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Chapter 5. The Texas water system: implications for environmental assessment in planning for interbasin water transfers
Department of Geography
Indiana University, Bloomington, Indiana
THE DECADE of the 1960s was a time of enthusiastic proposals for large interbasin water transfer schemes. A new generation of plans was put forward in North America, headlined by the grandiose NAWAPA scheme and including numerous other proposals for transfers of unprecedented scale between basins in the northern and western parts of the continent (Biswas, 1978). Similarly, in the Soviet Union, existing plans were elaborated and ambitious new proposals were put forward for the transfer of water from the more humid to the less humid regions of the continent (Micklin, 1977; Soviet Geography, 1972). This spate of large interbasin transfer proposals arose from new realizations of engineering capability and economic growth in industrial economies. It had become technically possible to alter on a broad new scale those natural environments in which water is the limiting factor to continued growth.
The decade of the 1970s, however, was a period of retrenchment in planning for the large interbasin transfer schemes in North America. Some of the plans have been abandoned, many have been modified, and progress on all has been at least slowed down. Two factors are primarily responsible for the retrenchment: first, strong opposition has been raised by basins which would be called on to export their water resources, and second, rising costs have brought the economic feasibility of many large interbasin transfers into serious doubt.
A third factor which has also contributed to a more cautious approach is environmental considerations. The decade of the 1970s was a time when, according to White (1977): "Management of the world's water resources is undergoing a momentous shift. New approaches to complex river development are according greater recognition to its environmental limits and consequences." Recognition of these limits and consequences has been slower to affect large interbasin transfer plans, but it is gradually and fundamentally changing the approach to all water resources development. Furthermore, it will have increased importance in future planning and development because it is becoming more widely recognized that environmental systems and economic systems are intimately related, and that environmental systems provide the underpinnings for present and future economic systems.
Proposals for the Texas Water System give a clear illustration of this trend in planning for interbasin transfers. The original proposal of 1968, based on a large diversion from the Mississippi River into the state of Texas, has been modified considerably during the last decade. While the primary reasons for modification have been resistance from the areas of proposed water export and the increasing costs of construction, environmental considerations have also had a role. Indeed, the early planning for the Texas Water System serves now as a negative example of planning for large interbasin transfers. It illustrates the unbalanced approach of overwhelming attention being given to engineering and economic aspects of development with scant, perfunctory attention being given to environmental aspects. It provides a case study of the lessons learned in water resources development in the United States which other nations hopefully can learn without having to undergo the experience themselves.
THE TEXAS WATER SYSTEM
In 1968 the Texas Water Development Board put forward the Texas Water Plan to prepare for water requirements projected for the year 2020. The plan sought to meet water deficiencies in the state that would exist with projected population and economic levels after a fifty-year period of growth. A major element of the plan was the Texas Water System. This system envisaged interbasin transfers of two types: intrastate transfers from the humid eastern region of the state (about 1,200 mm average annual precipitation) to arid and semi-arid western regions (200 to 400 mm), and interstate transfers, specifically a large import from the Mississippi basin across the state of Louisiana to the east (see Figures 1 and 2).
The key to the Texas Water System is a series of reservoirs on the major rivers of east and central Texas which drain into the Gulf of Mexico. Ultimately the system of reservoirs, large and small, would be more than two hundred in number, with a combined storage capacity of 125x109 m³. Of this total, some 150 reservoirs existed or were under construction in 1968, with a combined storage capacity of about 63x 109 m³. The role of these reservoirs in the Texas Water System would be to store water, from the rivers of east Texas as well as from outof-state imports, prior to conveyance through two major canal systems: the Coastal Canal System and the Trans-Texas Canal System.
