Copper Findings in Smith River Estuary Tributaries & Effects on Salmon

Estuaries are better known as the nursery of the sea. They provide critical habitat for marine animals during their early life stages in their brackish environment, offering abundant food and protection from predators. These unique coastal ecosystems are extremely biodiverse, supporting a wide array of species, contributing significantly to overall marine and freshwater biodiversity. The Smith River estuary specifically supports many threatened species, such as Chinook and Coho Salmon, Tidewater Goby, and smelt.

The Mouth of the Smith River (Smith River Estuary) or “Nii-li” in the Tolowa language, the first peoples of Smith River by Allen J. Schaben

Unfortunately, the community of Smith River, where the estuary lies, is heralded as the ‘Easter Lily Capital of the World’, producing nearly 90% of the world’s Easter lily bulbs. Easter Lily bulb farming requires virtually sterilized soil to keep nematode worms, fungus, and just about anything else from eating or deforming the lily bulbs. To prevent naturally occurring creatures in the soil, farmers apply 300,000 pounds of pesticides annually to a small acreage of coastal floodplain lands that leach directly into the estuary, and thus the ocean and Wild and Scenic Smith River. The pesticides used on these floodplains include 1,3-dichloropropene (1,3-D), metam sodium, copper hydroxide, diuron, ethoprop, napropamide, permethrin, phorate, and others.

Many of the products used in the Smith River estuary listed above are currently on the state of California’s Proposition 65 list of chemicals known to cause cancer and/or identified by the National Marine Fisheries Service as harmful to salmon. A recent Smith River Plain Surface Water Quality Monitoring Report conducted by the North Coast Regional Water Quality Control Board was released, showing predicted copper toxicity risk through the Biotic Ligand Model at nearly every estuary tributary that was monitored, with the exception of Rowdy Creek. This means that with the 300,000 pounds of pesticides that are poured into the Smith River Plain to cultivate lily bulbs, farmers are actually exceeding the allowable limit that is seeping into the waterways adjacent to the fields (shocker!).

The Biotic Ligand Model (also referred to as BLM in the Smith River Plain Surface Water Quality Monitoring Report) is a computational tool that predicts toxicity of metal such as copper (one of the chemicals applied to the Smith River Plain) to organisms by considering the water’s chemistry and how it affects the metal's availability to bind to the “biotic ligand” receptor on an organism. This calculation accounts for factors that compete with or enhance toxicity, like pH, dissolved organic carbon, and other ions, thus allowing a more accurate and site-specific measure of toxicity than simply looking at the total metal concentration in the water. 

Accurately measuring dissolved copper that can bind to fish in the estuary and tributaries is significant because copper can impair or destroy neurons that are associated with a fish's ability to smell and detect movements in the water. It has not been found that fish have acclimated or adapted to life with these functions impaired. For example, a salmon’s sense of smell is important for it to be able to migrate throughout the river basin and to the ocean during the various critical stages of a salmon’s reproductive life. Additionally, these impaired functions are vital for them to be able to detect predators and pursue prey.

This model was also used to find a correlation between copper toxicity and acidification of the water coming downstream from the farms. Additionally, other pesticides applied to the lily bulb fields have similar impacts on fish’s systems. Diuron, imidacloprid, and Ethoprop are also known to impact a fish’s growth early in its life, and overall metabolism and health. Between the copper toxicity, thus increased acidification, and the Diuron, imidacloprid, and Ethoprop, this brings forth a compounding effect for fish called synergistic toxicity; when the combined effects of different chemicals pile on each other and have an overall effect that is far greater than you would expect from just one chemical.

Overall, the SWAMP (Smith River Plain Surface Water Monitoring Report) does recommend reducing pesticides and copper use, investigating the low pH water running off the fields, and field practices to stop the pesticides from getting into the water, such as increased buffers between the lily bulb cultivation fields and the streams.

What will effectively help the fish in the Smith River estuary is implementing zero discharge requirements from farmers and disallowing the 300,000 pounds of pesticides from being applied annually to the coastal plain.