year pilot project that uses a biological control—the milfoil weevil—to systematically reduce the spread of EWM.

The milfoil weevil, Euhrychiopsis lecontei, is a small aquatic weevil that lives and feeds only on EWM.  Once introduced, milfoil weevils eat away at EWM until populations decline to manageable levels. Milfoil weevils do not negatively affect fish populations, native aquatic vegetation, agricultural crops, or any other sensitive species in the Fall River Valley –including people.  As the weevils gradually destroy EWM, native aquatic plants begin to regenerate, bringing with them the diversity and abundance of macroinvertebrates that the Fall River was once known for.  The final result?  More bugs and more aquatic plants mean more fat wild trout!

Milfoil Weevil
The milfoil weevil

Cost Estimate

The Fall River Partnership mentioned above is working together to raise $125,000 to implement a two year pilot program for managing EWM in the Fall River.  Money raised will go towards hiring a professional contractor, EnviroScience Inc., to propagate the biological control (weevils), distribute the weevils in strategic locations throughout the river, and then monitor the results to ensure that the intended impact occurs.

After two years, we’ll monitor the impact of the program to determine whether additional resources should be invested in the program.  The California Department of Fish and Game, the U.S. Department of Agriculture, and the Regional Water Quality Control Board will provide regulatory oversight and guidance to ensure that all necessary permits and procedures are followed.

We Need Your Help:  Please Make a Donation to Help Manage EWM in the Fall River

The Fall River Valley has a unique culture of farming, ranching, and community. The Fall River Partnership is passionate about working closely with community members, landowners, agricultural operators, ranchers, and other stakeholders to devise workable solutions for achieving a common goal. Although Fall River stakeholders differ significantly in demographics, we share a common interest in the general economic, cultural and ecological well-being of the valley.  EWM threatens this common interest. Please help our community address this problem by making a donation today.

The Fall River Partnership believes in working within the community to constructively solve problems.  We also believe in taking personal responsibility for managing the extraordinary natural resources of the Fall River Valley.

Please visit our website to make a tax deductible donation:

Leave a Reply