Water Resources Development HERBERT S.RIESBOL -
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BUREIU OF RECLAMATION, U. S. DEPARTMENT OF RIB INTERIOR. DEN&
COLO.
The water scamity problem of the westem stat- L n.est built s economic necessity for full development and critical in many -om and will increase with timb if systems, generally expanding the facilities of the natives. conserva;tion of the water rep-nt climatic conditions continue. This, plus the growth of cities, industry. and adcultule, placr an unAcreage i r r i g a t e d at the sources with which nature has endowed our nation i6 pncedented demand on the existing water msouxes. Spanish missions was small, The development, m-uee, and salvage of a d d i t i o d water yet it provided an important particularly evident in the western United States. The supplies is already being executed, but thim will not be object lesson for Americsn industrial, agricultural, and enough. The diversion of water from other basins, the and European settlers who exchange of water among numerous basins, and the adbegan arriving in California commercial economy which i8 jmtment of legal right. d be necessary if the water rein the 1830’sand 1840’s. now being built on the utilieation of the immensely souavailable are to be utilized to the h a t int-t of Modem irrigation received all. This problem of water supply, although local in naits first great impetus in July valuable natural resources of tule. is far-reaching in effecton sectional and national sa1847, when the Mormon our western states is severely limited by the availability of cial and economic lib. The problem L rsal and must be pioneers, newly arrived in -0gnimSd immediately by all-not just by thBraups the Bonneville Basin a t Great water for homes, municipalities, industrial processes, &ted--ss the fortun- of one gmup iduence all others Salt Lake, diverted water in both the East and West. In the int-ts of the from City Creek t o land befanning, snd hydroelectric tional economy and mcurity. all measurea that will fully hgplowed. Fromthis initial power generation. The full utilization of the utilize and salvaae experiment and the object . water rsaources must be taken. basic natural reaoumea and lessons of the early Indian the accompanying industrial and Spanish works have grown the vast irrigation enterprises and accompanying fwd and commercial expansion cannot precede the availability of processing industries of the western United States which water and electrical power. Long-range cooperative thinking and have created modern, civilized communities of people. planning for the integration of water resource development and Historically, the early d&velapment of western industry was industrial expansion is essential to achieve the rapid and concurin mining. The latter half of the nineteenth century eaw a sharp rent utilization of tbese basic natural resources in order t o “prorim in the mining industry with an almost equally sharp decline vide for the common defense”and “promote the general welfaFe.” around 1900. The location of mills and smelters in virtually all The important influence a reliable water supply has on. the cnaes has been governed by the accessibility of a firm water supsettlement of a region in creating permanent communities is a p parent throughout the turbulent history of the arid West. The ply for the various ore d u c t i o n proceaaes. The long hauls of raw material t o the smelter from the mines indicate the selective location of both prehistoric and historic communities has been processes that determined their location. I n more recent years detennined by the available BOUIC~S of water. The great drought the introduction of electrical power has facilitated mine operations of the thirteenth century caused the earlier inhabitants in tbc and reduction methods, but still the development of the vast Southwest to evscuate-their settlements for a m with a more wealth of minerals is being retarded due t o shortages of cheap reliable water supply. The later invasion by t,he Spanish, with power. their mission construction and population iuereaae, generally A strict code of law and ethics governing the right t o the use located a t the previously established Indian villages in order t o of water in the western states has developed as the result of t b m take advantage of their water sources. With the advent of the vital needs and the gradual settlement by peoples of divers early American settlers, many new communities appeared as a result of military, mining, and ranching activities. All these origins. The power of the state and federal governments t enact laws for the control and administration of water within groups attempted t o base their location selection on existing their respective boundaries is derived from the police powers of water supply of sufficient stability t o ensure permanent settleour federal constitution. ments. The water right which attaches t o a watercourse is a right t o M a t of the development and expansion nf the villages, towns, the use of the flow, not t o private ownership of the water. The and cities of the West has occurred during the past 75 years. western law of water