5
Economic, Legal, and Institutional Considerations

Decision making by public and private entities about water resources cannot be understood without consideration of the relevant institutional factors. Indeed, many water resource professionals would agree that "institutional problems in water resources development and management are more prominent, persistent, and perplexing than technical, physical, or even economic problems..." (Ingram et al., 1984). Because ground water recharge projects are still somewhat novel, these factors are less obvious, than, for example, the familiar dynamics that led to western dams and irrigation projects. This chapter examines the economics, regulatory schemes, and key actors that affect ground water recharge projects.

ECONOMIC ISSUES

The scarcity of high-quality water supplies is intensifying in many regions of the United States. Environmental and fiscal problems constrain the construction of new surface water storage facilities. In many regions, declining water quality threatens potable supplies as well as potential sources of new supply. The constraints on the development of additional supplies have become more stringent at the same time that demands for additional municipal and industrial water are growing.

Simultaneously, water quality laws, policies, and regulations have forced municipalities to subject wastewater to increasingly more expensive treatment processes prior to discharge to surface waters. Because of this required treatment, the quality of many treated municipal wastewaters is sufficiently high that with relatively modest additional treatment they can be recycled and made avail-



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Ground Water Recharge Using Waters of Impaired Quality 5 Economic, Legal, and Institutional Considerations Decision making by public and private entities about water resources cannot be understood without consideration of the relevant institutional factors. Indeed, many water resource professionals would agree that "institutional problems in water resources development and management are more prominent, persistent, and perplexing than technical, physical, or even economic problems..." (Ingram et al., 1984). Because ground water recharge projects are still somewhat novel, these factors are less obvious, than, for example, the familiar dynamics that led to western dams and irrigation projects. This chapter examines the economics, regulatory schemes, and key actors that affect ground water recharge projects. ECONOMIC ISSUES The scarcity of high-quality water supplies is intensifying in many regions of the United States. Environmental and fiscal problems constrain the construction of new surface water storage facilities. In many regions, declining water quality threatens potable supplies as well as potential sources of new supply. The constraints on the development of additional supplies have become more stringent at the same time that demands for additional municipal and industrial water are growing. Simultaneously, water quality laws, policies, and regulations have forced municipalities to subject wastewater to increasingly more expensive treatment processes prior to discharge to surface waters. Because of this required treatment, the quality of many treated municipal wastewaters is sufficiently high that with relatively modest additional treatment they can be recycled and made avail-

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Ground Water Recharge Using Waters of Impaired Quality able for a variety of uses. The economic attractiveness of treated municipal wastewater as a source of supply has focused increasing attention on the possibility of using it to recharge aquifers. Historically, treated wastewater has been used on a modest scale both to augment ground water supplies and as a means of protecting aquifers in coastal regions from seawater intrusion. The Economics of Ground Water Use There is a substantial and varied literature on the economics of ground water use (see, for example, Burt, 1970; Cummings, 1970; Gisser, 1983; Bumess and Martin, 1988; Provencher and Burt, 1993). A number of common principles related to the use and management of ground water are developed and characterized in this literature. For example, ground water is most efficiently used when it is extracted at rates such that the net benefits (total benefits net of total costs) from use are maximized over time. The benefits are typically determined by the use to which the water is put. In the short term, costs include the cost of extracting ground water and the opportunity, or user, cost. The cost of extracting ground water is usually a function of energy cost, pump efficiency, and the depth from which the water must be pumped. Extraction cost increases as energy cost and pumping depth increase, and it declines as pump efficiency increases. The opportunity cost of extraction is the cost of extracting the water now rather than leaving it for later use. The opportunity cost, which is frequently called a user cost, captures the fact that water pumped in the current period results in a lowered ground water table for all future periods if pumping rates exceed safe yields of the aquifer. The incremental cost of pumping from a lowered water table in the future must be accounted for if current extractions are to be economically efficient. Much of the economic literature on ground water resources focuses on the fact that where ground water is treated as a common property resource, extractions tend to occur at rates that are inefficient. When pumpers fail to account for all of the costs of extraction, including the user cost, the rates of extraction are greater than the economically efficient rate. In the long run, the rates of extraction for any given aquifer cannot exceed the rate at which the aquifer is recharged—the safe yield—without overdrafting the aquifer. Overdrafting can brings costs: land subsidence, greater risk of flooding, greater risk of salt water intrusion in coastal areas, and the increased costs of reaching and pumping the water from the lowered water table. When over-drafting is persistent, the ground water table is progressively lowered until a point is reached at which the cost of extracting the ground water from any lower depth is greater than the benefits that could be obtained from any of the uses to which that water might be put. At this point, it is no longer economical to continue pumping and further declines in the ground water table are arrested. Ultimately, proper management of the relative magnitudes of the pumping cost

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Ground Water Recharge Using Waters of Impaired Quality and the benefits from use can ensure that only the annual recharge is extracted; when this balance is reached, the aquifer is said to be in steady state. There can be circumstances, however, in which overdrafting is economically efficient. For instance, when the benefits of use are quite high in relation to the costs of extraction, overdrafting may be justified. It is important to remember, however, that overdrafting ultimately is self-terminating. Another consideration relates to the optimal water table depth at which steady state is reached. The optimal steady-state depth will be attained if all costs of extraction, including the user cost, are accounted for by pumpers. Where. ground water is treated as a common property resource, pumpers have an incentive to ignore the user cost, and this results in a deeper than optimal steady state depth. In this instance, rates of extraction leading to the steady-state are greater than the economically optimal rate, and pumping depths are lower overall than the optimal pumping depth. The principal lesson from the basic economics of ground water use is that where ground water is exploited in an individualistically competitive fashion, the rates of extraction and the steady state depth tend not to be economically optimal. The rule of capture prevails, and this means that pumpers only obtain the right to use ground water once they have pumped it and are prepared to put it to use. The user cost tends to be ignored, both because purepets believe that their own extractions will have an infinitesimally small impact on other pumpers and because they perceive that voluntary restraints on extractions serve only to make the water available to potentially competing pumpers. Corrective measures that have been identified include pumping quotas, pump taxes equivalent to the marginal user cost, and the formal vesting of property rights to ground water in situ. Understanding of the economics of ground water use leads to the conclusion that ground water will not be used in an economically efficient fashion when it is treated as a common property resource. A single pumper will usually account for the consequences of today's extractions on tomorrow's extraction costs. The problem will arise where there are many pumpers behaving competitively. To address it, some form of management will be required. This lesson has important implications for the artificial recharge of ground water. If ground water is treated as a common property resource, the incentive to incur the expenses associated with artificial recharge will be eroded because the additional water will be available for capture by other pumpers, who presumably are not obligated to help pay for the recharge operation. Thus, in situations where there are many competing pumpers and no regulation of extractions, the returns from artificial recharge operations cannot be fully captured by those who plan and finance the operations. Artificial recharge of ground water can have at least two distinct purposes. First, the recharge water can be extracted and put to direct use. Second, in situations where an aquifer may be threatened by seawater intrusion or intrusion

