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.. ,. I ~ .: Ii::: i'.I'.. 1, j,. 'I' j;;::." :l/;ii. Ip).:. :r: 38 PACE ENVIRONMENTAL LAW REVIEF' [Vol. 11 the passenger pigeon, such rapid disappearance o. a speCIes once so abundant would be almost beyond beliei'.' Despite their reputation as trash fish, both razorbacks and squawfish were eaten by Native Americans and early white settlers,lO and razorbacks were commercially fished and marketed in Arizona until the 1940s.11 Today, however, none of the four species are valued by anglers,12 although all of them can grow to be quite large. The squawfish, for exam- ple, the largest member of the minnow family in North America and the largest of the endangered river fish, reaches up to 1.8 meters in length and can weigh 36 kilograms. 13 The other endangered river fish are slightly smaller. None of the four species are brightly colored or strikingly marked. They are neither majestic nor cuddly, and would be oflittle interest to makers of T-shirts or toys. The decline of the river fish was caused by a complex and interconnected set of habitat changes wrought by the many dam and diversion projects in the Colorado River basin.14 Perhaps the most significant of these changes was the dams' alteration of the natural hydrograph15 of the basin's rivers. In their natural state, flows in western rivers peak in the spring with the melting of snow in the mountains and main- tain a low and stable flow at other times of the year.16 Flows in dammed rivers, however, peak in the summer and winter months, when demand for electricity is highest, and flows at other times fluctuate much more widely than in free-flowing 9. Id. 10. W.L. Minckley et al., Management Toward Recol>eT)' of the Razorback Sucker, in BATI'LE AGAINST EXTINCTION, supra note 2, at 303,307-08; Harold M. Tyus, Ecology and Management of the Colorado Squawfish, in BATTLE AGAINST EXTINCTION, supra note 2, at 379. 11. Holden, supra note 2, at 44. 12. Id. 13. Tyus, supra note 10, at 379. 14. For a discussion of these changes see, e.g., Flaming Gorge Opinion, supra note 6 at 6-24; Wydoski & Hamill, supra note 2, at 124. 15. "A stream hydrograph shows the discharge of a river at a single location as a function of time." CHARLES W. FE'ITER JR., APPLIED HYDROGEOLOGY 37 (1980). 16. Wydoski & Hamill, supra note 2, at 124. 1993] nver sy sin's riv tempen gered ri are key ture, f hydrogI ers' hye the fish ThE rectly t reservOJ routes, occupIel int:tQdw ters - : gered ] habitat Thl caused prod uct Under water u wasted granted water t benefici miners the firs" right a! .j '~ ~ 17. Fl 18. W 19. Sf (humpbac 20. W 21. R( 22. W 23. Sf Conservat -!l', -,. -~ ~ .i -;: :i