Functional Assessment Potential Future Drivers
Variable / Sub-Variable Existing Condition Increasing Municipal Water Use Urbanization Warm & Wet Climate Future In-Between Climate Future Hot and Dry Climate Future New TMDs Increased Reservoir Capacity Wildfire
Streamflows
Base Flow: Dry Year B Onset and peak snowmelt shift earlier in season, exacerbating severity and duration of late season low flow spells Onset and peak snowmelt shift earlier in season, coupled with increasing air temperatures, exacerbating severity and duration of late season low flow spells Onset and peak snowmelt shift earlier in season, coupled with increasing air temperatures, exacerbating severity and duration of late season low flow spells Reservoir augmentation of late summer baseflows may somewhat mitigate climate-induced reductions.
Base Flow: Median YearIncreased TMDs drive additional declines in total available flow volume in typical years. B Low flow spells increase in severity and duration Low flow spells increase in severity and duration Low flow spells increase in severity and duration Increased TMDs drive additional declines in total available flow volume in typical years. Reservoir augmentation of late summer baseflows may somewhat mitigate climate-induced reductions.
High Peakflow FrequencyIncreased TMD diversions during high flow season further reduce the return frequency of high peak flows. F Upstream reservoir fills diminish peak flood flow magnitudes and frequencies Increasing probability of high flow peak event during high snow years Warmer climate future slightly increases peak flow magnitudes and variability, likely due to earlier melt and increased probability of rain-on-snow events Warmer climate future increases peak flow magnitudes and variability, likely due to earlier melt and increased probability of rain-on-snow events Increased TMD diversions during high flow season further reduce the return frequency of high peak flows. Upstream reservoir fills diminish peak flood flow magnitudes and frequencies
Peak Flow: Dry YearIncreased TMD diversions further reduce peak flow magnitudes, durations, or frequency in dry years. D Wetter and warmer climate future slightly increases peak flow magnitudes and variability; increased peak flows may be accompaied by shorter duration of high flows. Flow losses from warming climate are outpaced by any potential precipitation increases Streamflow losses from warming climate result in declines in magnitude and frequency of peak flows Increased TMD diversions further reduce peak flow magnitudes, durations, or frequency in dry years. Upstream reservoir fills diminish peak flood flow magnitudes and frequencies
Peak Flow: Median YearIncreased TMD diversions further reduce peak flow magnitudes, durations, or frequency in typical years. C Wetter and warmer climate future slightly increases peak flow magnitudes and variability Increased TMD diversions further reduce peak flow magnitudes, durations, or frequency in typical years. Upstream reservoir fills diminish peak flood flow magnitudes and frequencies
Total Volume: Dry YearIncreased TMD diversions further reduce total annual flow volume in dry years. D Total streamflow declines due to warming temperatures (increased vegetation ET demand, lower soil moisture, longer growing/irrigation season) drive overall streamflow declines Total streamflow declines due to warming temperatures (increased vegetation ET demand, lower soil moisture, longer growing/irrigation season) drive overall streamflow declines Increased TMD diversions further reduce total annual flow volume in dry years.