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Ground Water Recharge Using Waters of Impaired Quality of very low quality ground water, artificial recharge can be used to protect the entire aquifer. The economics of artificial recharge for direct use has been analyzed in some detail by Brown and Deacon (1972), Cummings (1971), and Vaux (1985). Artificial recharge augments the rate of recharge and thus increases quantifies of water that can be optimally extracted at any point in time. Moreover, artificial recharge results in an optimal steady state pumping depth that is shallower than the optimal depth that would have prevailed in the absence of artificial recharge. Finally, artificial recharge can ameliorate problems of uncertainty that arise from the inherent variability of runoff and surface supplies that contribute to or are available for ground water recharge. These conclusions require, of course, that the incremental costs of the artificial recharge water be less than or equal to the incremental benefits that accrue from the uses to which the water is ultimately put. The economics of recharge in the second case, where recharge is used to prevent saltwater intrusion or otherwise protect an aquifer, has been treated in a number of case studies (Cummings, 1971; Warren et al., 1975). In these instances, the benefits that accrue are equivalent to the net benefits from the protected aquifer that would be lost if saltwater intrusion remained unabated. An economically efficient recharge operation requires that the incremental costs of recharge be less than or equal to the net benefits protected. If the aquifer to be protected is exploited competitively without pumping restrictions, the net benefits of protection would be less than they would be if extractions were economically optimal. The Economics of Artificial Ground Water Recharge with Treated Municipal Wastewater The economic feasibility of ground water recharge with treated municipal wastewater will vary from situation to situation. Recharge is but one option for managing water supply and the disposal of wastewater. The economic feasibility of recharge with treated wastewater will depend critically on the costs of other options for augmenting water supplies, the costs of alternative means for disposing of wastewater, and the benefits or returns that accrue from the availability of additional water supplies and the effective management of wastewater. Thus, in every situation economic feasibility must be assessed within the context of the particular water supply and demand situation and with specific reference to the array of alternatives that may be available to solve the water management problems in question. Demand The benefits of additional water supplies are normally measured by the willingness of consumers to pay or by the demand for additional water supplies.

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Ground Water Recharge Using Waters of Impaired Quality Generally, the willingness to pay for additional municipal and industrial supplies is expected to grow as urban population and economic activity increase. This is particularly true in the arid and semiarid western states, where nearly all of the economic and population growth is occurring in urban areas, but it is also clearly apparent in other water-short areas such as Florida. If the willingness to pay for recharged wastewater exceeds the cost of supplying that water and there are no cheaper alternative sources, recharge with wastewater may be an attractive option. Even where water quality and other factors are roughly comparable between ground water and alternative sources of surface water, there is at least one reason why the willingness to pay to acquire rights to ground water resources may be higher than for rights to surface water. In many areas, high quality ground water may be economically more attractive than alternative sources of surface water because it is reliably available. In the short run, the availability of ground water is not normally dependent on precipitation in the same way the surface water availability is. Thus, ground water tends to be relatively insulated from the effects of drought and, other things being equal, the willingness to pay for reliable ground water may be higher than for a source subject to interruption. The willingness to pay for reliable ground water sources can be diminished, however, if the quality of the ground water in question is distinctly lower than the quality of comparable surface water supplies or if the risks and uncertainties of adverse effects on human or environmental health associated with recharged ground water supplies are significantly higher than those associated with comparable surface water supplies. The Cost of Water Supplies The attractiveness of treated wastewater as a source of ground water recharge depends crucially on how the cost compares to the cost of alternative sources of supply. There are several reasons for believing that treated wastewaters may enjoy considerable cost advantages over other sources in the immediate future. In most regions of the country, the cost of developing new surface supplies has become prohibitive. Over the last several decades, the cost of constructing civil works has risen faster than the rate of inflation. Moreover, nearly all of the easily developed surface water storage sites have already been developed, leaving only sites that are costlier to develop or quite remote. In many instances, the combination of these two factors alone means that the cost of new surface water storage facilities outstrips the willingness to pay for new supplies. In addition, the willingness to subsidize the cost of new water supply facilities from public revenues has declined dramatically from the dam-building heyday of the 1950s and 1960s and before. To these financial constraints, the environmental cost of surface water de-

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Ground Water Recharge Using Waters of Impaired Quality velopment must be added. It is now recognized that surface water impoundment facilities can cause significant environmental damage. Strong public preferences for environmental amenities, together with the substantial cost of mitigating or compensating for environmental damage, have helped to make the construction of new surface water storage facilities far less attractive than it once was. Concerns about adverse environmental impacts lead to strong political opposition to the development of additional impoundment facilities. Even in the relatively rare instances in which the cost of new facilities is consistent with the willingness to pay, the potential adverse environmental impacts create strong political resistance to the development of such new facilities. The result is that new surface water storage and conveyance facilities have become a relatively unattractive and, in some instances, unacceptable means of developing new water supplies. On the other hand, many aquifers contain unused storage capacity, which can be developed at relatively modest cost and without the adverse environmental consequences frequently associated with surface storage. Because ground water storage avoids many of the high costs associated with surface storage, conjunctive use—the integrated management of ground and surface water—has become an increasingly attractive option for augmenting developed water supplies. Conjunctive use schemes often prove infeasible, however, because of the absence of ''surplus" surface water that could be stored in the ground. Many western streams are already fully allocated, and the increasing contentiousness of reallocation proposals in a number of middle western and eastern streams suggests that streams in those regions may be fully subscribed de facto. The resultant scarcity of surface waters available for development means that the search for additional water supplies has turned to more exotic sources, including the desalinization of brackish waters and seawater. It is true that changes in water allocation institutions, including, for example, more widespread adoption of water markets, may help ameliorate the scarcity of water, particularly in the West. Nevertheless, where new supplies are sought, the costs of treated waste-water may compare favorably with the cost of water from alternative sources because state and federal regulations require extensive treatment of wastewater irrespective of whether and how it is to be reused. The incremental costs of rendering treated wastewater suitable for nonpotable and even potable uses may thus be quite modest in many cases. The incremental costs of upgrading the quality of treated wastewater will vary widely from situation to situation and depend on a number of variables. The cost of land acquisition for the siting of treatment plants and spreading grounds and the cost of constructing injection wells will vary from project to project and can be significant. Similarly, the need to transport treated wastewater from the place of treatment to the site where it is to be spread or injected may add substantial cost (Vaux, 1985). In many instances, however, the most impor-

