Water Quality Monitoring by the Hoopa Tribal Environmental Protection Agency 2008–2012 PREPARED BY

This report presents the results of the Hoopa Tribal Environmental Protection Agency’s (Hoopa TEPA) water quality monitoring within the Hoopa Valley Indian Reservation for the years 2008 to 2012. Hoopa TEPA is a member of the Klamath Basin Tribal Water Quality Work Group (Work Group) and has worked to develop and implement shared water quality monitoring protocols with the Yurok Tribe and the Karuk Tribe who also conduct monitoring in the Trinity and Lower Klamath basins.

Samples were collected by Hoopa TEPA staff at two stations: the Klamath River at Saints Rest Bar and the Trinity River at Hoopa. The beginning and end of the sampling season varied by year, with samples collected from mid or late May through early or mid-October. Sampling frequency was generally monthly in 2008 and bi-weekly (every two weeks) in 2009-2012. Water samples were collected and analyzed for nutrients, chlorophyll-a, algal toxins, phytoplankton species (i.e., free-floating algae), and other chemical parameters. Periphyton samples (i.e., algae attached the riverbed) were collected by scraping a fixed area from river cobbles and then analyzed for chlorophyll-a and algal species. The laboratory analyses of the water and periphyton samples were performed using funds awarded to the Klamath Basin Tribal Water Quality Work Group by the U.S. EPA Region 9.

In the report, sampling results are compared with the water quality standards from the Hoopa Tribe’s Water Quality Control Plan. Concentrations of most nitrogen, phosphorus, and carbon parameters were almost always higher at the Klamath River site than the Trinity River site. Exceedances of the Tribe’s nutrient criteria of 0.035 mg/L total phosphorus (TP) and 0.2 mg/L total nitrogen (TN) were common at the Klamath River site (67% and 60%, respectively) but rare at the Trinity River site (4% and 2%, respectively).