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Table 3f Recent projects, in which restoration of some component(s) of natural flow regimes has occurred or been proposed for specific ecological benefits. - Location Trinity River. CA Truckee River, CA Flow component(s) Mimic timing and magnitude of peak flow Ecological purpose ($) Reference ' Rejuvenate in-channel gravel habitats; restore Barinaga 1996~ early riparian succession; provide migration . flows for juvenile salmon Restore riparian trees. especially cottonwoods Klotz and Swanson 1997 Mimic timing, magnitude. and duration of peak flowJ and its rate of change during recession Owens River, CA Increase base flows: partially restore overbank flows Rush Creek. CA (and other Increase mJnimum flows tributarfes to Mono Lake) Restore riparian vegetation and habitat for native fIShes and non..native brown trout . Restore riparian vegetation and habitat for waterfowl and non. native fishes Oldman River and tributaries, Increase summer flows; reduce rates of. R.estore riparian vegetation (cottonwoods) southern Alberta, Canada postflood stage decline; mimic natural and cold..water (trout) fisheries flows in wet years Green Riv~r, ur San Juan River. UTINM Gunnison Rivef't CO Rio Grande River. NM Pecos River, NM . . Colorado River, AZ Bill Williams River, AZ (proposed) Pemigewasset River, NH Roanoke River. VA Kissimmee River. FL Hill and Platts in press LADWP 1995 Rood et al. 1995 Mimic timing and duration of peak flow Recovery .of endangered fish species; enhan~e Stanford 1994 and duration and timing of nonpeak other native fishes flows; reduce rapid baseftow fluctu.. ations from hydropower generation Mimic magnitude. timing, and duration Recovery of endangered tlsh species _b of peak flow; restore low winter basetlows Mimic magnitude. timing. and duration Recovery of endangered fish species of peak flow; mimic duration and t1~ng of nonpe~ flows Mimic timing and duration of flood.. pl~n inundation Regulate duration and magnitude of summer irrigation releases to mimic spawning flow II spikes": maintain minimum flows Mimic magnitude and tim~n8 Mimic natural flood peak timing and duration Reduce frequency (Le.. to no more than natural frequency) of high flows during summer low-flow season; reduce rate of change between low and high flows durl~g hydropower cycles , Restore more natural patterning of monthly flows in spring; reduce rate of change between low and high flows during hydropower cycles MImic magnitude, .duration. rate of change, and tinting of high- and low- flow periods ' Ecosystem processes (e,g,~ nitrogen flux; microbial ~ctivity. ~tter decomposition) Determine spawning and habitat needs for threatened fish species Restore habitat ~or endangered fish species and scour riparian zone . Promote establishment of native trees Enhance native Atlantic sal~on recovery Increased reproduction of striped bass .Restore floodplain inundation to recover wetland functions; reestablish in-channel ha.bitats for fish and other aquatic species IIJ, Polos, 1997J personal communication, US Fish & Wildlife Service. Arcatat CA~ bF. PfeiferJ 1997. personal communication. US Fish & Wildlife Service. Grand ]unctiont CO. wood trees (Klotz and Swanson 1997) . primarily on one or a few species that live in the wetted river channel. Most of these methods have the nar- row intent of establishing minimum allowable flows. The simplest make use of easily analyzed flow data, of assumptions about the regional simi- larity of rivers, and of professional Recent approaches to- . streamflow management Methods to estim.ate. environmental flow requirem.ents for rivers focus December 1997 _b MalleS et at. 1995 Robertson 1997 Collier et 31. 1997 USCO-E 1996 FERC 1995 Rulifson and Manooch 1993 Toth 1995 opinions of the minimal flow needs for certain fish species (e.g.t Larson 1981). A more sophisticated assessment of how changes in river flow affect aquatic habitat is provided by the Instream Flow Incremental Method- ology (IFIM; Bovee and Milhous 779