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Ground Water Recharge Using Waters of Impaired Quality tant determinant of economic feasibility will be the cost of the additional treatment required to improve the quality of the wastewater to the desired level. Data recently developed by the Orange County Water District (Orange County Water District/County Sanitation Districts of Orange County, 1993) for three different treatment options are illustrative. Table 5.1 presents the quality parameters of the product waters associated with the three treatment options and the costs of those options. The three options entail differences only in the levels of reverse osmosis and microfiltration applied to the product water. For options 1 and 2, it is assumed that only partial microfiltration is provided, with option 2 requiring it to a greater degree than option 1. Option 3 entails full microfiltration. The major quality difference is in the total organic carbon (TOC) reduction. The data illustrate the sensitivity of wastewater reclamation cost to the level of quality desired. The cost is, of course, also quite sensitive to the difference between the quality of the source water and the desired quality of the product water. Thus, the magnitude of the cost will be crucially conditioned by regulatory requirements on the quality of waters to be reclaimed by spreading or direct injection. In the Orange County situation the least-cost alternative source of water is surface water delivered from the Metropolitan Water District at a cost of $600 per acre-foot. To this must be added the capital and operating costs of transport TABLE 5.1 Comparison of Treatment Costs and Product Water Quality, Well Injection at Orange County, California Chemical Constituent Option 1 Option 2a Option 3a Total dissolved solidsb 650 mg/l 600 mg/l 600 mg/l Sodium 143 mg/l 139 mg/l 139 mg/l Chloride 151 mg/l 140 mg/l 140 mg/l Sulfate 140 mg/l 122 mg/l 122 mg/l Total organic carbon 8.6 m/l 5.5 mg/l 5.5 mg/l Cost per acre-footc $251 $359 $387 a The cost difference between options 2 and 3 is attributable to employment of full microfiltration for option 3 but only partial microfiltration for option 2. b Source water is assumed to contain 900 mg/l total dissolved solids for all three options. c Cost includes capital consumption, debt service, and operation and maintenance costs. Source: Orange County Water District/County Sanitation Districts of Orange County, 1993.

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Ground Water Recharge Using Waters of Impaired Quality ing the water to spreading grounds, which are $82.40 per acre foot. The total costs of the least cost alternative, then, is $682.40. Thus, option 1 is the least-cost alternative, but both options 2 and 3 are less costly than purchasing supplemental surface water supplies (Orange County Water District/County Sanitation Districts of Orange County, 1993). It is important to note that wastewater treatment facilities generally exhibit increasing returns to scale. Thus the costs of operation are usually cited for some constant and optimal quantity of water to be treated, given the size of the treatment facility in question. If the volumes of wastewater to be treated are highly variable from season-to-season or year-to-year, the costs of treatment may be higher since the facilities cannot be operated consistently at optimal levels. Similarly, if the volumes of wastewater to be treated decline over time because of water conservation efforts, the costs of wastewater treatment could increase as the volumes of water to be treated no longer match well with the size or scale of the treatment facility. These points underscore the importance of accounting for likely changes in future volumes of wastewater and the constancy of those volumes in the design of wastewater treatment facilities. Inasmuch as the costs and benefits of using reclaimed wastewater vary from situation to situation, it is difficult to generalize meaningfully about the economic attractiveness of reclaimed wastewater. It is clear, however, that the feasibility of artificial recharge requires the existence of unambiguous fights to the reclaimed water once it is in the ground. Beyond this, the specific economic calculus depends on the cost of the particular treatment and spreading or reinjection scheme as well as the cost of alternative sources of supply. LEGAL ISSUES Artificial recharge of ground water is one of the developments in water management that is challenging existing legal strictures to respond to changing societal needs. Experience with recharge projects suggests that society's laws can evolve to accommodate new strategies such as artificial recharge, if demand is strong enough. One difficult question raised by ground water recharge is, What policies should be formulated to protect public health, safety, property, third-party, and ecological interests, while not imposing inappropriate controls on this form of water development? The decentralized nature of the current regulatory structure will, in time, provide experience that demonstrates the merits of different regulatory standards. For now, some of the regulations that have been applied by different government entities can be surveyed and guidance sought from these policies. The controls imposed vary greatly from jurisdiction to jurisdiction, so what follows is a conceptual guide to the sort of considerations that have been raised in different areas. California has the most extensive regulatory scheme

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Ground Water Recharge Using Waters of Impaired Quality for ground water recharge, and these regulations and their institutional setting axe illustrative. This study is focused on the artificial recharge of ground water for subsequent reuse of water, whether for potable or nonpotable uses. The legal issues are grouped under the general topics of water rights, protection of ground water quality, use of the recharge water after recovery, and environmental consequences. General statutes that might have a bearing on projects are also reviewed. Considerations that are unique to the source of the recharge water (e.g., treated municipal wastewater, stormwater runoff, and irrigation return flow) are addressed when possible. Water Rights A prime issue in ground water recharge is the ownership of the water proposed for recharge. A project proponent must have the legal right to use the source water for that purpose. As a corollary, the project proponent must have the legal right, against other competing users, to withdraw the recharge water. A water right is commonly established for some use, such as irrigation, industrial processing, or domestic water supply. When the source of ground water recharge is water that has previously been used in some fashion, the question presented is whether the entitlement to use it also creates a right to control what is left over. For example, domestic wastewater can be viewed as a liability that a city must dispose of, or as an asset that might be of value to someone. In the arid West, the only flow in a stream may come from wastewater produced and discharged by a city. Downstream users may become dependent on this flow, and ecosystems may emerge that rely on it. Someone proposing to use this "resource" for a new purpose, such as ground water recharge, must have a legal entitlement to use the water in that way. The ownership of wastewater was at issue in Arizona Public Service Co. v. Long, 160 Ariz. 429, 773 P.2d 988 (1989). In this case, a municipal government was challenged on its ability to sell effluent that it had formerly disposed of in a stream. The court held that the effluent could be sold by the city and that the city was not required to continue the discharge. The water was neither "surface water" nor "ground water," although the legislature could in the future bring it within its statutory scheme for these waters (McGinnis, 1990). The New Mexico Supreme Court in Reynolds v. City of Roswell, 99 N.M. 84, 654 P.2d 537 (1982), also permitted a discharger to cease discharging effluent to a stream, despite the objections of the state engineer. New Mexico, in fact, has a statute defining effluent as "private waters" and allowing the discharger to reuse it (N.M. Star. Ann. § 72-5-27). The California legislature established a statutory right to reclaimed waste-water in the entity that operates a wastewater treatment facility (Cal. Water Code § 1210). The statute establishes rights in the wastewater with respect to the