rights embraces the common-law doctrine of Cities such as Helena, Portland, and Boise have grown with a r i p a r b rights, the statutory doctrine of prior appropriation, water supply which has been adequate from natural sources, and cnmbinations thereof, Under the strict riparian doctrine, but others as Los Angeles, San Diego, and Denver have felt the taken from the common law of England and generally applied in pains of outgrowing the natural water mpply of their original eaetern states, the owner of riparian land is entitled t o have the system. This h a neceasitated the importation of water by means stream Bow by or through his land undiminished in quantity or of aquedueta, tunnels, and canals from other watersheds t o meet quality except for the requirements of domestic and household the needs of these expanding population centers. purposes and the watering of fsm animals. In the Weat the The growth of a stable agricultural economy in the western doctrine bas been modiied generally to allow each proprietor t o United Staten has been dependent on the development of irrigamake reasonable use of the water for the irrigation of his riparian tion systems. These system have been instrumental in guaranland. The need for a doctrine laying greater emphasis on beneteeing a firm water supply with a minimum of water shortages. ficial use and affording protection t o enterprises based on the The Catbolic Fathers who established missions in the South-
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I N D U S T R I A L A N D ' E N G I N E E R I N G CHEMISTRY
Figure 1. Major River Basins of the West feasibility of diverting waters and applying them to lands, whet her or not contiguous to watercourses, soon became apparant for the conditions of the Kest. The appropriative principle in the form in which it is now recognized throughout the West sprang from the requirements of a mining region. The appropriation doctrine rests on the proposition that heneficial use is the basis, measure, and limit of the appropriative right. The first in time to put the water to heneficial use, rvit,hout limitation of the place of use t o riparian land, is recognized as the first in right. Neither the diversion of water alone nor the intent alone will suffice to vest an appropriative right. Perfected only by use, the right is lost by abandonment. Similarly, under provisions of many state statutes, forfeiture will follow failure to use beneficially for a specific t,ime. The right to the use of ground water is in a somewhat different category from that of surface waters, the rules applicable to surface watercourses are generally applied only to defined underground streams. The principles governing ownership and right to the use of percolating ground m t e r s have been developed mainly by the courts. I n t'he absence of statutory declaration, the tendency has been to apply the English common-law doctrine of absolut,eownership on the part of the owner of overlying lands. However, as state codes have been enact'ed, they have also recognized the American principle of reasonable use and in some cases have applied the appropriation doctrine. Every interstate \vestern stream of any magnitude has its own law. Rights to the use of the waters of such streams are subject t o the constitutions, statutes, treaties, compacts, and court decisions of the United States and of the states through which the stream flows. I n addition, on those streams where there are federal projects for irrigation, flood control, hydroelect'ric power generation, navigation, or multiple purposes, there may be ob-
Vol. 43, No. 12
ligations arising from contracts between federal and local agencies that have an important' bearing on both public and private uses of water. The total of composite authority, right, and obligation derived from these various sources constitutes the law of the river. The majority of the people in the United States, through their elected representatives in the federal congress, have recognized the nation's responsibility for t'he full development of natural resources in the interest of national prosperity and security. To that' end, federal legislation has initiated and legalized federal aid to water resources development. Such legislation is based on the Constitution of the Cnited States which grants to the federal government certain powers bearing on interstate streams. Notably these include the power to regulate commerce among the several states and t o promote the general welfare. Aided by the Federal Land Laws and the general availability of surface and ground ivater, rapid progress was niade in irrigation during the nineteenth century. llillions of acres were selected, purchased, and developed by individual or cooperative effort and right,s to the use of easily divertible u-ater were established. The rate of growth, however, began to slow down, drawing attention to certain obstacles which might be removed by the federal government and which, if removed, might stimulate further expansion by individuals and stlateaid. The Reclaniation Act, passed on June 17, 1902, authorized the Secretary of the Interior to locate, construct, operate, and maintain works