Take Home Message

In all scenarios stream flow peaks are reduced and occur earlier in the year.

Key Findings

  • Stream flows respond to warming conditions with shifts of spring runoff to earlier in the season and reduced 'peak' flows.
  • Shifts in the timing of flows can be seen by looking at only one scenario as it progresses through the study period, or comparing the three scenarios at the end of the study period.
  • Stream flows under hot-dry scenario at the end of the study period represent a basin receiving its precipitation primarly as rain.


The timing and magnitude of stream flow in the Big Wood basin is controlled by a number of factors - climate, snowpack, timing of releases from Magic Reservoir, surface water/groundwater interactions, demand from natural vegetation, agricultural and urban uses, among others. Most of these factors (except surface water/groundwater interactions) are consider in the scenario models.

The results below show some of the results related to stream flows. The first and second chart show the annual stream flow profile for various decades for Camas Creek and the Big Wood at Hailey for future 20 year periods, with results from each climate senario.

The top chart represents four hydrographs: the historic (black) low change, warm and wetter, and hotter and drier than historical conditions. Under the low change scenario this is a shift in the timing of flows but still has a strong spring time peak flow. In the warm/wet scenario, timing of peak flow is diminished and occurs earlier in the year as a result of more volume running off during winter. The hot/dry scenario indicates a basin that is primarily rain driven, where precipitation falls primarily as rain with little stored as snowpack.

The equivalent information for Big Wood at Hailey is shown below: