Book Water quality engineering in natural system 19 298

CHAPTER 1 INTRODUCTION

Water is essential for life on Earth, and any changes in the natural quality and distribution of water have ecological impacts that can sometimes be devastating. The sciences of hydrol- ogy and ecology are the scienti fic foundations of water-quality management. Hydrology is the science dealing with the occurrence and movement of water, ecology is the science deal- ing with interactions between living things and their nonliving (abiotic) environment or habitat, and the relationship between hydrology and ecology is sometimes called hydrologic connectivity (Pringle, 2003).

It is widely recognized that the establishment of new hydrologic connections in the landscape and modi fication of natural connectivity in highly modified human-dominated landscapes can have signi ficant ecosystem impacts. For example, the modification of free- flowing rivers for energy or water supply and the drainage of wetlands can have a variety of deleterious e ffects on aquatic ecosystems, including losses in species diversity, floodplain fertility, and bio filtration capability (Gleick, 1993). Specific environmental issues that are of global concern include regional declines in migratory birds and wildlife caused by wet- land drainage, bioaccumulation of methylmercury in fish and wildlife in newly created reservoirs, and deterioration of estuarine and coastal ecosystems that receive the discharge of highly regulated silicon-depleted and nutrient-rich rivers.

Water above land surface (in liquid form) is called surface water, and water below land surface is called ground water. Although surface water and ground water are directly con- nected, these waters are typically considered as separate systems and managed under di fferent rules and regulations. A key feature of any surface-water body is its watershed, which is delineated by topographic high points surrounding the water body, and all surface runo ff within the watershed has the potential to flow into the surface-water body. Consequently, surface-water bodies are the potential recipients of all contamination contained in surface runo ff from all locations within the watershed. For this reason, the

Water-Quality Engineering in Natural Systems, by David A. Chin Copyright © 2006 John Wiley & Sons, Inc.

2 INTRODUCTION

management of water quality in surface waters is best done at the watershed scale rather than at the scale of individual water bodies. This is the watershed approach to water-quality management. The main limitations to implementing the watershed approach are rooted in our inability to quantify most of the sub-watershed-scale contaminant-transport processes that are fundamental to implementing watershed models of water quality. Contaminant inputs into surface waters from the atmosphere are also considered in water-quality man- agement plans (Patterson, 2000). In contrast to surface waters, the quality of ground water is in fluenced primarily by activities on and below the ground surface, and the potential sources of ground-water contamination are determined primarily by overlying land uses and subsurface geology. The concept of a watershed is not applicable to ground water.

Identi fication of some polluted water bodies are obvious to the casual observer, such as the stream shown in Figure 1.1, but some polluted water bodies are not so obvious, such as an apparently pristine lake that is so contaminated with acid rain that the existence of aquatic life is extremely limited.

To put the water-quality problem in perspective, a comprehensive study of the quality of waters in the United States (USGS, 1999) determined that:

• The highest levels of nitrogen occur in streams and ground waters in agricultural areas. Fifteen percent of samples exceeded the drinking-water standard for nitrate nitrogen, 10 mg/L as N.

• Pesticides, primarily herbicides, are found frequently in agricultural streams and ground water. Pesticides found most frequently include atrazine, metachlor, alochlor, and cyanazine.

• Urban streams have the highest frequencies of occurrence of DDT, chlordane, and dieldrin in fish and sediments. Complex mixtures of pesticides are commonly found in urban streams.

FIGURE 1.1 Polluted stream. (From Wetlands Connection Center, 2005. Photo by Suzanne Dilworth Bates.)

PRINCIPLES OF WATER-QUALITY CONTROL

• Concentrations of phosphorus are elevated in urban and agricultural streams. These concentrations commonly exceed 0.1 mg/L.

• Hydrology and land use are the major factors controlling nutrient and pesticide con- centrations in major rivers. Concentrations are proportional to the extent of urban and agricultural land use throughout the watershed. Key factors are soils and land slopes.

• Base flow in rivers originating from ground-water sources can be a major source of nutrients and pesticides to streams.

Aside from these general findings, individual states have their own unique problems with di ffuse sources of pollution: In Wisconsin, waters are polluted by dairy and cranberry farms; in North Carolina, by hogs; in Maryland, by chickens; in southern Florida, by sugar; in Wyoming, by beef cattle; in Oregon, by clear-cutting; and in California, by irrigation return flows.