for the storage, diversion, and development of waters for the reclamation of the arid and semi-arid lands of the ITest. By this and subsequent legislation, especially the Reclamation iict of 1939 and its amendments, fuller utilization of the land and water resources was made possible. In 1928, the Boulder Canyon Project Act essentially began the era of multiple-purpose projects, providing a definite plan for the conservation and use of the many related features associated with mater development structures. The Bureau of Reclamation, acting pursuant to this legislation, beare the prime responsibility for the federal government in working with the \Testern states and their people in water resource development. The general objective of the federal government in making water resource development investments is t o achieve the maximum sustained use of the surface water and ground water supplies, based on sound business and engineering principles, in order to promote a continuing high level of national prosperity. Irrigation policy is directed primarily toward reclaiming arid land in the West, and flood control policy is aimed a t safeguarding property, life, and economic stability of communities. These ohjectives and policies, along Jyith similar thinking in hydroelectric power production, soil conservation, sediment control, navigation, pollution and salinity control, fish and wildlife propagation, and recreation provide the basis for the present-day concept of basin-wide development of multiple-purpose projects. In carrying out these objectives and policy, it is recognized that the areas of abundant water and power supply should serve areas of deficient supply and great physical and economic need. Also, each dam site represents a nonreplaceable national resource which must be fully utilized within the limits of sound business
December 1951
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INDUSTRIAL AND ENGINEERING CHEMISTRY
and engineeringprinciples, 80 88 to fulfill all the basic multiple-use requirements. In all water m u m e planning the basic existing requirements, such 88 the need for improved municipal water supplies and sewagedispoeal facilities, the fimning-up of existing agricultural water mpplies and the power supply, must be satisfied before entering into an expansion program for the basin or considering exportation of water from the basin. Resemtions can then be made for the VW~OUEamounts needed to satisfy forecasted future requirements. The stage of development and the national requirement~for ow natural m u r c e a have reached a point where the mpplies and demands, bbth present and future, must be viewed critically and fitted into a realistic and systematic development program. Within the past 20 years, natural resource development and planned uee of these resowces have expanded to include entire river hasine. Within the past few-years, largely as the result of the Flood Control Act of 1944, and in order to attain the greatest m o d n a t i o n possible bekween the many basin improvementa and water we pmgram~, river basin committees have been established for moth of the major western rivers. These committees include representatives of each of the states within the basin and of all federal departments and agencies concerned with water re'mum development. Througb such an instmment a procedure has been c m t e d which has mccespfully prevented work duplication, coordinated development idem, and has maintained close contact with thepeople, political and civic leaders, press, and commercial and industrial interests of each basin. Also, these committees have extended the multiple-purpose concept by mutual participation and cooperation. Through such joint efforts,water resourceplslnoingbecomes truly b i n - w i d e without s e I i 3 devotion to one type of n e or to the interests of one group. The s o m e s of water for development witbin the 17 western states lie largely within the five major river basins of the Columbia, Colorado, Missouri, Rio Grande, and the Sacrament63an Joaquin, beside the Gulf of Mexico drainages, as shown in Figure 1. A few stresms of relatively high flow and limited withiubasin we, such as the Klamath River of Califomis, and the Rogue River of Oregon, Bow directly into 'the Pacific Ocean from the c a t range of. mountains, and, consequently, offer opportunity' for exportation of water to other basins. The Great Elmin of N e e and Utah pm?enea few &Rams of any significance. The average annual Bow from all surface streams in the West has been around 390,000,000acre-feet. If only about half of this water cotild be brought to the land in the right places, it would be mom than enough to supply the almost 4O,ooO,ooOirrigable acre8 with a full water supply. Unfortunately, much of this exreaa oecura where suitable land is not available or where such projects are not feaaihle. Before this water can actually be &e available for mch ufa i t will he nece'mry, h t , to 8ecure rights to its we on the basis of redivi~ionof existing stream flows, and, secondly, t o plan, deaign, and build on a selective basis the extensive and cothly works necessary for regulstion, diversion, and conveyance.
