7793 - Laserfiche WebLink

Home Browse Search

INSTREAM FLOW 99 iD the 1940's on four of the five streams that feed the lake, water levels at Mono Lake dropped sharply. Avian habitat provided by the marshes and islets of the lake diminished sharply. Shoreline recreational opportunities were adversely affected by diminished lake water levels. Off-site benefits of restoring surface water levels at Mono Lake per California household were $42 per annum, and represented 90% of the total aggregate value. The social opportunity cost of maintaining higher Mono Lake water levels was estimated to be $2.64 per California household per annum. Loomis et al.7 19900 estimated the benefits of reallocating San Joaquin River waters to maintain positive instream flows for this California river. The social costs of rewatering the streamreach in order to partially restore the San Joaquin River fall chinook salmon run include foregone agricultural output and hydropower. Loomis et al.3o show that the estimated nonmarket benefits of more than $2 billion per annum for restoring the San Joaquin River salmon run are significantly greater than the social costs. . Walsh et al.22 estimated the benefits and costs of having various Colorado rivers be officially designated by Congress as Wild and Scenic Rivers. The Colorado rivers in question would then become protected from development pressures by the Federal Wild and Scenic Rivers Act of 1968. They present important data on per capita benefits and costs for protecting these rivers; they estimate and use a miles-of- stream-reach-protected versus net-marginal-benefits-of-protection relation to calcu- late the optimal level of protection. The costs of protecting the river stem from foregone grazing, mining, and timber harvesting activities. In addition, two sizeable planned water development projects would be permanently forestalled. Irrigation water from planned impoundments is mentioned explicitly by Walsh et al.22 as one of the outputs of hypothetical development projects. They estimate that the marginal social benefits conferred exceed the marginal social costs of protection from further development for 13 Colorado rivers. The present value in 1983 of the net off-site benefits from protecting the three most valuable rivers including the Cache la Poudre, Colorado, and Elk Rivers for 50 years were $485 million at a discount rate of 7.875%. The present value for the net user benefits for the three rivers was $113 million.22 The large off-site nonmarket benefits estimated by Loomis et al.,7 Walsh et al.,22 and Loomis23 have sharper policy implications than earlier contingent value method on-site benefits studies. Note that the survey instruments of these three existence benefits studies clearly delineate a baseline reference condition. For example, the non market amenity in Walsh et al.22 is protecting miles of streamreach for certain carefully designated streamreaches from further construction of dams, reservoirs, and other water diversions or development that alters their free-flowing condition. The baseline condition is, therefore, the pre-1983 state of the rivers.22 The baseline condition in Loomis et al. 7 is a completely extinct salmon run. The salient issue is one of defining the amenity in relatively simple terms that facilitate the definition of the baseline condition. Kahneman and Koetsch,27 for example, estimate benefits for a broad environmental amenity that is so complex and multi-faceted that it is difficult to quantify amenity improvements, and therefore difficult to define the baseline. OFF-SITE BENEFITS AND HYDROPOWER The policy implications of recent studies employing state-of-the art techniques, large data bases, and carefully designed survey instruments to estimate similar instream