1.1 PRINCIPLES OF WATER-QUALITY CONTROL

The water-quality-based approach to pollution control provides a mechanism through which the amount of pollution entering a water body is controlled based on the conditions of the water body and the standards set to protect it. The water-quality-based approach to pollution control, illustrated in Figure 1.2, can be viewed as consisting of the following eight stages:

1 Determine protection level

Review/revise state WQS

8 2 Measure progress

Conduct WQ assessment

Modify TMDL if needed (a) Monitor water quality (b) Identity impaired waters

Monitor and enforce compliance

Self-monitoring

Establish priorities

Agency monitoring Rank/target waterbodies Enforcement

6 4 Establish source controls

Evaluate WQS for

Point source permits

targeted waters

NPS programs Reaffirm / revise WQS

5 Define and allocate control responsibilities

TMDL / WLA / LA FIGURE 1.2 Water-quality-based approach to pollution control. (From USEPA, 1994.)

4 INTRODUCTION

1. Determining the protection level requires the development of water-quality stan- dards, which are the bases on which the condition of a water body is assessed.

2. Monitoring and assessing water quality requires a determination of whether water- quality standards are being met, detects pollution trends, and identi fies sources of pollu- tion. According to terminology used in the United States, water bodies not meeting water-quality standards are called impaired waters, and a threatened water body is one that currently meets water-quality standards but for which existing and readily available data and information on adverse declining trends indicate that water-quality standards will probably not be met at some time in the near future (USEPA, 1991b).

3. Establishing priorities involves ranking impaired water bodies based on considera- tions of risk to human health, aquatic life, and wildlife; degree of public interest and sup- port; the recreational, economic, and aesthetic importance of a particular water body; and other relevant considerations.

4. Evaluating water-quality standards involves evaluating the appropriateness of the water quality standards for speci fic waters. It is possible that generally applied standards may be either over- or underprotective for a speci fic water body that has not had an in- depth standards analysis.

5. Defining and allocating control responsibilities establishes the level of control needed to meet water-quality standards and de fines and allocates control responsibilities. The quantity of potential pollutants that can be discharged into any given water body without altering its integrity is called the waste assimilative capacity, and the sum of the waste assim- ilative capacity and the background load is called the loading capacity (USEPA, 1991a). Determining the loading capacity of a receiving body is one of the most important steps in any water-quality-based environmental protection or restoration e ffort. The total maximum daily load (TMDL) is de fined as the maximum amount of a pollutant that may be discharged into a water body and still meet water-quality standards. Mathematical models and/or mon- itoring are used to determine TMDLs for impaired water bodies. Pollutant loadings above the TMDL amount will result in waters exceeding the water-quality standards. The TMDLs include waste-load allocations (WLAs) for point sources, load allocations (LAs) for non- point sources, and a margin of safety (USEPA, 1994). Allocations of pollution loads from point and nonpoint sources are calculated to ensure that water-quality standards are not exceeded, and as such are water-quality-based limits. For each impaired water body, TMDLs are developed by considering all pollution sources within the contributing watershed.

6. Establishing source control implements point-source controls through discharge permits, whereas nonpoint-source controls typically are implemented through state and local laws and regulations. In the United States, discharge permits required by the National Pollution Discharge Elimination System (NPDES) place controls on point-source dis- charges, and these controls may be either technology- or water-quality-based. Technology- based limits are determined by the performance of state-of-the-art treatment systems. For example, secondary municipal wastewater treatment plants are capable of producing

e ffluents with biochemical oxygen demand (BOD) and suspended solids values of less than

30 mg/L, and the discharge limits for municipal wastewaters are usually set at these tech- nology limits, even if the receiving water is capable of assimilating higher levels of BOD and/or suspended solids. In cases where the water-quality requirements are more stringent than the technology-based limits, more advanced treatment is required to meet the ambi- ent water-quality criteria. Under these conditions, the allowable contaminant concentration in the discharge is water-quality-limited.

SOURCES OF WATER POLLUTION

In contrast to point-source controls, nonpoint-source controls usually take the form of required best management practices (BMPs) or other management measures. The lands that are most polluting within a watershed are sometimes called critical lands, and identi fication of such lands is one of the most important tasks in planning, watershed man- agement, and establishing and enforcing TMDLs.

7. Monitoring and enforcing compliance involves the collection of data for assessing compliance with water-quality-based controls (permits) and for evaluating whether the TMDLs, and control actions based on the TMDLs, are consistent with water-quality standards.

8. Measuring progress involves assessing the e ffectiveness of the contaminant-source controls and determining whether water-quality standards have been attained, water-qual- ity standards need to be revised, or more stringent controls should be applied. If water- quality standards are not met, TMDL allocations must be modi fied.

In implementing the principles of water-quality control, it is essential to understand the connection between contaminant-source loading and the water quality. An understanding of pollution abatement resulting from physical, chemical, and/or biological controls and an ability to model these processes are essential in controlling the quality of water in natural systems.