Total Volume: Median YearIncreased TMD diversions further reduce total annual flow volume in typical years. C Total streamflow declines at higher watershed stream reaches due to warming temperatures (increased vegetation ET demand, lower soil moisture, longer growing/irrigation season) are balanced or slightly exceeded by gains from precipitation increases Total streamflow declines due to warming temperatures (increased vegetation ET demand, lower soil moisture, longer growing/irrigation season) drive overall streamflow declines Total streamflow declines due to warming temperatures (increased vegetation ET demand, lower soil moisture, longer growing/irrigation season) drive overall streamflow declines Increased TMD diversions further reduce total annual flow volume in typical years. Total streamflow declines due to warming temperatures (increased vegetation ET demand, lower soil moisture, longer growing/irrigation season) drive overall streamflow declines
Streambed Sediment
Continuity and TransportFurther decreases to peak flows and total volumes decrease sediment transport capacity and loads from current levels. A Decreased total volumes and base flow magnitudes salter total annual sediment transport capacity Further decreases to peak flows and total volumes decrease sediment transport capacity and loads from current levels. Changes in streamflow regimes including declines in peak flows and total volumes due to reservoir operations further alters sediment transport regimes Increased watershed responsiveness can drive increased peak floods and sediment delivery, impacting channel shaping processes like erosion/aggradation rates and seasonal sediment transport
Flushing FlowsIncreased TMDs diversion volumes further reduce peak flows (geomorphic flows) and total annual flow, decreasing the frequency and duration of flushing flows. C Increased TMDs diversion volumes further reduce peak flows (geomorphic flows) and total annual flow, decreasing the frequency and duration of flushing flows. Changes in flow regimes drive decreased frequency of discharges at or above sediment mobilization thresholds
Water Quality
Metals Further decreases in spring high flows may reduce metal dilution capacity below the Eagle Mine. F Further decreases in spring high flows may reduce metal dilution capacity below the Eagle Mine. Reductions in spring flows or timing reduce dilution capacity for pollutant loads Runoff from burned areas increases dissolved metals loads to streams
Nutrients A Runoff from burned areas increases nutrient loads to streams
Temperature A Increasing air temperatures and decreasing summer/fall baseflows creates increasing temperature risks for aquatic life Increasing air temperatures and decreasing summer/fall baseflows creates increasing temperature risks for aquatic life Reservoir management frameworks that include summer/fall baseflow augmentation may somewhat offset temperature risks from warming air and lower late seasons flows
Riparian Areas
Floodplain physical condition B
Riparian vegetation B
River Form
Channel Structure and Dynamics B Increased sediment fluxes impact channel shaping processes including aggradation rates and seasonal sediment transport
Aquatic Habitat
Habitat Structure B Increased sediment fluxes degrade inchannel habitat quality including spawning sites and macroinvertebrate habitat
In-channel Hydrologic ConnectivityIncreased TMD diversions decrease total annual flow volumes, potentially decreasing in-channel connectivity during low flows. A Baseflow declines reduce stream network connectivity during late summer and fall, potential impacts to refuge seeking movements, migration, and spawning activity Baseflow declines reduce stream network connectivity during late summer and fall, potential impacts to refuge seeking movements, migration, and spawning activity Baseflow declines reduce stream network connectivity during late summer and fall, potential impacts to refuge seeking movements, migration, and spawning activity Increased TMD diversions decrease total annual flow volumes, potentially decreasing in-channel connectivity during low flows. Reservoir augmentation of late summer baseflows may somewhat mitigate climate-induced reductions.
Aquatic Life
Aquatic Insects B Low flow spells severity and duration still increase in summer/fall still under WW future, negatively impacting abundance. Low flow spells severity and duration increase in summer/fall still under IB future, negatively impacting abundance. Low flow spells severity and duration greatly increase in summer/fall HD future, negatively impacting abundance. Reservoir augmentation of late summer and early fall baseflows helps maintain habitat refugia and cooler water temperature Streambed Sedimentation and water chemistry impacts degrade physical habitat and water quality
Fish C Declining late summer/early fall flows place increasing pressure on instream flows, water quality (temperature, DO, nutrients, etc.), habitat connectivity Declining late summer/early fall flows and increasing air temperatures place increasing pressure on instream flows, water quality (temperature, DO, nutrients, etc.), habitat connectivity Declining late summer/early fall flows and increasing air temperatures place increasing pressure on instream flows, water quality (temperature, DO, nutrients, etc.), habitat connectivity Reservoir augmentation of late summer baseflows may somewhat mitigate climate-induced reductions. Increased sediment fluxes degrade inchannel habitat quality and water quality, including spawning sites and macroinvertebrate habitat