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MIasouRl RIVER BASIN The largest basin in areal extent is t.he Missouri River Basin with its 529,000 square,milee-one sixth the total land area of the United State-cnnsisting of the northern portion of the Great Plaina south of the Canadian border plus the eastern slopes of the Rmky Mountains north of central Colorado. Stream flow from the bssin over the paat 50 years ha^ averaged annually some 59,000,000acre-feet. Plana have been made to u t i l h fully the flowa of the Misaouri River Basin for multiple-purpose development. 'Io accomplish this, it will be neoesaary to conatmct reservoirs to regulate the variable stream BOWS. Such storage of water will result in some water loss through evaporation, but will increase the usable aver-
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age yield of the river many times.
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the Miemuri River above Sioux City, Iowa (adjusted for present-day levels of development) has been shout 24,500,000acre-feet since 1898. During the drought years, 1930-41, the average adjusted flow was only a little above 15,000,000 acre-feet. With regulatory reservoirs, annual requirements of nearly xI,ooO,WO acre-feet can be supplied with the exception of limited shortages that can be tolerated during the greatest drought years. These requiwments include municipal and industrial demands, agricultural ne&, navigation, and public health and stream @an;tation requirements. Below Sioux City, mfficient water appears to he available for municipal, industrial, and irrigation developments on the Platte and Kansas Rivers, using almost 2,500,000 acre-feet if regulatory storage SUWhS waters are - is provided. . available for foreseeable developments on the other tributatiew and on the "main stem" below Sioux City to the mouth. When fully developed under present plaas water will be provided for nome 5,ooO,ooO acres of new laud and supplemental water for over 1,000,ooO acres now inadequately irrigated, municipal and industrial a.ater for estimated future needs, and navigation requirements in most years. The irrigation of numerous a m 8 scattered widely over the basin will firm-up an unavoidably preosrious dry-farm and graeing economy by adding the atabilieing influence of lands with ensured crops and high yields Hydmelwtric power in the Missouri Basin bas been and will continue to be a significantfactor tothe growthand stabilization 01 the region's economy. While development has been slow, pri. marily due t o the small power potentials, simble blocks 01 lawer-cmt energy will be available through the comprehensivc basin development. At pwsent, federal plants have an installea capacity of 158,ooO kilowatts; by 1955 a fivefold increase t c 809,000kilowatts is scheduled. Ultimately, the federal installation will be about 3,200,000kilon,atts capable of producing about 13 billion kilowatt-hours annually.
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COLUMBIA RIVER BASIN
T h e Columbia River Basin yielda the greatest stream run+@ in the United States other than the Missiaeippi River. Thi Columbia, withadrainageareaof259,000sqnaremil~,djacharger annually an average of aome 170,000,000acre-feet. Surveys havt indicated that there is mare than enough water to satisfy the bsein's ne& under ultimate development. However, additional reservoir storage is needed to utili% this resource for development purposes. The already developed 3,7W,000acres of irrigated land and other uses could be aupple mented by plana already made for development of the Columbii River. The construction of almmt 27,000,000 acre-feet of stor age capacity would regulate the flows for we on an additiona nearly 4,000,000 acres of land plus aupplemental supply to exist ing irrigated lands. Even with such development, a large part of the Columbii River flowa will continue to be available for further use and development as the needa a r k . At the same time it is recognized that on some of the tributaries of the Columbia virtually full development of existingmppliesis beingspproached. The basin's economy depends heavily on the present we of water. However, only a fraction of this resource has been put to work, Of the land which feasibly can be irrigated, only about one half is receiving adequate water, leaving some 5,400,000 acres yet to be served in whole or part. Only one 6fth of the tremendous hydroelectric potential has been developed despite the m e n t large installations at Grand Coulee and Bouneville Dams.