1.2 SOURCES OF WATER POLLUTION

Sources of water pollution are broadly grouped into point sources and nonpoint sources. Point sources are de fined as localized discharges of contaminants and include industrial and municipal wastewater outfalls, septic tank discharges, and hazardous-waste spills. Nonpoint sources of pollution include contaminant sources that are distributed over large areas or are a composite of many point sources, including runo ff from agricultural opera- tions, the atmosphere, and urban runo ff. Surface runoff that collects in storm sewers and discharges via a pipe is still considered nonpoint-source pollution since it originates as di ffuse runoff from the land surface. Pollution loads from nonpoint sources are commonly called diffuse loads. The most widespread nonpoint-source pollutants in the United States are eroded sediments, fertilizers, and pesticides, associated primarily with agricultural operations (Corwin et al., 1999).

Much of the pollution in waterways is caused by nonpoint-source pollution as opposed to point-source pollution. Cunningham (1988) reported that nonpoint sources were the principal contributors to pollution in 76% of lakes and reservoirs in the United States that failed to meet water-quality standards, and USEPA (1997d) reported that nonpoint sources impaired 65% of streams and 45% of estuaries in the United States that failed to meet water-quality standards. A report on the Danube River basin found that nonpoint sources contributed 60% of the nitrogen and 44% of the phosphorus load to the entire river basin (Commission for European Communities, 1994). In developing countries most pollution generated in large urban centers, from farms, deforestation, and land and wetland conver- sion could be classi fied as nonpoint (Novotny, 2003). The Black Sea, Adriatic Sea, Chesapeake Bay, and Gulf of Mexico are all examples of large water bodies a ffected by excessive inputs of nutrients from farming operations and cities located thousands of kilo- meters upstream and brought in by large tributaries—the Danube and Volga Rivers for the

6 INTRODUCTION

Black Sea, the Po River for the Adriatic Sea, the Susquehanna and Potomac Rivers for Chesapeake Bay, and the Mississippi River for the Gulf of Mexico.

Wet-weather discharges refer to discharges that result from precipitation events such as rainfall and snowmelt. Wet-weather discharges include stormwater runo ff, combined- sewer over flows (CSOs), and wet-weather sanitary-sewer overflows (SSOs). Stormwater runo ff collects pollutants such as oil and grease, chemicals, nutrients, metals, and bacteria as it travels across land. CSOs and wet-weather SSOs contain a mixture of raw sewage, industrial wastewater, and stormwater, and have resulted in beach closings, shell fish bed closings, and aesthetic problems.

1.2.1 Point Sources

The identifying characteristic of point sources is that they discharge pollutants into receiv- ing waters at identi fiable single- or multiple-point locations. A typical point source of con- tamination is shown in Figure 1.3. In most countries, these (point) sources are regulated, their control is mandated, and a permit is required for waste discharge. Point sources of contamination that are of concern in managing surface waters are domestic wastewater dis- charges, industrial discharges, and spills.

Domestic Wastewater Discharges Most municipal wastewater treatment plants discharge their e ffluent into rivers, lakes, or oceans. For river discharges of municipal wastewater, the e ffect of the effluent on the dissolved oxygen and nutrient levels in the river are usually of most concern. Decreased oxygen levels in rivers can cause harm to the aquatic life, and increased nutrient levels stimulate the growth of algae, which consume

FIGURE 1.3 Point source of pollution. (From Illinois Leader, 2004.)

SOURCES OF WATER POLLUTION

oxygen. For ocean discharges, pathogen and heavy-metal concentrations are usually of most concern. In particular, pathogenic microorganisms discharged into the ocean can infect humans who come in contact with the ocean water in recreational areas such as beaches. Domestic wastewater discharged from septic tanks contains large numbers of pathogenic microorganisms, with viruses of particular concern because of the ability of viruses to move considerable distances in ground water. Approximately 50 million resi- dents of the United States, 29% of the population, dispose of their sewage by individual on-site (septic) systems. Septic tanks represent the highest total volume of wastewater dis- charged directly to ground water and are the most common source of ground-water con- tamination (Novotny, 2003).

Properly designed, operated, and maintained sanitary-sewer systems collect and trans- port all of the sewage that flows into them to publicly owned treatment works (POTWs). However, occasional unintentional discharges of raw sewage from municipal sanitary sew- ers occur in almost every system. These types of discharges, collectively called sanitary- sewer over flows (SSOs), have a variety of causes, including but not limited to extreme weather, improper system operation and maintenance, and vandalism. There are at least 40,000 SSOs each year in the United States. The untreated sewage from SSOs can con- taminate receiving waters and cause serious water-quality problems. These SSOs can also back up into basements, causing property damage and threatening public health.

