Graduation Date

Spring 2024

Document Type



Master of Science degree with a major in Natural Resources, option Forestry, Watershed, & Wildland Sciences

Committee Chair Name

Andrew Stubblefield

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Alison O'Dowd

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Margarita Otero-Diaz


Klamath River, Water quality, Northern California, Southern Oregon, Microcystin, Total nitrogen, Total phosphorus, Harmful algal bloom, Cyanobacteria, Cyanotoxin, River, Salmonid

Subject Categories

Natural Resources


The Klamath River tends to experience impaired upstream water quality, which improves downstream. Although this consensus is accepted, an updated spatiotemporal analysis of certain water quality parameters has not been conducted since 2017. With four of the Klamath River’s dams slated for removal by the end of 2024, it is critical to have an updated assessment of current water quality conditions from which to compare conditions following dam removal. In this study, total nitrogen (TN), total phosphorus (TP), and microcystin data from 2010-2021 were analyzed to determine concentration trends from Link Dam to the Klamath River Estuary.

Concentrations of TN and TP generally decrease with river mile, but nutrient levels in tributaries and reservoirs are more variable. Microcystin concentrations are generally highest in reservoirs. TN is generally increasing over time, while TP trends vary by site. Microcystin is generally decreasing or experiencing no trend, though some sites did not have enough data to complete microcystin temporal analysis. TN and TP concentrations consistently exceeded target level, and microcystin exceedances in reservoirs are often the most frequent and severe.

Based on this analysis, the mainstem Klamath River does tend to experience elevated nutrient concentrations upstream which improves downstream. The river, then, is “upside-down” in terms of nutrient concentration. The results of this study can be compared against future water quality monitoring and analysis efforts following dam removal, as evidence of the impacts of dam removal on water quality. This thesis is a small contribution toward the collective goal of understanding water quality in the Klamath Basin.


Thesis/Project Location


To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.