Pesticides & Herbicides 101

Pesticides are a group of chemicals used to kill or repel unwanted organisms, and herbicides are a type of pesticide used to kill plants. Glyphosate and other pesticides can impact both aquatic ecosystems and human health when they enter waterways.

Pesticides can harm or kill non-target organisms such as fish, amphibians, native plants, and aquatic invertebrates, disrupting food webs and degrading healthy ecosystems. Human exposure to certain pesticides has also been associated with serious health concerns, including cancer, neurological effects, and developmental problems, particularly for communities living near areas with frequent pesticide use. (Read more about pesticides on Beachapedia)

Pesticides & herbicides generally:

• Target how an organism functions instead of a specific species or pest
• Native plants can be harmed by herbicides sprayed for weeds, butterflies can be harmed by insecticides used for mosquitoes
• Break down into other chemical compounds
• Many chemicals collect in soil and take a long time to break down.
• Soil microbes break Glyphosate down into AMPA, which has a half-life of 121 days. Little is known about AMPA’s toxicity to the environment or humans.
• Are poorly studied for toxicity in aquatic environments
• The EPA has established aquatic life criteria (intended to protect 95% of non-target species) for fewer than 1% of 1000+ registered pesticides
• Are frequently applied as mixtures with other chemicals
• These chemicals can interact in unexpected ways, and we don’t know the impacts of these new combinations
• Are interchangeable by the people applying them
• Banning one kind of pesticide often results in a switch to another, newer, lesser-known pesticide, which comes with its own risks and harms. We need to pursue different pest management strategies that do not rely on pesticides.

How is this pesticide activity regulated in California? 

Because pesticides can greatly impact the health of our waterways, there are different regulations at the local, state, and federal levels. But these regulations are only able to protect our water if they are properly enforced.

On a Federal level, the Clean Water Act (1972) provides the framework for the Environmental Protection Agency (EPA) to regulate water quality standards and pollutant discharges into waterways. The National Pollutant Discharge Elimination System (NPDES) specifically controls discharges of pollutants through a permitting process. In California, this permitting system is implemented by the State Water Resources Control Board (SWRCB), which is a state agency within the California Environmental Protection Agency (CalEPA).

Ex. Orange County Public Works Herbicide Applications:

To hold an NPDES permit to discharge herbicides in waterways, OCPW must develop and follow an Aquatic Pesticide Application Plan (APAP), monitor and report on pesticide application rates, locations, and any observed impacts to water quality or aquatic life, and generally follow Best Management Practices (BMPs) to minimize pollution and protect beneficial uses of the waterway. This includes avoiding non-target organisms, preventing over-application, avoiding sensitive habitats, and more. You can read OCPW’s APAP document here.