Combined-Sewer Overflows Combined-sewer systems are designed to collect rain- water runo ff, domestic sewage, and industrial wastewater in the same pipe. Most of the time, combined-sewer systems transport all of their wastewater to a sewage treatment plant, where it is treated and discharged to a receiving water body. During periods of heavy rainfall or snowmelt, the wastewater volume in a combined-sewer system can exceed the capacity of the sewer system or treatment plant. For this reason, combined-sewer systems are designed to over flow occasionally and discharge excess wastewater directly to nearby streams, rivers, or other water bodies. These over flows, called combined-sewer overflows (CSOs), contain not only stormwater but also untreated human and industrial waste, toxic materials, and debris.

In the United States, combined-sewer systems are remnants of early infrastructure and are typically found in older communities. Combined-sewer systems currently serve approximately 770 communities containing about 40 million people. Most communities with combined-sewer systems (and therefore with CSOs) are located in the northeast and Great Lakes regions and the Paci fic northwest. Figure 1.4 provides a rough illustration of the prevalence of combined-sewer systems in the United States.

Stormwater Discharges Stormwater discharges are generated by runo ff from open land and impervious areas such as paved streets, parking lots, and building rooftops dur- ing rainfall and snow events. Stormwater runo ff often contain pollutants in quantities that could a ffect water quality adversely. A typical stormwater outlet is shown in Figure 1.5. The primary method to control the quality and quantity of stormwater discharges is through the use of best management practices. Although stormwater runo ff is commonly discharged through a single outfall pipe, such discharges are more accurately classi fied as nonpoint pollutant sources.

Industrial Discharges There are a wide variety of industrial wastewaters, and ele- vated levels of nutrients, heavy metals, heat, and toxic organic chemicals are common

8 INTRODUCTION

FIGURE 1.4 Combined-sewer systems in the United States. (From USEPA, 2005b.)

FIGURE 1.5 Stormwater outlet. (From Rogue Valley Council of Governments, 2000.)

in industrial wastewaters. Some industries provide pretreatment prior to discharging their wastewaters either directly into surface waters or into municipal sewer systems for further treatment in combination with domestic wastewater. In many countries outside the United States, industries are permitted to discharge their wastewater without ade- quate pretreatment, and the resulting human and environmental impacts are usually noticeable.

SOURCES OF WATER POLLUTION

FIGURE 1.6 Con fined animal feeding operation. (From State of Arkansas, 2005.)

Animal Feeding Operations Concentrated animal feeding operations (CAFOs) are considered point sources of contamination. To be considered a CAFO, a facility must first

be de fined as an animal feeding operation (AFO), where animals are kept and raised in con fined areas. A typical AFO is shown in Figure 1.6. The following conditions are typi- cal of AFOs: (1) animals have been, are, or will be stabled or con fined and fed or main- tained for a total of 45 days or more in any 12-month period; and (2) crops, vegetation, forage growth, or postharvest residues are not sustained in the normal growing season over any portion of the lot or facility.

There have been substantial changes in the U.S. animal production industry over the past several decades. Although the total number of AFOs has decreased, overall produc- tion has increased. As a result, CAFOs are increasing in size and generating consider- ably more waste requiring disposal over more limited areas. These operations are expanding to the central and southwestern regions of the United States, where land is less expensive and populations are relatively sparse. CAFO waste releases in the eastern United States have prompted a closer evaluation of their environmental impact on sur- face waters.

Spills Spills and accidental or intentional releases can occur in a variety of ways. Transportation accidents on highways and rail freight lines can result in major chemi- cal spills, and accidental releases at petroleum-product storage installations are another common source of accidental spills. Leaks and spills from underground storage tanks and piping into the ground water are of special concern because these releases may remain undetected for long periods of time.

1.2.2 Nonpoint Sources

Nonpoint sources of contamination generally occur over large areas and because of their di ffuse nature, are more complex and difficult to control than point sources. Nonpoint-source

10 INTRODUCTION

TABLE 1.1 Strength of Various Point and Nonpoint Sources a

Suspended Total Total Total BOD 5 Solids Nitrogen Phosphorus

Coliforms Source

(mg/L) (MPN/100 mL) Urban stormwater 10–250 (30) 3000–11,000 (650) 3–10

(mg/L)

(mg/L)

(mg/L)

0.2–1.7 (0.6) 10 3 –10 8 Construction-site NA

NA runo ff Combined-sewer 60–200

10 5 –10 7 over flows Light industrial

10 area Roof runo ff

10 2 Typical untreated

10 7 –10 9 sewage Typical POWT b (20)

10 4 –10 6 e ffluent

a Numbers in parentheses indicate mean. NA, not available or unreliable. b Publicly owned treatment works with secondary (biological) treatment.

pollution is a direct result of land-use patterns, so many of the solutions to pollution by nonpoint sources lie in finding more effective ways to manage the land and stormwater runo ff. Much nonpoint-source pollution occurs during rainstorms and spring snowmelt, resulting in large flow rates that make treatment even more difficult. Federal and state gov- ernments do not play a major role in local land-use decisions; therefore, local governments must be responsible for maintaining water quality through nonpoint-source controls. Nonpoint sources of contamination that must generally be considered in managing water bodies are agricultural runo ff, livestock operations, urban runoff, landfills, and recreational activities.

