Overview of Scenario Results


Ten sets of scenarios (table 2) were tested with the Link-Keno water-quality model to provide insights into potential water-quality changes as a result of changes in operational or management strategies. Each scenario evaluated here affected water quality in different ways (fig. 22, appendix A). 


Scenarios 1 to 3 assessed the water-quality effects of meeting TMDL allocations and targets and were not associated with specific treatments or prescriptions. Rather these simulations explored systematically decreasing input concentrations of dissolved and particulate nutrients, organic matter, and algae until targets or allocations were met. These were the only scenarios that resulted in large decreases in dissolved organic matter (represented as DOC) in the Link‑Keno reach, especially scenarios 2a and 2b (fig. 22). Whether the levels of dissolved organic matter decreases assumed for these simulations are possible in this reach is uncertain, given that upstream watersheds have wetlands that typically have high concentrations of dissolved organic matter. These TMDL scenarios and analyses assessing whether water‑quality criteria would be achieved could be revisited in the future when or if specific treatment options to meet TMDLs are identified for evaluation. 


Scenario 5 evaluated particulate shunting, and simulated a significant decrease in water-quality conditions in the Link‑Keno reach. However, eliminating particulate material from the Lost River basin may improve water quality there, which could be explored in the future through additional monitoring, research, and modeling. Scenario 6 simulations focused on removal of particulate matter and algae at Link River and illustrated improvements in dissolved oxygen and other water-quality constituents in downstream reaches. The large improvements resulting from 90 percent removal of algae and particulate matter in Link River demonstrated the importance of that inflow to water quality in the Link‑Keno reach. Scenario 7 examined the effects of wetlands on water quality, addressing not only particulate matter and algae in the Link-Keno reach, but also changes to ancillary constituents, such as dissolved nutrients and oxygen (fig. 22). Scenario 8 examined the effects of flow routing changes. Scenario 9 assessed specific prescriptions aimed at improving dissolved-oxygen levels through mechanical means and water temperature effects related to riparian shading. Dissolved oxygen additions increased dissolved-oxygen concentrations, but had little to no effect on other water-quality constituents in the study reach (fig. 22). Riparian shading had little impact on water temperatures due to the wide river channel compared to the height of native trees that would potentially grow along Keno Reservoir. Scenario 10 demonstrated potential changes to the Link-Keno reach under a future warmer climate. If warm water temperatures remain an issue in the Klamath River, alternate management strategies to provide microhabitats with cool-water refugia may be useful.


The details of model scenario set-up have direct implications on model results. Because specific details of water-quality prescriptions and management strategies for this reach have not yet been determined, many of these simulations were exploratory, examining the range of effects and analyzing general temporal and spatial patterns. These results and the existing model can be used to assist in assessing, prioritizing, and selecting management or treatment options as well as helping to refine specific plans.


First posted July 24, 2013