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Ground Water Recharge Using Waters of Impaired Quality supplier of the water. With respect to downstream entities that have legal interests in flows, however, permission of the water board must be obtained before the discharge is affected (Cal. Water Code § 1211). The existence of a right to reuse water may also be dependent on the nature of the original entitlement to water. A user's water right may have been calculated assuming that a certain volume of water would be returned to the stream, so that the user would not have the right to instead divert that water. In some instances, a user's entitlement to reuse water will be a matter of contractual arrangements with the supplier. Finally, in some states an additional element of ownership may be required before a project can proceed. Under the prior appropriation doctrine, a use must be permissible, or "beneficial," under state law for an applicant to have fights to the water. Colorado, Idaho, Kansas, Nebraska, Oklahoma, and Oregon have recognized ground water recharge in their water laws in varying manners (Colo. Rev. Star. § 37-92-103(10.5) (1992); Idaho Code § 42-4201A(a)(2) (1992); Kan. Star. Ann. § 82a-928 (1992); Neb. Rev. Stat. § 46-295 (1992); Okla. Stat. Title 82, § 1020.1-1020.22 (1992); Or. Rev. Stat. § 537.135 (1991)). Florida takes an inventive approach to linking water rights to reuse of reclaimed wastewater, including reuse through recharge of ground water. Regulations of the Environmental Regulation Commission provide that "In implementing consumptive use permitting, a reasonable amount of reuse of reclaimed water from domestic wastewater treatment facilities shall be required within designated water resource caution areas, considering economic, environmental, and technical factors" (Florida Administrative Code A.R. 17-40.416(2)). Environmental statutes also may affect a user's fight to cease making a discharge to a stream or wetland for the purpose of ground water recharge. A new diversion could, for example, affect an endangered species (Western States Water Council, 1990), but aside from protections offered endangered species there would generally be no protection for the affected environment. Oregon is an exception to this general rule: it has provided by statute that a ground water recharge permit shall not be issued "unless the supplying stream has a minimum perennial stream flow established for the protection of aquatic and fish life" (Or. Rev. Stat. § 537.135 (1991)). An environmental review, if required under state or federal law, might identify the environmental interest in maintaining a discharge. Interestingly, California has acted to protect two environmental opportunities that can be created by water reuse: if water reuse lessens stream demand, the remaining flow in the stream can be protected from new appropriations, and if reclaimed water is discharged to a stream, the newly created streamflow can be protected (Cal. Water Code § 1212). Water fights are also of key importance when the time comes to withdraw water from a ground water basin. Without clear protection of the project proponent's economic investment in the recharge water, there is no incentive for projects. A study by the Western States Water Council identified only a few

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Ground Water Recharge Using Waters of Impaired Quality western states that explicitly protect rights in recharge water (Western States Water Council, 1990). In California, case law has established the nature of the recharger's right to exclusive withdrawal of the recharged ground water (Los Angeles v. San Fernando, 14 Cal. 3d 199, 537 P.2d 1250 (1975) and Alameda County Water District v. Niles Sand and Gravel Co., 37 Cal. App. 3d 924, 112 Cal. Rptr. 846 (1974), cert. denied, 419 U.S. 869 (1975)). Protection of Ground Water Quality The addition of water to ground water can affect the quality of the "native" ground water. Ground water quality is the focus of much of environmental law, but there is no comprehensive federal ground water statute. Congress has, however, given EPA the ability to regulate certain types of ground water recharge through the Underground Injection Control (UIC) program of the Safe Drinking Water Act (42 U.S.C. § 300h to 300h-7 (1988)). This act is administered by EPA and by states with approved programs. The act does not protect all ground water, but rather protects, as its name suggests, underground sources of drinking water (USDW), which are aquifers that are used or could be used for public water systems. While there is a general presumption that aquifers of good-quality water are USDWs, the regulations allow exemptions primarily where the aquifer is of poor quality (40 CFR § 146.3 (1992); 40 CFR § 146.4 (1992)). This authority extends to two significant forms of ground water recharge: injection wells for highly treated wastewater and dry wells used to dispose of stormwater runoff. Both are Class V wells, within the terminology of the act. Dry wells are brought within the scheme by the inclusion of "[a]ny dug hole or well that is deeper than its largest surface dimension, where the principal function of the hole is emplacement of fluids" (40 CFR § 144.1(g)(1) (1992)). The dispositive issue controlling whether remediated wastewater is brought within the regulatory system is thus the diameter of the well. Residential septic systems are specifically excluded from the regulations (40 CFR § 144.1(g)(2) (1992)). The regulatory authority given to EPA by the act for Class V wells has not been exercised by the agency, and the regulations now require little more than notification of the entity administering the program and submission of certain information (40 CFR § 146.52(a) (1992); 40 CFR § 144.24 (1992)). The agency administering the program is given authority to take action when a Class V well "may cause a violation of primary drinking water regulations" or where it "may be otherwise adversely affecting the health of persons" (40 CFR § 144.12 (1992)). EPA has yet to exercise further regulatory authority over Class V wells. Even as it moves to do so (58 Fed. Reg. 25,033 (1993)), there is no indication that injection for reuse will be a priority at the agency. Therefore, there is little immediate prospect of federally imposed standards for these types of projects. In any event, the limitations of constructing a regulatory scheme under the frame-