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Regardless of nearly 200 existing hydroelectric power plants with an installed capacity of 2,250,000 kiloivatts, and because of the industrial growth that low-cost power has fostered, today that region is one of two in the country most deficient in power. At the present time there are being proposed new generating plants that ultimately would add almost 3,000,000 kilowatts of capacity, relieving the existing conditions and aiding in further industrial expansion. CENTRAL VALLEY BASIN OF CALIFORNIA
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The Central Valley Basin of California, n-hich includes the Sacramento and San Joaquin Rivers, has experienced much progress in the ut.ilization of its water resources. The principal use of the nearly 60,000 square miles of land has been devoted to irrigation developments, chiefly through private and local community organization efforts. For such purposes the development of ground water has been a predominant supply source; however, in various sections this supply is rapidly becoming of concern, because of overpumping. The recently completed Central Valley Project of the Bureau of Reclamation will be a valuable asset t o the existing agricultural economy by providing supplemental water supplies. However, this project is only a first major step in the development of the water and land resources of the Central Valley Basin. Storage, interbasin, and transbasin projrct plans Tyill enable the remaining water supply of the basin to be developed, supplement the present supply, and relieve the ground water depletion in areas where use of this resource has developed beyond the dependable replenishment. Within the basin, 30,000,000 acre-feet of reservoir storage will be needed to supply an estimated total future mater requirement of about 20,000,000 acre-feet, Present use is almost 10,000,000 acre-feet. During the 1928-34 drought, there was an average annual deficiency in surface irrigat,ion n.ater of about 125,000 acre-feet. In addition, an overdraft of water in the upper San Joaquin Valley amounted t o an average deficiency of about 1,000,000 acre-feet a year. During the 7-year period (1928-34) t'he average annual outflow from the Central Valley Basin to t,lie ocean was 11,300,000 acre-feet. With the uses existing during that period, this amount was the residual from the natural supply within the basin. Of this total, about 1,900,000 acre-feet were included in outflows of equal to or less than those needed to protect the delta from salinity intrusions. Construction and coordinated operation of canals and reservoirs would have permit,ted utilization of most of the remaining 9,400,000 acre-feet of outflow, and would have enabled surplus waters t o be transported t o points of deficiency. Under future conditions, assuming completion of the presently proposed comprehensive Central Valley Plan, part of which is now constructed, and during a drought similar to fhe 1928-34 period, the usable total natural supply a t points of storage and diversion would be about 18,500,000 acre-feet, carry-over storage about 2,500,000, and importations around 500,000, thus making the total supply about 21,500,000 acre-feet. Use of 20,000,000 acrefeet plus evaporation losses of 1,500,000 acre-feet would be sustained. Additional importations from ot,her basins might, make further developments possible. Production of hydroelectric energy is an important element in developing the water resources of the Central Valley. The existing plants in the basin have a total installed capacity of almost 2,000,000 kilowatts. These power plants provide around 90% of all the electric energy used in the Central Valley and the adjoining coastal areas, including the San Francisco Bay area. Power requirements are growing rapidly in these areas. Forecasts of future power load growth show that all hydroelectric energy which can be made available from the planned multiplepurpose projects in the Central Valley will be needed t o meet the requirements estimat,ed for 1960.