Runo ff from urban and agricultural areas are the primary sources of surface-water pollution in the United States (USEPA, 2000b). Ground-water contamination originating from septic tanks, leaking underground storage tanks, and waste-injection wells is quite common and are of particular concern when ground water is the source of domestic water supply. The strengths of various sources of water pollution are shown in Table 1.1. It is clearly apparent that pollutants at high concentrations can enter water bodies from

a variety of sources, and control of these sources is central to e ffective water-quality management.

Agricultural Runoff Application of pesticides, herbicides, and fertilizers are all agricul- tural activities that in fluence the quality of both surface and ground waters. In the United States, certain pesticides and herbicides are banned because of their toxicity to humans or their adverse e ffect on the environment. The application of fertilizers is of major concern because dissolved nutrients in surface runo ff accelerate growth of algae and depletion of oxy- gen in surface waters. Nitrogen, in the form of nitrates, is a contaminant commonly found in ground water underlying agricultural areas and can be harmful to humans. Erosion caused by improper tilling techniques is another agricultural activity that can adversely a ffect water quality through increased sediment load, color, and turbidity (AWWA, 1990).

SOURCES OF WATER POLLUTION

FIGURE 1.7 Livestock in a stream. (From State of Arkansas, 2005.)

Livestock Feedlots have been shown to contribute nitrates to ground water, and patho- genic microorganisms to surface waters. Overgrazing eliminates the vegetative cover that prevents erosion, increasing the sediment loading to surface waters. In some extreme cases, livestock are allowed to wade in and cause direct contamination of streams. Such a circumstance is shown in Figure 1.7. This practice should be avoided as much as possible, since the direct pollution of streams by pathogens such as Cryptosporidium parvum is a likely and undesirable consequence.

Urban Runoff Urban runo ff contains contaminants that are washed from pavement sur- faces and carried to surface-water bodies. Contaminants contained in urban runo ff include petroleum products, metals such as cadmium and lead from automobiles, salt and other deicing compounds, and silt and sediment from land erosion and wear on road and side- walk surfaces. Bacterial contamination from human and animal sources is also often pres- ent. The initial “ flushing” of contaminants during storm events typically creates an initial peak in contaminant concentration, with diminishing concentration as pollutants are washed away (AWWA, 1990).

A major factor associated with impairment of waters in the United States is the amount of impervious area that is directly connected to urban runo ff systems (USEPA, 2002b), and such a connection is shown in Figure 1.8. According to Schueler (1995), there is a strong correlation between percent imperviousness of a watershed and stream health. Schueler (1995) further reported that stream degradation can occur when a water- shed becomes about 10% impervious, and degradation becomes unavoidable at 30% imperviousness.

Landfills Leachate from land fills can be a source of contamination, particularly for ground water. Water percolating through a land fill (leachate) contains many toxic con- stituents and is typically controlled by capping the land fill with a low-permeability cover

12 INTRODUCTION

FIGURE 1.8 Surface runo ff into a drainage system. (From State of Vermont, 2005.)

and installing a leachate-collection system. Many older land fills do not have leachate- collection systems.

Recreational Activities Recreational activities such as swimming, boating, and camp- ing can have a signi ficant impact on water quality. The impact of human activities has typ- ically been reported in terms of increased levels of pathogenic microorganisms (AWWA, 1990).

1.3 LAWS AND REGULATIONS

Most water-control protocols are motivated directly or indirectly by environmental regula- tions. Consequently, to gain a proper understanding of water-control practice, one must have a good understanding of environmental regulations.

In the United States, Congress makes laws, and to put these laws into e ffect, Congress authorizes certain government agencies, such as the U.S. Environmental Protection Agency (USEPA), to create and enforce regulations to implement these laws. The creation of a law begins when a bill is proposed by a member of Congress. If both houses of Congress approve a bill, it goes to the President, who has the option to either approve (sign) it or veto it. If approved, the new law is called an act, and the text of the act is known as a public statute. Once an act is passed, the Government Printing O ffice incorporates the new law into the United States Code, which codi fies (categorizes and compiles) all federal legislation. Authorized regulatory and enforcement agencies—such as the USEPA— identify the need for regulations to support implementation of the act passed by Congress. Proposed regulations are listed in the Federal Register so that the public can provide com- ments to the agency. After considering all public comments and making appropriate modi fications to proposed regulations, a final rule is issued and published in the Federal Register . Once a regulation is completed and has been published in the Federal Register as

a final rule, it is codified by being published in the Code of Federal Regulations (CFR). The CFR is the o fficial record of all regulations created by the federal government and is

