Assessing options for stream regulation using hydrologic simulations and cumulative impact analysis: Flathead River Basin, U.S.A.

Abstract

This study attempted to resolve regulation problems up-and downstream of Flathead Lake and on the lake proper. Members of a technical working group, representing eight water and wildlife management agencies, contributed 75 regulation scenarios they deemed necessary to conserve or enhance ecological (fish and wildlife) and societal (hydropower production, flood control, and recreation) resources for which they had management authority. The hydrology model simulated the effect of each scenario on system water balance; scenarios that were within the physical and legal constraints of the system were accepted for determination of cumulative impacts on resources. A multiattribute tradeoff analysis was used to assess cumulative impacts to key resources as a consequence of each regulation scenario (simulation) accepted for evaluation. Impacts were subjectively and independently quantified by each member of the working group following a point and importance weighting system agreed to a priori. Valuation of impacts was done on the basis of 36 technical studies of the effects of regulation on system resources. Impact valuations were summed to yield a variable referred to as weighted cumulative impact (WCI), where the highest, positive WCI indicated least cumulative impact on resources. Scenarios were then ranked in terms of WCI. When ecological resources only were evaluated, the preregulation Flathead Lake scenario generated the highest WCI. However, when all resources were considered, scenarios ranked very differently but a preferred alternative was identified by virtue of its highest WCI. This interactive process of hydrology simulation and computation of cumulative impacts mediated resource conflicts and served as an important tool in deriving water management recommendations in the Flathead River Basin. The process may be useful elsewhere.

Ecological effects of river regulation on mammals and birds: A review

“…Most studies on the effects of hydroelectric development on mammals and birds are characterized by speculations about the likely effects of river regulation. There are examples of attempts to predict the total damage by regulation (Jourdonnais et al, 1990) and to predict which mechanisms will be affected (Ballard et af., 1987;. Most predictions are, however, very general and give the type of change at most, not its magnitude (but see Jourdonnais et al, 1990).…”

Mitigating the impacts of stream and lake regulation in the flathead river catchment, Montana, USA: An ecosystem perspective

“…For example, the pattern proposed by Jourdonnais et al (1990) (Figure 7) would be vastly improved if the day-to-day 'yo-yo' operations (i.e. the wide operational windows) were curtailed.…”

“…A great deal of research has been done over the last decade to determine the effects of flow and lake level regulation by hydropower dams (i.e. Kerr, Bigfork, and Hungry Horse Dams: Figure 1) on biophysical attributes of the Flathead River-Lake ecosystem (cJ: Jourdonnais et al, 1990). Some 50 scientific papers and management reports include data and interpretations of ecological effects of water the annual hydrologic pattern is distinctively maximized in May-July by spring snowmelt in the mountain headwaters of each sub-catchment.…”

The Three Gorges Project: How sustainable?

“…These include contributions originating from systems thinking approaches (Jourdonnais, 1990) and indigenous knowledge. Wolf (2000) identifies indigenous examples of alternative management approaches evident in customary practice.…”

“…Although it follows that value is most commonly attributed using monetary equivalents, stakeholder bias is evident in the value attributed to a human life for example, or the extinction of a species (Berkes and Folke, 1994). Jourdonnais et al (1990) identify the differing importance of ecological and societal resources and adopt a weighted cumulative impact approach for their analysis. The subjectivity involved in attributing value or weights, creates much tension and conflict regarding sustainability assessment using a monetary basis.…”