Vol. 43, No. 12
COLORADO RIVER BASIN The Colorado River Basin totals some 242,000 square miles and hae many potentialities for further development and use of its resources. The mineral wealth of the basin is extensive; it contains, among other important supplies, generous quantities of uranium, considered of such vital importance to the national security. Agriculture, by necessity of climatic conditions, is almost entirely dependent on irrigation. Some 2,600,000 a(:res are still available for feasible irrigation development. Hon.cver, it is estimated that as much as 200,000 acres already irrigated will ultimately be a,handonpd unless new supplies of irrigation n-atc:~ are introduced. While the wat,er supply of the Colorado River is the subject of considerable study and debate, it can be pointed out that the Colorado River Compact' allocates to each of the upper and lon-rr basins in perpetuity a total of 7,500,000 acre-feet for beneficial consumptive use annually. This compact also provides that the lower basin may use an additional 1,000,000 acre-feet annually. The dividing point betn-een the upper and lower basins is 1,c.e Ferry, Ariz. Above this point lies the drainage area of the river in Wyoming, Colorado, and port'ions of SeJv Mexico, Utah, and Arizona. Belon- lies the drainage area in California, Xevada, and portions of Arizona, New Mexico, and Utah. The states above Lee Ferry have divided their apportionment by the Upper Colorado River Compact. States below Lee Ferry have yet t o apportion their ivater. In addition to these allocated URCS, t,he United States is obligated to deliver to Mexico 1,500,000 a c r e feet annually. Surplus waters, if any, in excess of that apportioned, are subject to definition in various nater law documents, and have yet to be divided. In addition to storage needed for Jyater development projects, the upper basin must provide in excess of 25,000,000 acre-feet of storage to ensure delivery obligations at, Lee Ferry. Unless such delivery is made, full use cannot be obtained from water allocated to the upper basin. Presently it is estimated that the upper basin is using around 2,500,000 acre-feet annually. Until reservoirs are provided for regulation of the river below most conservation project>s,future expansion is limited to a total use of a little more than 4,000,000 acre-feet annually. Future us(: of the 7,500,000 acre-feet must include evaporation losses 011 reservoirs. These losses will approach 1,000,000 acre-feet. In the lower basin, additional regulatory reservoirs and distribution syst,ems will be needed to develop all available water supplies. It has been estimated that about 5,000,000 acre-feet are presently being used in, and exported from, the lo\ver basin, The availability of abundant, low-cost electric power from these storage reservoirs would stimulate industry in the entire power market area and the extraction and processing of the basin's vast mineral reserves. Approximately 3!500,000 kilowatts of installed capacity remain available within the basin for such resource development and municipal use. An important specific example of potential industrial development in this area is the, production of oil from coal and oil shale. Although this industry js only just' emerging from the experimental stage, water is recognized as a major factor in many of the processes and the accompanying municipal expansion. UTILIZATION OF EXISTING SUPPLIES This discussion of important western rivers demonstrates that throughout the West the centers of demand for water are seldom located in areas of greatest availability. Surplus waters frequently flow to waste on one side of a divide while a shortage exists on the opposite side. Such conditions have caused numerous transmountain and transbasin diversions to be created. Perhaps the largest diversion is the transportation of water from the Colorado River Basin to the Missouri River Basin through the Alva B. rZdams Tunnel, a feature of the Colorado-Big Thompson
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December 1951
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Project in Colorado. This p m e t is alao of multiplepurpoee design t o provide supplemental irrigation water, and generate electrical power, besides providing for i n c d recreational w a n d benefits t o 6sh and wildlife propagation. The exportation of water from one basin to another has proved ita worth. The next step, which must be h k e n if the future needs of the growing population are to be met, will be the exchange of water through multiplebasins exportation systems. The diversion of water from one or several &ins with mrplua supplies t o others of deficient s ~ p p l yand high physical and eccnomic need are necessary before full utilization of water murces cart be effected. Another important phaee of the multiple-purpose concept i s the conservation and control of flood waters. These may range from the annusl flood flow to the great flood of infrequent occurrence. The benefits are manyfold; beaidee providing protection f& life and property from great floods such as those of 1948 in the Columbia River, 1950 in the Sacramento, and the recent 1951 di&er in the Kansas River Bsein, the increased reservoir storage e m against periods of shortages for industrial and agricultnral demands. The development of works to meet the menace of floodsia a vital and neoesssry element in the full develop ment of any existing water reeource. The dvage of water now lost to we through reduced quality, pollution, and nonbeneficial consumptive use could greatly supplement the intensive utilization deacribed above. Use of water for irrigated agrinilture d m not fully deplete the supplydocsted toit. Wlileamhtantialponion oftbrdjwrtad water ia lost though evaporation from water carried in C a d and lateral ditches and is consumed in crop growth, weed growth, and transpiration, some is returned to the stream. Portions of the water diverted for cropa are lost by seepage into the eoile, but returnagaiothrwghthegroundwatertablestothestream Bowat downstream pointa. Such return flows frequently are used t o aupplement n o m l supplies, but must be re-wed within the limitations of quality as reduced by the increased mineral content. The water quality thus induced by the soils through which they have moved may be a critical faetor in development of industrial, agricultural, or municipal growth downstream.