The Coastal Canal would extend approximately 600 km southwestward, flowing by gravity from the Sabine River on the eastern edge of Texas to the southern tip of the state. In addition to out-of-state water, this canal would transfer surpluses from the Neches, Trinity, and other basins of east Texas to more arid basins farther to the southwest. It would deliver 7x 109 m³ of water in the southern part of the state. Of this, 2. 2x 109 m³ would be used for irrigation in the Coastal Bend and Lower Rio Grande Valley agricultural regions, 1.7x109 m³ would be used for municipal/industrial supply, and 3.1x109 m³ would be released in coastal bays and estuaries to compensate for water impounded or used upstream that historically has fed these coastal areas.
The Trans-Texas Canal would extend about 1,200 km westward from the upper Sulpher River basin in northeast Texas. This canal would be concrete lined and would require a total lift by pumping of about 820 metres. It would deliver some 12.3x109 m³ annually to north and west Texas and to New Mexico. Of this amount, 11.1x 109 m³ would be used for irrigation, primarily in the High Plains, North-Central, and Trans-Pecos agricultural regions of Texas, but also including some 1.8x 109 m³ annually delivered for irrigation in New Mexico. From the newly constructed Cap Rock and Bull Lakes storage reservoirs in west Texas, water would be distributed as follows: 9.1x 109 m³ for irrigation on the High Plains, 1.8x109 m³ delivered to eastern New Mexico, 1.1X109 m³ for irrigation in the Trans-Pecos, and 618X106 m³ for municipal industrial use, including some 245 x 106 m³ conveyed by pipeline to the city of El Paso some 550 km south and west of the High Plains storage reservoirs. Other municipal/industrial deliveries of the system would include about 1.2x109 m³ annually for supply to the Dallas-Fort Worth area.
Figure 1. Rivers and Irrigation Areas in Texas
Figure 2. The Texas Water System.
Interstate transfer would provide a major share of the water conveyed westward, with the 1968 plan proposing that 15.4x 109 m³ be brought annually from the Mississippi River, which is some 300 km east of the Texas border. Two possible routes were suggested for this interstate conveyance in the preliminary phase of planning, one following the course of the Red River and entering Texas in the Cypress Creek basin, and the other involving a freshwater coastal channel that would deliver interstate water in the lower Sabine River.
The motivations for this system are important to trace briefly. Water supply had been recognized as a limiting factor to population and economic growth within Texas for several decades, and by the early 1960s the state had begun research on means to supplement the existing water resources. By the late 1960s the single most important impetus for water import schemes was the rescue of irrigated agricultural land in the High Plains region. Some sixty per cent of all water allotted for irrigation in the system would be delivered for irrigation on the High Plains, which has developed into one of the nation's leading areas for cotton, grain sorghum and other crops based on irrigation using pumped groundwater.
But use of the major aquifer for several decades has increased to the point where annual withdrawal of water (6 to 12x109 m³ annually in 1977) is vastly greater than annual recharge (less than 0.1x109 m³), and where recoverable groundwater storage has been reduced by half (to 164x109 m³) in the last decade. The maintenance of production in this agricultural region will not be possible a few decades in the future without new sources of water such as would be provided by the Texas water system.
Similarly, urban-industrial growth in centres like Dallas-Fort Worth, Houston, San Antonio, and other cities of the state will not maintain its present rate without additional water supplies. If the population of the state is to grow from about 11 million in 1970 to an estimated thirty million by 2020 (as projected in the plan) and if industrial production, petroleum production, and other economic activities are to keep pace, major new supplies of water will have to be provided.
The Texas Water System has not been implemented as a whole, although construction has proceeded on some features, such as individual storage reservoirs which could be part of the overall plan if it were to be implemented in its entirety. In 1969 a referendum to authorize funds to begin work on the plan was defeated, and in 1973 a reconnaissance investigation on the possibility of the interbasin transfer to west Texas and eastern New Mexico found that while the conveyance of more than 10 billion cubic metres of water from the Mississippi River system to the High Plains was practicable from an engineering point of view, it was not economically justifiable by current evaluation criteria.