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Ground Water Recharge Using Waters of Impaired Quality A summary of the proposed treatment process and site requirements is presented, in Table 5.2. The proposed regulations prescribe stringent microbiological and chemical constituent limits. For spreading operations, credit is given for chemical constituent removal and removal or inactivation of pathogenic microorganisms during percolation through the vadose zone, and the percolated water must be essentially pathogen-free and meet drinking water maximum contaminant levels after percolation. The proposed regulations specify total organic carbon (TOC) as a surrogate for trace organic constituents that may be of concern. Although TOC is not a measure of specific organic compounds, it is considered to be a suitable measure of gross organic content of reclaimed water for the purpose of determining organic removal efficiency in practice. Based principally on the Scientific Advisory Panel report, DOHS concluded that extracted ground water should contain no more than 1 mg/1 TOC of wastewater origin. This decision is reflected in maximum allowable TOC concentrations in the reclaimed water prior to spreading or injection. Prior to adoption, the proposed regulations are subject to external review and any modifications that DOHS deems appropriate based on comments received. Hence, the proposed regulations may be substantially different from the ground water regulations that are ultimately adopted in California. The wastewater reclamation criteria apply only to the reuse of domestic water. There are currently no regulations dealing with the use of stormwater runoff and irrigation return flow for ground water recharge, and such projects are dealt with on a case-by-case basis. Other Relevant Laws In addition to the laws specifically addressing ground water recharge, two other water protection laws, the Porter-Dolwig Ground Water Basin Protection Law (Cal. Water Code §12922) and the California Safe Drinking Water Act (Cal. Health and Safety Code § 4010), also relate to the use of reclaimed waste-water for ground water recharge. The Ground Water Basin Protection Law seeks to ensure "the correction and prevention of irreparable damage to, or impaired use of, the ground water basins of this state caused by critical conditions of overdraft, depletion, seawater intrusion or degraded water quality" (Cal. Water Code, § 12922). The law applies to projects that, among other things, are used for reclamation of water used to "replenish, recharge or restore a ground water basin... when such basin is relied on as a source of public water supply" (Cal. Water Code § 12921.3). Under section 12923, projects may be reviewed by DWR and evaluated in terms of potential threats to the ground water and the project plans and design criteria

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Ground Water Recharge Using Waters of Impaired Quality may be revised in order to ensure that the ground water is protected (Cal. Water Code § 12923). The California Safe Drinking Water Act is intended to ensure that the state has pure, wholesome, and potable drinking water (Cal Health and Safety Code § 4010). The regulations set forth primary and secondary drinking water standards, which are similar or more stringent than the federal standards, and are administered by DOHS. Operators of public water systems that extract ground water that is partially recharged wastewater must comply with the primary and secondary drinking water standards (Cal. Health and Safety Code § 4017). INSTITUTIONAL ISSUES Many institutional factors affect the viability of ground water recharge projects. In examining these influences, the fact of their mutability should be kept prominent: an uneconomic project can look feasible if subsidies are provided, or an unhelpful legal structure can be changed. Education programs can help shift public opinion. Although the cost of alternative supplies is a critical factor, the existence of WATER CONSERV II, ORANGE COUNTY FLORIDA Water Conserv II is billed as the largest water reclamation project in the world that combines agricultural irrigation and rapid infiltration basins. The project uses water reclaimed form sewage to irrigate citrus groves and to recharge the Upper Floridan aquifer through rapid infiltration basins. It is a cooperative water conservation effort by the city of Orlando, Orange County, and the agricultural community. The system is designed to produce 50 millon gallons of reclaimed water per day from two sewage treatment facilities. The reclaimed water is delivered to citrus grove owners under 20-year contracts for irrigation and frost protection purposes. What is not used for irrigation is routed to rapid infiltration basins for recharge of the Upper Floridan aquifer, the principal source of water for most of Florida The system is designed to provide reclaimed water to 12.000 to 15,000 acres of citrus and to 2,000 acres of rapid infiltration basins. This cooperative effort provides an excellent illustration of how collaborative arrangements can resolve both the sewage disposal and the water supply problems of an area Agricultural users obtain reclaimed water at little or no cost thereby increasing the profitability of their operations. Simultaneously, water supply from the Upper Floridan aquifer is enhanced both by the direct recharge via the rapid infiltration basins and by in lieu recharge," which occurs because agricultural users reduce demand on the aquifer. The result is that there is greater availability of high-quality ground water for the potable water needs of the rapidly growing central Florida area at the same time that the agricultural demands of citrus growers are being met.

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Ground Water Recharge Using Waters of Impaired Quality an entity with a motive to develop the water source is also critical. Thus, in a jurisdiction where ground water is developed for use by individuals (as in a rural agricultural area), and not by a central water district, ground water recharge may not occur because no individual has a sufficient stake to invest in its development. In southern California, in contrast, the Metropolitan Water District is a dominating entity with an interest in water conservation and the use of recharge basins (Tarlock, 1991). While ground water recharge may be an appropriate means of augmenting water supplies, it can also be attractive because of a very different type of imperative. Disposal of wastewater can be expensive, especially with escalating pollution control requirements applied to discharges. These requirements have increased in cost and complexity, and are largely the result of federal and state level decision making. A "no discharge" operation may be appealing to the local government that is operating the wastewater disposal facility, regardless of the downstream ecological consequences. Nonpoint source pollution has historically been exempt from pollution control regulation. There is some likelihood that pollution from nonpoint sources will become the focus of regulation in the future. Thus, for example, EPA's stormwater regulations (40 CFR § 122.26 (1992)) are now bringing stormwater runoff under regulatory control. These newly regulated dischargers face a choice not unlike that faced by industrial facilities 20 years ago: to what media shall the discharge be directed? If regulatory requirements for ground water disposal are less than those for surface water discharges, the use of artificial recharge projects may increase. The statutory exemption of irrigation return flow from the Clean Water Act (33 U.S.C. § 1362(14)) has periodically been subject to criticism because of the constituents found in those discharges. If these sources are subjected to regulation by Congress, pressure might build for alternative disposal methods, including deliberate discharge to ground water. Ground water recharge as a form of conjunctive use offers possible environmental advantages. Dams and reservoirs are criticized on environmental and economic grounds. Ground water storage can provide a means of achieving many of the same ends, but with fewer contentious aspects. Further, ground water storage projects can lessen demands on a river by allowing storage of peak flows, so these can be used at times of low flows. The enthusiasm of a project developer is affected by the regulatory environment. While protracted reviews are no longer unexpected for large-scale projects, shifting regulatory targets can discourage project proponents. The content of regulations is frequently asserted to be less important than the certainty of regulations. For ground water recharge projects, the burden of being the first project in a state or jurisdiction can impose additional requirements on project proponents and discourage innovation. The multiplicity of organizations involved in a typical recharge project might