LAWS AND REGULATIONS

divided into 50 volumes called titles, each of which focuses on a particular area. Almost all environmental regulations appear in Title 40, usually abbreviated as simply 40 CFR. Each CFR title is divided into various sections; for example, the baseline regulations deal- ing with stormwater discharges into waters of the United States are found in 40 CFR 122, and speci fic permit requirements are found in 40 CFR 122.26. The most important federal laws governing the quality of ground and surface waters in the United States are the Clean Water Act (CWA) and the Safe Drinking Water Act (SDWA).

Programs mandated by both the CWA and SDWA are administered at the federal level by the U.S. Environmental Protection Agency, and these programs are usually imple- mented through corresponding individual state programs. The CWA allows the delegation of many permitting, administrative, and enforcement aspects of the law to state govern- ments. In states with the authority to implement CWA programs, the USEPA still retains oversight responsibilities. In addition to the implementation of federal laws and regula- tions, state programs provide protection of public water supplies through water codes, san- itary regulations, regulation of inland wetland areas, and other means of watercourse and ground-water protection (AWWA, 1990). At the local level, municipal and county ordi- nances can provide signi ficant protection through land-use controls that regulate develop- ment activities on key watershed areas.

1.3.1 Clean Water Act

The Clean Water Act, originally enacted in 1972, is intended to restore and maintain the physical, chemical, and biological integrity of waters of the United States. The Clean Water Act applies to surface waters, including rivers, lakes, estuaries, wetlands, and oceans, and focuses primarily on establishing water-quality standards and regulations to control discharges into surface waters. Major requirements of the Clean Water Act are:

• States must set water-quality standards to protect designated uses of all natural water bodies in the state.

• States must prepare and submit (to the USEPA) an annual report on the quality of all waters in the state.

• States must submit (to the USEPA) lists of surface waters that do not meet applicable water-quality standards after implementation of technology-based limitations. Such waters are called impaired waters. States must establish total maximum daily loads (TMDLs) for impaired waters on a prioritized schedule that considers the severity of the pollution and the uses to be made of such waters.

• The federal government must set industrywide, technology-based e ffluent standards for dischargers.

• All dischargers must obtain a permit issued by the federal government or authorized states that speci fies discharge limits under the National Pollutant Discharge Elimination System (NPDES). The discharge limits are typically the stricter of the water-quality- based and technology-based limits.

Water-quality standards are the foundation of the water-quality-based pollution control program mandated by the Clean Water Act. Water-quality standards de fine the goals for a water body by designating its uses, setting criteria to protect those uses, and establishing provisions to protect water bodies from pollutants. Point discharges into water bodies that

14 INTRODUCTION

meet their water-quality standard are typically regulated using technology-based e ffluent standards, whereas discharges into impaired waters are regulated for each pollutant based on a total maximum daily load (TMDL), which is the amount of a contaminant that a water body can receive and still meet the water-quality standard. For each pollutant, the TMDL includes contributions from both point and nonpoint sources. Dissolved-oxygen concen- tration and algal biomass (or chlorophyll a) are the most commonly applied assessment endpoints in TMDLs (Tung, 2001).

1.3.2 Safe Drinking Water Act

The Safe Drinking Water Act (SDWA) was enacted in 1974 to protect public health by regulating the nation’s public drinking-water supply. The law was amended in 1986 and 1996 and requires many actions to protect drinking water and its sources. The SDWA applies to every public water system in the United States, and there are currently more than 160,000 public water systems. The SDWA does not regulate private wells that serve fewer than 25 persons. Major programs mandated by the SDWA that relate to water-qual- ity control in natural waters are drinking-water standards, source-water protection, and underground injection control.

Drinking-Water Standards Under the authority of the SDWA, the USEPA has prom- ulgated national primary drinking-water standards for certain radionuclide, microbiologi- cal, organic, and inorganic substances. These standards establish maximum contaminant levels (MCLs), which specify the maximum permissible level of a contaminant in water that may be delivered to a user of a public water-supply system. MCLs are established based on consideration of a range of factors, including not only the health e ffects of the contaminants but also the treatment capability, monitoring availability, and costs. In some cases, MCLs are replaced by treatment techniques (TTs), which are procedures that pub- lic water-supply systems must employ to ensure contaminant control. Required treatment techniques for pathogens are contained in the Surface Water Treatment Rule (SWTR) and the coliform standard. The SWTR requires that surface water, and ground water under the direct in fluence of surface water, undergo some combination of disinfection and filtration to meet the following criteria:

• A minimum of 99.9% of Giardia lamblia and 99.99% of viruses are to be killed or inactivated.