A revised draft of the water plan, issued in 1977 and based on projected water supplies and needs in the year 2030, underlined the continuing effort to find imported water to meet the projected population and economic growth needs of the state. It forecast that a large area of the major aquifer underlying the High Plains region would be depleted by the year 2000. Concerning potential sources of imported water, it suggested that changing agricultural prices and production costs might make importing Mississippi water feasible, and it stated that other sources of imported water were being actually explored.
ENVIRONMENTAL IMPACT PLANNING
The wide range of potential environmental impacts in a large system of interbasin transfers such as those proposed in the Texas Water Plan are best discussed in terms of three groups: (a) those impacts anticipated in the exporting basins; (b) those anticipated along the routes of conveyance; and (c) those anticipated in the importing basins, or areas of delivery. This three-part breakdown provides the basis on which to discuss both the impacts of the Texas scheme and the role of environmental planning in the overall planning process.
The major kinds of impacts to be anticipated in the exporting basins include changes in the flow, sediment load, and channel configuration resulting from decreased discharge of the river. Additionally, the decrease of discharge has important implications for salinity conditions and the bioecology in the estuary and near-shore marine environments of a large river. The impact on related freshwater systems, such as lakes and canals, and their associated shoreline ecosystems is also to be carefully scrutinized. All these potential impacts are, of course, related to the schedule of diversion from the river-whether it is constant throughout the year, limited to high flow periods, or follows some other schedule. Certain factors must be considered here as well as throughout the transfer scheme, and these include water quality, conditions of micro-climate, and conditions of human health.
Regarding intrastate transfers from basins in eastern Texas, the primary environmental concern of the Texas Water Plan was the question of water quality. Problems were anticipated with the use of municipal return flow waters and the use of surface flows with high salinity for eventual export to west Texas. To meet these problems, quality control projects on municipal return flows and salinity reduction projects were reported; and the plan called for additional study in these areas and for methodologies for operational quality control of water deliveries with implementation of the plan. Reference was also made to problems of the quality of water imported to the system from the Mississippi or other out-of-state basins, although no detailed studies had been carried out.
The other environmental consideration given some attention in the original plan was the recreational and scientific significance of impacts on freshwater fish, waterfowl and other wildlife habitats which would be affected by reservoir development in the exporting basins of east Texas. Beyond this, however, none of the major changes in hydrobiology of these basins which could result from the proposed development was reported as having been studied.
Regarding the types and magnitude of impacts in the Mississippi basin resulting from the export of 1 5.4x 109 m³ of water annually, the plan reports no detailed study whatsoever. It is left to subsequent studies by agencies not affiliated with the Texas Water Development Board to study these impacts. Kazmann and Arguello (1973), for example, derived a minimum impact project for diversion of Mississippi water to west Texas and New Mexico which could divert at least 680 cubic metres per second (ems) when the discharge of the Mississippi at Vicksburg is more than 10,188 ems. Such a diversion could normally be continued during 8 months annually, and they concluded that it would not alter the movement of salt water in the channel of the Mississippi significantly from conditions existing in 1972.
Problems of the river's sediment load would be difficult to handle, however. Since water for conveyance to Texas would have to be relatively free of sediment, diversion at a higher rate and for a shorter period during the year than is compatible with the minimum impact project would be required. Further complications to implementing the minimum impact would arise with improvement of the Mississippi navigation channel, which would increase the likelihood of upstream movement of the salt water wedge, and with future development for irrigation, water supply and recreation in the Mississippi system. If such development resulted in reduced peak flows and shorter periods of high discharge, the effect would be to require a higher diversion rate for conveyance to Texas during a shorter period each year. If the pumping period were in the order of seven months per year, rather than the optimum eleven months, the greater pumping and storage capacities required for the intrastate transfer would raise the cost of the project considerably (Price, 1971).
