The Cost of Invasive Plants in California


Invasive plants cost California at least $82 million each year.

Estimated Annual Cost of Invasive Plant Work in CA
Flyer on costs of invasive plants
in California (download)

This figure represents the state’s current expenditures on control, monitoring, and outreach. Totaling expenditures provides a conservative estimate of actual ecosystem impacts, which are harder to quantify but are estimated in the billions nationally. Management programs are able to address only a portion of the many invasive plant challenges in the state, and funding invested in these programs is expected to repay itself many times over.

A number of authors have tried to put a dollar value on the damage caused by invasive species. Cornell University researchers estimated that invasive species cause $120 billion in damage in the United States each year (Pimentel et al., Ecological Economics, 2005). In Nevada, invasive plants cause between $6 million and $12 million per year in reduction of wildlife-related recreation (Eiswerth et al., Weed Science, 2005).

How we measured economic impacts

Many of the impacts of invasive species do not lend themselves to easy cost estimates. After all, how much is an endangered plant worth? Calculations on the cost of invasive plants sometimes use substitutes such as the damage caused by floods on a river infested with giant reed or the reduced agricultural yield in a pasture covered by leafy spurge.

In 2008, Cal-IPC and Sustainable Conservation surveyed agencies and organizations to gather a rough estimate of the work conducted on invasive plants. We asked them to report annual expenditures on invasive plant control, monitoring, mapping, and outreach. These results are by necessity an extrapolation and a low estimate. Hundreds of organizations across the state work on invasive plants, from federal agencies to local “Friends of the Creek” groups. Many projects are severely underfunded.

Download a one-page fact sheet showing the results of our survey (pdf). We intend this as a “living document” and will continue to collect data for a more comprehensive estimate on the cost of invasive plants to California. We have presented this information to policymakers to help them understand the issue of invasive species.

Boat in hyacinth
Hyacinth diminishes recreation opportunites and impacts wildlife habitat

Photo courtesy Bob Case



For more information

Visit Cal-IPC’s Impacts of Invasive Plants webpage – includes why you should care, myths & facts, and what you can do.

Article from Cal-IPC News, Spring 2009 – Describes our survey and the economic impacts of invasive plants in more detail.

Cal-IPC Research Needs Assessment, 2009 – Section on Economic Impacts describes the studies needed to improve the understanding of invasive plants’ cost.

Related Links

Center for Invasive Plant Management, Montana State University – References with facts and figures on the economic impacts of invasive species.

USDA National Invasive Species Information Center – economic impacts webpage – Provides access to economic impact reports from throughout the country.

PlantRight – A voluntary, proactive program for the horticultural community to prevent invasive plant introductions through horticulture.