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Ground Water Recharge Using Waters of Impaired Quality be thought to spell doom for any such project. This is a difficult proposition to test because it is harder to identify projects that never were initiated than to chronicle those that are now operational and therefore have overcome institutional barriers. Some research indicates that the mere multiplicity of actors is not an insurmountable barrier to these projects, when the need is great (Tarlock, 1991). This thesis is not immediately intuitively obvious, but examples abound where a multiplicity of powers successfully cooperate for common ends. Because it can be expensive to research and develop new regulations, federal research into scientific and engineering issues and federal involvement in development of model statutes and guidelines can help states in their evaluation of proposed recharge projects. Needless to say, this research should reflect the substantial experience already garnered by the states and regions. The existence of this regulatory infrastructure can benefit those proposing projects and the public by providing clear guidance as to the jurisdiction's requirements. Whether the federal role should go beyond providing technical assistance is a matter of debate; given the innovation already evidenced by several states, and the variability in physical conditions among the regions of the nation, the merits of an expanded federal role should be evaluated as the pressure to utilize recharge grows. If states are stymied in the adoption of regulatory schemes, adopt regulations that result in health concerns, or ask for federal assistance, then federal regulation might be desirable. Southern California's efforts to address its ground water problems have been the subject of considerable scholarly interest and are instructive in considering how regions have succeeded, despite a multiplicity of actors, in addressing public needs (see Ostrom, 1990). The challenges faced by the region are formidable, including the pressure of a growing population on water supplies, the expense of relying on imported surface water, a lack of controls on ground water mining, the danger of saltwater intrusion, and the sheer number of institutions with a role in water decisions. The solution adopted after many years of effort combined controls on ground water pumping, which were imposed through adjudication rather than state regulation, and the use of ground water recharge. Ground water recharge allowed the aquifers to be used for ground water storage and the replenishment of ground water to prevent saltwater intrusion. Significantly, the local water districts did not take the controlling law as static. In two instances, water producers from the districts pursued statutory changes, most notably securing passage of a statute that authorized them to form a joint district to control pumping, impose fees on pumping, and carry out recharge projects (Ostrom, 1990). What enables one region facing difficult water problems to overcome difficulties and arrive at a workable solution, while another stumbles into expensive and awkward solutions, is a query which confronts many areas of water management. Continuing research by social scientists will bring about a better understanding of the relevant institutional factors and how they interact.

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Ground Water Recharge Using Waters of Impaired Quality RISK COMMUNICATION AND RISK PERCEPTION In the past, risk communication was defined as a one-way transmission of expert knowledge to nonexperts. But this simple image has been replaced. Today, risk communication is seen as an interactive process of exchange of information and opinion among individuals, groups, and institutions. it involves multiple messages about the nature of risk and other messages, not strictly about risk, that express concerns, opinions, or reactions to risk messages or to legal and institutional arrangements for risk management. Risk communication is successful only to the extent that it raises the level of understanding of relevant issues or actions and satisfies those involved that they are adequately informed informed within the limits of available knowledge. Risk perception, or how people judge and react to risk, deals with human values regarding attributes of hazards and benefits. Studies of risk perception, such as the studies cited in this report. typically present technologies, activities. or substances and ask people to consider the risks they feel each presents and to rate them. Analysis of such studies show that people's ratings are affected by certain attributes-such as the potential to harm large numbers of people at once, personal uncontrollability dreaded effects, effects on children reversibility, and perceived involuntariness of exposure—that make those hazards more serious to the public than hazards that lack those attributes. The fact that hazards differ dramatically in their qualitative aspects helps explain why certain technologies or activities, such as nuclear power, evoke more serious public opposition than others, such as motorcycle riding, that cause many more injuries and fatalities. This means that risk perception is value-laden. When lay and expert values differ, reducing different kinds of hazard to a common numerical rating (such as number of fatalities per year) and presenting comparisons only on that metric have great potential to produce misunderstanding and conflict and to engender mistrust of expertise. SOURCE: National Research Council, 1989. PUBLIC ATTITUDES TOWARD THE USE OF RECLAIMED WATER Water reclaimed from municipal wastewater or other sources of impaired quality holds the potential to be a significant source in water-short areas, but public opinion about such uses is a controlling factor (Bruvold, 1981). Indeed, the importance of the attitudes of the public cannot be discounted because the public is ultimately the recipient of. the reclaimed water and it ultimately, albeit often indirectly, bears the burden of the costs of such operations. Thus, experts urge that the public be brought into the technical decision-making process early (Bruvold, 1976) and that communication of potential risks be presented in clear, plain language; be complete and be accurate (riot distorting the risk or minimizing the existence of uncertainty); be oriented to the needs and concerns of the audience; and use risk comparisons cautiously (NRC, 1989). This type of effort

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Ground Water Recharge Using Waters of Impaired Quality can help develop the public's understanding of the issues involved in reclamation of wastewater and educate citizens so they act as informed decision makers. People's attitudes about the reuse of reclaimed water depend on the source and the intended purpose of the reuse, and nonpotable reuse is more acceptable than potable reuse. When drinking water is at issue, indirect potable reuse is more acceptable to the public than direct potable reuse because the water is perceived to be cleansed as it flows in a river, lake, or aquifer (U.S. Environmental Protection Agency, 1992). However, in general the public does not favor potable reuse. For instance, in research designed to determine the attitudes of Californians toward the use of reclaimed water, Bruvold (1976) measured attitudes toward 25 uses of reclaimed water, ranging from high contact uses such as drinking and bathing to low-contact uses such as irrigating golf courses and road construction (Table 5.3). In general, the public accepts the use of reclaimed water for a variety of purposes, but not drinking or other high contact uses. Respondents opposed to various uses ranged from 56 percent who opposed drinking reclaimed water to only 1 percent who opposed the use of such water in road construction. Ground water recharge using reclaimed wastewater was opposed by 23 percent of those surveyed. That study and others (Table 5.3) are remarkably consistent in showing that a majority of about 55 percent do not want to use reclaimed wastewater for drinking, while about 45 percent say they would be willing to accept such reuse (Bruvold, 1975). Nonpotable uses such as toilet flushing and lawn and golf come irrigation were acceptable to most survey respondents. Acceptance of reclaimed water for drinking and other high-contact uses is affected by public perception of the associated health risks: the public is concerned about the perceived quality of the water and whether it might serve to transmit pathogens, viruses, or harmful trace chemicals. Studies show relationships between certain beliefs and attitudes toward the reuse of water: people who believed that their water supply was polluted, that their area faced a water shortage, and that modem technology was available for purifying wastewater were consistently more favorable in attitude toward reuse than those who believed their water supply was not polluted, that their areas did not face shortage, and that modem technology could not reliably purify wastewater (Bruvold, 1975). Research investigating attitudes toward treatment and reuse options found that the public did not favor either (1) minimal treatment followed by ocean disposal or (2) high levels of advanced treatment and subsequent reuse for drinking. Instead, they preferred relatively high levels of treatment followed by a "middle" level of use (e.g., park and greenspace irrigation) (Bruvold, 1981). It is important to note that these surveys indicate that the public was quite willing to accept many uses less intimate than ingestion. A sizable segment of those surveyed (ranging from 56 to 33 percent) did not oppose or was positive toward the use of reclaimed water even for drinking, thus leaving open the possibility of future acceptance of a wider variety of use for reclaimed water. For that