Other potential impacts for which studies were undertaken by the Mississippi River Commission and the Louisiana Department of Public Works involve the bays and estuaries of the Mississippi Coast (Watts, 1970). Detailed studies had not been done previously on what impacts would result in the coastal area from decreased flows of the Mississippi River. The decreasing inflow of fresh water to the bays and estuaries along the Gulf Coast, which was apparent by the early 1970s without any major export of Mississippi basin water, have far-reaching implications for that area. Even if municipal, industrial and agricultural needs could be supplied after diversion to Texas, the vitality of the commercial seafood industry and saltwater sports fisheries must also be considered (Price, 1971).
Incorporation of these environmental considerations in the 1977 revised draft of the Texas Water Plan remained surprisingly small. In that draft the major new environmental discussion concerned aesthetic consideration of landscape disturbance caused by development, in reaction to controversy then current over wild and scenic waterway preservation. But the weight of this and the more basic potential environmental impacts remain very much secondary to the plan's main consideration of engineering and economic feasibility.
In fact, the 1977 revised draft plan acknowledged that importing water from the Mississippi may not be feasible and reported that other smaller rivers, mainly tributaries in the Missouri River basin, were being studied as possible sources of interstate transfers. This adaptation is not a reaction to environmental considerations, however, but to the federal government's 1973 study which found that importing Mississippi water was not economically feasible.
Routes of Conveyance
Concerning the routes of conveyance in an interbasin transfer, the most important potential impacts are those affecting ground and surface water systems along the route. Seepage from transfer canals can have major impacts on contiguous and nearby ground and surface waters, and intersection of the surface drainage patterns may present potential problems. Questions of water quality, health and effect on climate must also be considered.
In the 1968 Texas Water Plan the question of water quality in the TransTexas Canal System and the Coastal Canal System received some attention. The need for quality control projects on municipal return flows and salinity reduction projects, of the kind proposed for east Texas exporting basins, were also recognized as necessary in some areas of the conveyance systems. Other kinds of potential impacts were not discussed, although many would be avoided by construction of the Trans-Texas Canal as originally proposed. It was to be a lined canal that followed watershed divides for the most part. As such it could have minimal impact on local ground and surface water systems, including problems associated with crossing local drainage systems. The same could not be anticipated, however, for the Coastal Canal System, which would intersect numerous streams draining into the Gulf of Mexico.
No attention is given in the original plan to the potential problem of thermal pollution along the Trans-Texas Canal, which would arise from generation of the power necessary to pump water in the canal. The amount of power required was equal to one third of the total generation capacity in the state of Texas when the plan was put forward. Nor were potential effects on micro-climate or the dispersal of harmful organisms along the canal discussed. Some critics of the plan speculated on the implications of the water moccasin, a poisonous snake common in the exporting regions, being dispersed throughout the state by the transfer scheme. The revised draft plan of 1977 stated that studies were continuing to identify low impact corridors for transfer routes to make the plan more feasible, but it does not indicate to what degree the concern is for environmental feasibility as opposed to the basic concern with economic feasibility.
Areas of Delivery
In areas of delivery the potential impact on ground and surface water systems must be carefully scrutinized. Problems of salinity in agricultural areas receiving additional irrigation water are potentially the most troublesome, but other effects associated with water table changes and with existing surface water bodies-for both agricultural and municipal/industrial deliveries-are potentially problematic. As in other regions of the proposed transfer, questions of water quality, health and climatic change must be considered as well.
Considerable attention is given, both in the original and in the revised draft versions of the Texas Water Plan, to the bays and estuaries along the Texas Gulf Coast. One of the primary benefits of the Coastal Canal System envisaged by the Texas Water Development Board is the provision of supplemental inflows of fresh water to protect these coastal water systems. With population concentration greater near the coast, and with increasing water use from the various rivers that drain the state in a general northwest to southeast direction, the freshwater flow into bays and estuaries is projected to decrease, in some cases to less than one-half the historical average flow, by the year 2020. Although the release of water into these bays projected by the Texas Water Plan would not make up all the difference of decreased flow, it would be intended to help maintain the productivity of these waters. The revised draft plan further addresses this problem by suggesting the use of various inflow models for hydrodynamic, transport, flood routing, marsh and estuarine systems. And the concept of sustaining annual river inflows is adopted to arrive at the quantities of water necessary for maintaining primary ecosystem habitats and sustaining estuarine productivity.