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five southweatern states-Arimna, California, New Mexico, Nevada, and Utah-phreatophytic plants comrnouly referred to as Water robbers” cover an area of some 4,700,000 acres and annually consume about 5,7w,oooacrefeet of water. Besides acting as water robbera, t h e e plants clog canal systems and impede the natural stream flow, as seen at the headwaters of lakes and reservoirs. ’ . Current investigations of them con’ .’’ ’ ditiona indimte that through judicious nes of herbicides such as 2,4D,phreatophytic plants euch 8 s salt cedars can be controlled and removed without damage to adjacent cash crops. Recent eradication operations have been conducted byaerial spraying in the Peoos and Rio G r a d e River Valleys in New Mexico with very gratifying results. It is also recOgniied that freeh water can be obtained from sea water by physical, chemical, and electrical methods. To date, the most effective method appears tq be by distillat,ion, uaing several stages of beat interchanges to reduce waste of heat. However, the coat for distillation alone is well above costs for distant diversions. CLOUD SEEDING In thepsat fcw yesrs tlirre has been iorlPasiog interest throughout the Wost in the posaibiliry 01 increasing pmipitatioo by cloud
seeding. In the temperate zones most precipitation falls from s u p e m l e d (water) clouds in the presence of ice crystals. Many supercooled clouds occur that do not yield precipitation bec~u8eof the absence of ice cmtals. Cloud seeders c k t o induce precipitation from some of these clouds by introducing dry ice or minute silver iodide nuclei. In any one instance, it is most di6icult t o determine whether artihial Beading caused, increased, or reduced subsequent rain or SMW. However, with access t o the recorda of d i n g operations and pmipitation, generally acceptable statistical evaluations of the effectivenew of the experiments undwbtedly will be made.
WLLUTION AND SALVAGE
BIBLIOGRAPHY
flow polluted by industrial wastes and the
senage ofpopulation centers must be treated to destroy or modify the bioloCjd, chemical, and mineral contamination. A recent survey by the Public Health Service shows that although all atrpams are not polluted, the masor ones am gravely atleoted,
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and the problem hss increased in national scope. The pollution fsctor already affects or eventually will affect all water reaourcea ddvehpment. State and federal legislation should npiscally spell out to industry and municipalities the minimum purity and quality standards for the water they r e h . The salvage of water lost t o nonbeneficial use has been the subject of intMsive study. Recent estimates indicate that in the
Bureau of Realamation. U. 8. Dent. Interior. “ColorsdoRiver.” (Much 1848). Ibid.. “Calumbia River.” (February1947). Ibid., “Central V d e y Basin” (Ausust 1949). Missouri Basin Interagency Committee. “Adequacy of Floss m the Missouri Rivsr“ (April 1951). U. 8.78th C o n m , 2nd Won,“Missouri River Basin.” 8 e ~ t e Daoument 191 ( A d 1944). Ibid (November 1944. Water Resouroaa Policy commission, “Water Policy for the American People;’ Vol. I, 11, 111 (December 195O-Janw 1961). ~~
R z c n r s ~ oAuguat 24. 1861.