• The turbidity must be maintained at less than 5 nephelometric turbidity units (NTU) at all times and less than 1 NTU in 95% of daily samples.

• The total heterotrophic bacterial level, as determined by plate count, must be less than 500 colonies per milliliter.

The coliform standard requires that no more than 5% of water samples test positive for col- iforms in a month, and of those positives, that there be no samples that test positive for fecal coliforms.

Secondary drinking water standards are nonenforceable guidelines that are based on potential adverse cosmetic e ffects, such as skin discoloration and laundry staining, or aes- thetic e ffects such as taste, odor, and color. Drinking-water standards apply to public water systems, which provide water to at least 15 connections or 25 persons at least 60 days out

LAWS AND REGULATIONS

of the year (most cities, towns, schools, businesses, campgrounds, and shopping malls are served by public water systems). The 10% of Americans whose water comes from private wells (individual wells serving fewer than 25 persons) are not protected by these federal standards. People with private wells are responsible for making sure that their own drink- ing water is safe. Bottled water is regulated by the U.S. Food and Drug Administration as

a food product and is required to meet standards equivalent to those that the USEPA sets for drinking water.

Source-Water Protection Under provisions of the Safe Drinking Water Act, the USEPA also establishes minimum water-quality criteria for water that may be taken into a water-supply system. All states are required to develop source-water assessment plans (SWAPs) to protect public water supplies from contaminant sources within the catchment area of the drinking-water intake. This catchment area de fines the source-water protection area (SWPA) of the intake. Key components of SWAPs are as follows:

1. Delineation of the source-water protection area. For ground-water systems, available information about ground-water flow and recharge is used to determine the source-water protection area around a well or well field. Such areas are called wellhead protection areas. Wellhead protection areas are typically divided into three zones, with an inner zone given the most protection, an intermediate zone where detailed contaminant inventories are con- ducted and best management practices required, and an outer zone where the potential impact of contaminants on drinking-water intakes is regarded as minimal. The inner zone is usually delineated using a distance criterion, the intermediate zone (also known as the inventory region) delineated by time of travel, and the outer zone delineated by a hydroge- ologic boundary. For surface-water intakes drawing water from a stream, river, lake, or reservoir, the land area in the watershed upstream of the intake de fines the source-water pro- tection area. Surface-water intakes commonly have two protection zones, an inner zone that is typically delineated by an upstream distance or travel time (based on the average annual high flow) plus a minimum buffer width. Outer zones are typically delineated by watershed boundaries. Water-supply wells classi fied as ground water under the direct influence of sur- face water (GWUDI) are treated as surface-water sources for delineation purposes.

2. Inventory of actual and potential sources of contamination. Sources of pollutants that could potentially contaminate the water supply are identi fied. This inventory usually results in a list of facilities and activities within the delineated area that may release con- taminants into the underground water supply (for wells) or the watershed of the river or lake (for surface-water sources). Some examples of potential pollutant sources include land fills, underground or aboveground fuel storage tanks, residential or commercial septic systems, urban runo ff from streets and lawns, farms and other entities that apply pesticides and fertilizers, and sludge-disposal sites.

3. Determination of the susceptibility of the water source to contamination. Susceptibility is de fined by the USEPA as “the potential for a public water supply to draw water contaminated by inventories sources at concentrations that would pose concern” (USEPA, 1997c). Susceptibility determinations are typically based on the fate and trans- port of contaminants within the SWPA, and establish the likelihood of contamination of the water supply by potential sources of contamination. This critical step helps local deci- sion makers consider priority approaches for protecting the drinking-water supply from contamination. It is common to prioritize the potential for contamination from the

16 INTRODUCTION

speci fic potential contamination sources or from individual chemicals that could pollute the water. In some cases, a susceptibility ranking of high, medium, or low is assigned to each pollutant source.

4. Releasing the results of the assessments to the public. After the source-water assess- ment for a particular water system is completed, the information must be summarized for the public. Such summaries help communities better understand the potential threats to their water supplies and identify priority needs for protecting the water from contamination. Local communities, working in cooperation with local, regional, and state agencies, can use the information gathered through the assessment process to create broader source- water protection programs to address current and future threats to the quality of their drinking-water supplies.

Communities use a wide array of source-water protection methods to prevent contami- nation of their drinking-water supplies. One management option involves regulations, such as prohibiting or restricting land uses that may release contaminants in critical source- water protection areas. To go along with these regulations, many communities hold local events and distribute information to educate and encourage citizens and businesses to recy- cle used oil, limit their use of pesticides, participate in watershed cleanup activities, and engage in a variety of other prevention activities. Another approach to source-water pro- tection is to purchase land or create conservation easements to serve as protection zones near drinking-water sources.