Much less attention is given in the plan to environmental impacts in irrigated areas receiving imported water. Very brief reference is made to salinity problems that might arise in using imported water in the major High Plains irrigation area in the 1968 plan and the 1977 revised draft indicates that some additional studies were being carried out. The potential impact on groundwater systems in other irrigation areas designated to benefit from the import scheme and on both ground and surface water systems in the municipal areas that would receive water is not discussed, however. One environmental consideration which is recognized as a problem in the plan is the concentration of encephalitis-carrying mosquitoes in certain areas of west Texas which could be made more serious with the delivery of large amounts of water.
IMPLICATIONS OF ENVIRONMENTAL PLANNING
Four main problems of planning for environmental effects emerge in this review of the Texas Water Plan. They are characteristic of the planning process that was current in the 1960s, when large interbasin projects were so enthusiastically proposed; and they are precisely the problems for which solutions have begun to emerge during the 1970s. Continued planning for schemes to import water into Texas has been forced to recognize the necessity of solutions.
The four problems are: (1) lack of thorough study of environmental factors; (2) lack of co-ordination between studies on environmental and other aspects of development; (3) use of a three-step planning process which subordinates environmental feasibility to engineering and economic feasibility; and (4) the unbalanced approach which results from these three problems.
The lack of thorough study of environmental factors and the lack of coordination with other aspects of planning are apparent from the discussion of the Texas Water Plan above. The three-step planning process also is clear from this review-the first step is the plan being put forward with primary attention to economic and engineering feasibility and with relatively little attention to the potential environmental impacts. The second step is studies of some potential environmental impacts undertaken in reaction to the initial plan, rather than in coordination with it. And the third step is revisions in the plan to accommodate some environmental issues perceived more as political obstacles to the plan's adoption than as necessary adaptations to the geographic realities in which development is to be carried out.
The imbalances inherent in this approach were widely accepted through the 1960s, and they were of two types: unbalanced emphasis on some considerations at the expense of others, and unbalanced emphasis on certain regions at the expense of others. Focus on environmental systems was the modus operandi of development construction, as was unequal concern for one region at the expense of another. It was acceptable, for example, that projections of primary and secondary economic benefits should be carried out without even basic examination of primary environmental impacts, or that a plan might be put forward based on detailed projections for growth in Texas over a fifty-year period without comparable projections for an exporting region, such as the Mississippi basin.
But the problems engendered by this unbalanced approach became too large and too pervasive to ignore. The shift to greater recognition of environmental limits and consequences has been based on wider acceptance of the two facts mentioned at the beginning of this paper: environmental systems and economic systems are intimately related, and environmental systems provide the underpinning for present and future economic systems. A proposed interbasin transfer cannot be called beneficial to an importing basin until the potential environmental impacts are evaluated; and a potential exporting basin cannot be declared to have a water surplus until all facts of its environmental and economic systems have been studied in the same detail as have those of the potential importing basin.
The decade of the 1970s has seen efforts to reshape the process of planning for water resources development. Interdisciplinary approaches are now taken as a sine qua non for planning. The use of environmental impact assessment, and specific planning methodologies, such as the Iterative Open Planning Process (IOPP) (see Ortolano, 1978) are evolving to redress the imbalances that have existed in the past. The implications of this experience for developing countries, and specifically for the case of China's proposed northward transfer of Chang Jiang waters, are immense. Ideally, the lessons of the unbalanced approach to water resources development planning can be learned without the phase having to be experienced by China herself.
