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Show and stockpiled if necessary. Where investigations are under way to determine the presence and value of minerals in other reservoir sites, con- struction should similarly be deferred awaiting the results of such studies. Where minerals are dis- covered on valuable reservoir sites, effort should be made to mine out those parts affected by reservoir inundation at the earliest practicable date. Effort should also be made to determine whether or not inundation of a site necessarily forecloses future mining operations. In some cases, at least, reser- voir development may not be incompatible with later mining operations. It is thought that such a course will resolve con- flicts between use of reservoir sites and accessibility of minerals. Ultimately, if reservoir construction is considered essential but it conflicts with mining potentialities, the decision should be based on: (1) Comparison of benefits and costs. (2) For critically limited strategic minerals, ac- cessibility of alternative sources. (3) Recognition that reservoir operation in at least some instances could allow temporarily for exploitation of mineral deposits in the reservoir area, at such time as exploitation becomes desirable. streams, as well as destroying forage and range re- sources so as to seriously disrupt local range econ- omies. Some of these works are immediately up- stream from water projects, so damage is being done to public water supply and irrigation interests. Mining probably will increase as new transporta- tion facilities are provided. Lead and zinc mines close to the Canadian border are polluting the Columbia in that area, resulting in losses to public water, recreational uses, and asso- ciated values. Similar pollution already is serious in the Coeur d'Alene section and has rendered some streams unfit for many industrial uses. The reduction of ores in Canada, with attendant damage by air pollution to water and watershed values in the United States, has been resolved by treaty. However, a new source of air pollution with attendant killing of vegetation is expected in a new smelter on the headwaters of the Salmon River. Air pollution has also become a problem in the Vancouver, Wash., and Troutdale, Oreg., vicinities where aluminum reduction plant fumes have caused damage to farm crops, orchards, and other vegeta- tion. The effects upon water quality and sediment in local streams are not recorded. 6. Reservoir Sedimentation and Pollution from Mining Industries The Problem Are sedimentation and pollution from mining ac- tivities serious enough to handicap a full water de- velopment program in the basin, and if so, what policy should be adopted with respect to them? The Situation As mentioned in the previous problem, many valuable mines have been opened in the highly mineralized mountain sections of the Columbia Basin. In some localities the reduction of ores is associated with the extractive processes. At first, the damages done were so slight as to create no problem. With changing economic conditions, in- creased population, and heavy public and private investments in land and water, the damages to water resources are mounting. Placer mining and dredging operations in chan- nels have developed on a large scale in a few local- ities. In central Idaho and western Montana, these operations have greatly accelerated local erosion and created sedimentation problems on some Conclusions In general, mining pollution and damages to water and reservoirs by mining are at present not particularly widespread, although serious locally. The problem is growing as interest in water re- sources increases and as large investments are being made for various types of reservoir projects. Al- though provision is made in some reservoirs for sedimentation losses, it would appear that steps should be taken to prevent further damage. This might be through the provision of catchment or debris basins which would settle out the damaging material near the point of origin, as has been done in California.1 Release of smelter gases which kill the natural watershed cover also should be re- strained. In many instances, the returns from this form of pollution abatement are greatly in excess of costs. Mining industry in the Columbia area should be restrained from discharging mining debris into streams or channels, or permitting poisonous sub- 1 This in general should be the responsibility of the min- ing industry. However, in the national defense emergency situation prevailing in 1950 and 1951, the effect of control requirements upon marginal mines for strategic materials also must be considered. 53 |