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Ground Water Recharge Using Waters of Impaired Quality TABLE 5-3 Percentage of Respondents Opposed to Various Uses of Reclaimed Water In General Opinion Surveys   Bruvold (1972) (N=972) Stone & Kahle (1974) (N= 1,000) Kasperson et al. (1974) (N=400) Drinking water 56 46 44 Food preparation in restaurants 56 - - Cooking in the home 55 38 42 Preparation of canned vegetables 54 38 42 Bathing in the home 37 22 - Swimming 24 20 15 Pumping down special wells 23 - - Home laundry 23 - 15 Commercial laundry 22 16 - Irrigation of dairy pasture 14 - - Irrigation of vegetable crops 14 - 16 Spreading on sandy areas 13 - - Vineyard irrigation 13 - - Orchard irrigation 10 - - Hay or alfalfa irrigation 8 9 - Pleasure boating 7 14 13 Commercial air conditioning 7 - - Electronic plant process water 5 5 3 Home toilet flushing 4 5 - Golf course hazard lakes 3 8 - Residential lawn irrigation 3 6 - Irrigation of recreation parks 3 - - Golf course irrigation 2 5 2 Irrigation of freeway greenbelts 1 - - Road construction 1 - - Note: dash indicates that particular use was not included in survey. Source: Bruvold (1987). to happen, Bruvold (1976) suggested that "those who wish to demonstrate that reclaimed water is of high quality should initiate highly visible, well publicized demonstrations using reclaimed water for low-contact purposes not likely to be controversial. Such innovations would give technical experts, health officials, and the lay public experiential and scientific evidence that modem technology can provide water that is reliably of high quality in every respect. If these demonstration efforts are successful we will be a long way ahead in developing public acceptance for reclaimed water that might eventually include intimate personal use and consumption."

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Ground Water Recharge Using Waters of Impaired Quality   Olson et al. (1979) (N=244) Bruvold (1981) (N=140) Milliken & Lohman (1983) (N=399) Lohman & Milliken (1985) (N=403) Drinking water 54 58 63 67 Food preparation in restaurants 57 - - - Cooking in the home 52 - 55 55 Preparation of canned vegetables 52 - 55 55 Bathing in the home 37 - 40 38 Swimming 25 - - - Pumping down special wells 40 - - - Home laundry 19 - 24 30 Commercial laundry 18 - - - Irrigation of dairy pasture 15 - - - Irrigation of vegetable crops 15 21 7 9 Spreading on sandy areas 27 - - - Vineyard irrigation 15 - - - Orchard irrigation 10 - - - Hay or alfalfa irrigation 8 - - - Pleasure boating 5 - - - Commercial air conditioning 9 - - - Electronic plant process water 12 - - - Home toilet flushing 7 - 3 4 Golf course hazard lakes 5 8 -   Residential lawn irrigation 6 5 1 3 Irrigation of recreation parks 5 4 - - Golf course irrigation 3 4   o Irrigation of freeway greenbelts 5 - - - Road construction 4 - - - SUMMARY The future of ground water recharge using waters of impaired quality will be crucially affected by the economic, legal, and institutional setting. Indeed, the institutional barriers may prove to be more problematic than any remaining technical constraints. From an economic perspective, aquifer recharge with waters of impaired quality may be more attractive in the future because of the increasing scarcity of new sources of surface water. Also, increasingly stringent waste-water discharge regulations may make the incremental costs of rendering waste-

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Ground Water Recharge Using Waters of Impaired Quality water fit for potable or nonpotable uses quite modest in comparison with the costs of other new sources. The economic feasibility of recharge with waters of impaired quality will vary from situation to situation. Reclaimed waters will be attractive from an economic viewpoint whenever they are the least-cost source of supplemental water. The costs of treatment over and above what is required to meet wastewater discharge standards will be particularly important. However, costs will also be quite sensitive to the distance that reclaimed waters have to be transported for spreading or injection and to the techniques used for spreading or injection. Economic feasibility will also depend on the benefits that the recharge waters ultimately yield. As long as users are willing to defray the full costs of recharge, there is prima facie evidence that the benefits will outweigh the costs. From both an economic and a legal perspective, the need to define fights to both source waters and product waters is paramount. Failure to define fights clearly by itself makes recharge with waters of impaired quality far less attractive than it might otherwise be. From a strictly legal standpoint, the central question is how to formulate policy to protect public health, the public good, and the environment, while not imposing inappropriate or unnecessarily burdensome controls on recharge facilities. Most existing laws focus on the need to protect ground water quality, but there is also a body of law directed at the use of recharge water. State laws governing recharge are highly variable. California and Arizona have detailed and comprehensive sets of laws and regulations, but many other states have not addressed this regulatory problem or have done so inadequately. Although there are federal laws that govern certain aspects of the recharge process, the federal government has not exercised strong leadership in developing appropriate institutions to govern wastewater recharge. For the most part, the development of such institutions has been highly decentralized, and this approach may not prove workable in the future. REFERENCES Argo, D. G., and N. M. Cline. 1985. Groundwater recharge operations at Water Factory 21, Orange County, California. In Artificial Recharge of Groundwater, T. Asano, ed. Boston, Mass.: Butterworth. Brown, G. M., Jr., and R. Deacon. 1972. Economic optimization in a single cell aquifer. Water Resour. Res. 8(3):557-564. Bruvold, W. H. 1975. Human perception and evaluation of water quality. Crit. Rev. in Environ. Cont. 5(2):153-231. Bruvold, W.H. 1976. Using reclaimed water: Public attitudes and governmental policy. In Public Affairs Report, Bulletin of the Institute of Governmental Studies, Vol. 17, No. 3. University of California, Berkeley. Bruvold, W.H. 1981. Community evaluation of adopted uses of reclaimed water. Water Resour. Res. 17:487-490. Bruvold, W. H. 1987. Public evaluation of salient water reuse options. In Proceedings of Water