The similarities and the differences between the Texas system and the proposed Chang Jiang transfer scheme provide perspective on what the potential environmental impacts might be. The two projects involve a similar scale of transfer-10x 109 m³ conveyed annually over distances of 600 to 1,200 km in the Texas case, and about 15 X 109 m³ conveyed some 800 km in the Chinese proposal. General environmental parameters are comparable, in that the water from the humid basin of the largest river of each continent would be diverted to semiarid plains regions, to be used primarily for irrigation and secondarily for municipal and industrial water supply. While the provision of irrigation water in both schemes is intended to meet the needs of future agricultural growth, there is, however, a greater element of urgency motivating proposals in the Texas case. Urgency may also be felt by some for implementation of the Chang Jiang transfer, yet the element of rescuing an agricultural system which presently is based on the mining of fossil groundwater is not the same.
Beyond this, certain geographic and engineering features of the two schemes are significantly different, most notably the amount of storage capacity and pumping required for part of the Texas system, the chain of large freshwater lakes along the proposed eastern route of the Chang Jiang transfer, and the plans for unlined canals in the Chinese case.
Two other factors underscore the importance of careful environmental evaluation for the Chang Jiang transfer. Firstly, since population density and intensity of agricultural land use are much greater in the Chang Jiang basin, along the potential transfer routes, and in the North China delivery region than in the counterpart regions of the Texas Water System, comparable environmental impacts could have much greater repercussions on society and economy in China than in the US example. Secondly, since the area of the Chang Jiang transfer is a much more fundamental part of the agricultural and industrial fabric of the national economy than is the case with the proposed Texas Transfer, any effects of the transfer would be magnified in a comparative sense: a successful transfer would contribute much more to national development, and an unsuccessful transfer would be far more detrimental.
Most important is the fundamental lesson of the Texas Water Plan-the need for balanced planning of the proposed transfer scheme. Planners must ask themselves if environmental systems are being studied with the same detail as are economic and engineering systems, if all relevant studies are well co-ordinated, and if balanced emphasis is being given to all aspects of potential development. Planning must be based on projected population, economic levels, and water needs at thirty, forty, or fifty years in the future for an undertaking of this magnitude. If such considerations are not taken into account, then the lessons that have been learned in the United States and elsewhere over the last decade will be needlessly repeated.
Biswas, A. K., 1978, "North American Water Transfers: An Overview", Water Supply and Management, Vol. 2, pp. 79-90.
Kazman, R. G. and Arguello, O., 1973, The Mississippi River-A Water Resource for Texas? Lousiana Water Resources Research Institute, Bulletin 9, Lousiana State University.
Micklin, P.P., 1977, "NAWAPA and Two Siberian Water-Diversion Proposals: A Geographical Comparison and Appraisal", Soviet Geography: Review and Translation, Vol. 18, No. 2, pp. 81-99.
Ortolano, L., 1978, "Environmental Assessments in Water Resources Planning", Water Supply and Management, Vol. 2, pp. 159-176.
Price, B. R., 1971, "Possible Diversion of Mississippi River Water to Texas and New Mexico", Water Resources Bulletin, Vol. 7, No. 4,
Soviet Geography: Review and Translation, Vol 8, (Nov., 1972). This entire number is devoted to articles on specific problems of the proposed transfers.
Texas Water Development Board, 1968, The Texas Water Plan, Austin, Texas.
Texas Water Development Board, 1977, Continuing Water Resources Planning and Development for Texas (Draft).
Watts, C. T., 1970, Paper at joint discussion on "Export of Mississippi River Water to Texas and New Mexico", Journal of the American Water Works Association, Vol. 62, No. 61: 367-375.
White, G., 1977, "Comparative Analysis of Complex River Development". In Environmental Effects of Complex River Development, Gilbert White (Editor), West view Press, Boulder, Colorado.
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