Copper is an essential trace nutrient that is required in small amounts (5-20 micrograms per gram (µg/g)) by humans, other mammals, fish and shellfish. In high enough concentrations, copper can be used to kill fish, algae, fungi and mollusks.  In fact, it is one of the most toxic metals to aquatic organisms and ecosystems. Copper does not bioaccumulate in the food web.

Hardness adjusted dissolved metal concentrations which were compared against the acute and chronic standards for the California Toxics Rule (CTR). Only copper and selenium were measured in concentrations that exceeded either of the CTR criteria and are presented here.

On the map on your left explore the proportion of water samples that exceeded regulatory standards for each region of the San Gabriel watershed for Copper:

-  Exceeded Acute CTR
-  Exceeded Chronic CTR
-  No CTR Exceedances