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Ground Water Recharge Using Waters of Impaired Quality Reuse Symposium IV, Denver, Col. Aug. 2-7, 1987. Denver, Col.: Am. Water Works Assoc. Res. Found. Burness, H. S., and W. E. Martin. 1988. Management of a tributary aquifer. Water Resour. Res. 24(5):1339-1344. Burt, O. R. 1970. Groundwater storage control under institutional restrictions. Water Water Resour. Res. 24(5):1540-1548. California Department of Health. 1973. Position on Basin Plans for Reclaimed Water Uses Involving Ingestion. Water Sanitation Section, California Department of Health. Berkeley, Calif. California Department of Health Services. 1993a. Draft Groundwater Recharge Regulations. Office of Drinking Water Technical Operations Section, California Department of Health Services. Berkeley, Calif. California Department of Health Services. 1993b. Proposed Regulation. California Code of Regulations, Title 22, Division 4, Chapter 3. Office of Drinking Water, California Department of Health Services. Berkeley, Calif. Crook, J. 1985. Regulatory approach to groundwater recharge with reclaimed domestic wastewater. Pp. 1673-1694 in Proceedings of Water Reuse Symposium III, August 26-31, 1984, San Diego, California. Denver, Col.: Amer. Water Works Res. Found. Cummings, R.G. 1970. Some extensions of the economic theory of exhaustible resources. West. J. Econ. 7(3):201-210. Cummings, R.G. 1971. Optimum exploitation of groundwater reserves with saltwater intrusion. Water Resour. Res. 7(6):1415-1424. Gisser, M. 1983. Groundwater: Focusing on the real issue. J. Polit. Econ. 91(4):1001-1027. Hartling, E. C. 1993. Impacts of the Montebello Forebay Groundwater Recharge Project. Bull. Calif. Water Pollut. Contr. Assoc. 29(3):14-26. Iagram, H. M., D. E. Mann, G. D. Weatherford, and H. J. Cortner. 1984. Guidelines for improved institutional analysis in water resources planning. Water Resour. Res. 20(3):323-334. Krautkraemer, J. 1991. Pros and Cons of Ground Water Regulation. Pp. 151-153 in Proceedings: Changing Practices in Ground Water Management—The Pros and Cons of Regulation. Rep. No. 77. Water Resources Center. University of California. McGinnis, M. 1990. Creating a ''new" class of water-regulation of municipal effluent, Arizona Public Service Co. v. Long, 160 Ariz. 429, 773 P.2d 988 (1989), Arizona State L.J. 22(4):987-1002. National Research Council. 1986. Ground Water Quality Protection: State and Local Strategies. Washington, D.C.: National Academy Press. National Research Council. 1989. Improving Risk Communication. Washington, D.C.:National Academy Press. Nellor, M. H., R. B. Baird, and J. R. Smyth. 1984. Health Effects Study—Final Report. NTIS No. PB-84191-568. County Sanitation Districts of Los Angeles County, Whittier, Calif. Ostrom, E. 1990. Governing the Commons: The Evolution of Institutions for Collective Action. New York: Cambridge University Press. Orange County Water District/County Sanitation Districts of Orange County. 1993. A Joint Water Recycling Strategy for Achieving Water Supply Independence. Draft report dated Oct. 8, 1993. p. 19. Provencher, B., and O. R. Burt. 1993. The externalities associated with common property exploitation of groundwater. J. Environ. Econ. Manage. 24(2):139-158. Redding, M. B., and J. F. DuBois. 1990. Arizona's Aquifer Protection Permit Program: A regulatory approach to protecting groundwater. In Proceedings of the Underground Injection Practices Council Research Foundation Conferences/Symposia at Monterey, Calif. December 10-12, 1990. State of California. 1975. A State-of-the An Review of Health Aspects of Wastewater Reclamation for Groundwater Recharge. Prepared by the California State Water Resources Control Board,

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Ground Water Recharge Using Waters of Impaired Quality Department of Water Resources, and Department of Health. Published by the Department of Water Resources, Sacramento, Calif. State of California. 1976. Report of the Consulting Panel on Health Aspects of Wastewater Reclamation for Groundwater Recharge. Prepared by the California State Water Resources Control Board. Published by the Department of Water Resources, Sacramento, Calif. State of California. 1987a. The Porter-Cologne Water Quality Control Act. California State Water Resources Control Board, Sacramento, Calif. State of California. 1987b. Report of the Scientific Advisory Panel on Groundwater Recharge with Reclaimed Wastewater. Prepared for State of California Water Resources Control Board, Department of Water Resources, and Department of Health Services, Sacramento, Calif. State of California . State of California. 1990. Proposed Guidelines for Groundwater Recharge with Reclaimed Municipal Wastewater. Prepared by the California State Water Resources Control Board, Department of Water Resources, and Department of Health Services, Sacramento, Calif. State of California. Tarlock, A. D. 1991. Coordinating Water Resources in the Federal System: The Groundwater-Surface Water Connection, A-118. Washington, D.C.: U.S. Advisory Commission on Intergovernmental Relations. U.S. Environmental Protection Agency, U.S. Agency for International Development. 1992. Manual: Guidelines for Water Reuse. EPA/625/R-92/004. Office of Water, U.S. Environmental Protection Agency. Vaux, H. J., Jr. 1985. Economic aspects of groundwater recharge. Pp. 703-718 in Artificial Recharge of Groundwater. T. Asano, ed. Boston, Mass.: Butterworth Warren, J.P., L. L. Jones, R. D. Lacewell and W. L. Griffin. 1975. External costs of land subsidence in the Houston-Baytown area. Am. J. Agric. Econ. 57(4):450-455. Western States Water Council. 1990. Ground Water Recharge Projects in the Western United States: Economic Efficiency, Financial Feasibility and Legal/Institutional Issues. Denver, Col.: U.S. Department of Interior.