The use of prescribed bu ffer zones and travel times to protect surface-water intakes and the use of travel times to protect ground-water intakes are the most common approaches to controlling the susceptibility of drinking-water intakes to contamination (USEPA, 1997a, b). A typical riparian (river) bu ffer zone consisting of a forested area is shown in Figure 1.9. Bu ffer zones can be created through utility ownership or usage restrictions,

FIGURE 1.9 River with an adjacent (riparian) bu ffer. (From NRCS, 2005g.)

LAWS AND REGULATIONS

thereby providing for filtration of runoff through natural vegetation. The required buffer areas take into account exposure to contamination and the degree of treatment provided by the bu ffer. Wetlands are frequently used as buffers for water-supply intakes, and preserva- tion of wetlands maintains the natural filtration and cleansing provided by these critical areas.

Underground Injection Control Program The underground injection control (UIC) program provides safeguards such that injection wells do not endanger underground sources of drinking water (USDWs). Facilities across the United States discharge into underground formations a variety of hazardous and nonhazardous fluids via more than 800,000 injection wells, and a typical injection well is shown in Figure 1.10. Agricultural operations and the chemical and petroleum industries could not exist without underground injection wells since it is frequently cost-prohibitive to treat and release to surface waters the large amounts of wastes that these industries produce each year. When injection wells are properly sited, constructed, and operated, these wells are an e ffective and environmen- tally safe alternative to surface disposal.

An injection well is de fined as a bored, drilled, or driven shaft whose depth is greater than the largest surface dimension; a dug hole whose depth is greater than the largest sur- face dimension; an improved sinkhole; or a subsurface fluid distribution system. This

de finition covers a wide variety of injection practices, ranging from more than 140,000 technically sophisticated highly monitored wells that pump fluids into isolated formations up to 2 miles below Earth’s surface to the far more numerous on-site drainage systems,

FIGURE 1.10 Typical injection well. (From Alberta Energy and Utilities Board, Alberta Geological Survey, 2005.)

18 INTRODUCTION

such as septic systems, dry wells, and stormwater wells, that discharge fluids a few meters underground.

USEPA groups underground injection wells into five classes for regulatory control pur- poses. Each class includes wells with similar functions, construction, and operating fea- tures, so that technical requirements can be applied consistently to the class:

• Class I wells: inject hazardous and nonhazardous fluids (industrial and municipal wastes) into isolated formations beneath the lowermost underground source of drink- ing water (USDW). Because these wells inject hazardous waste, class I wells are the most strictly regulated and are regulated further under the Resource Conservation and Recovery Act (RCRA).

• Class II wells: inject brines and other fluids associated with oil and gas production. • Class III wells: inject fluids associated with solution mining of minerals. • Class IV wells: inject hazardous or radioactive wastes into or above a USDW and are

banned unless authorized under other statutes for ground-water remediation. • Class V wells: include all underground injection not included in classes I through IV.

Generally, most class V wells inject nonhazardous fluids into or above a USDW and are on-site disposal systems such as floor and sink drains, which discharge to dry wells, septic systems, leach fields, and drainage wells. Injection practices or wells that are not covered by the UIC Program include single-family septic systems and cesspools as well as nonresidential septic systems and cesspools serving fewer than

20 persons that inject only sanitary wastewater. All injection wells are not waste-disposal wells. Some class V wells, for example, inject

surface water to replenish depleted aquifers or to prevent saltwater intrusion. Some class

II wells inject fluids for enhanced recovery of oil and natural gas. Most injection wells have the potential to inject fluids that may cause a public water system to violate drinking water standards. In general, the UIC program prevents contam- ination of water supplies by setting minimum requirements for state UIC programs. A basic concept of USEPA’s UIC program is to prevent contamination by keeping injected fluids within the intended injection zone, or in the case of injection directly or indirectly into a USDW, the fluids must not endanger or have the potential to endanger a current or future public water supply. Most of the minimum requirements that a ffect the siting of an injection well and the construction, operation, maintenance, monitoring, testing, and finally, the closure of the well, are designed to address these concerns. All injection wells require authorization under general rules or speci fic permits, and most states have primary enforcement authority (primacy) for the UIC program.

1.4 STRATEGY FOR WATER-QUALITY MANAGEMENT

The strategy for water-quality management in the United States is dictated primarily by the Clean Water Act and has three major components:

1. Designate the use of each natural water body.

2. Establish water-quality criteria to protect the designated uses.

3. Maintain a policy of antidegradation in executing steps 1 and 2.

STRATEGY FOR WATER-QUALITY MANAGEMENT

Regulatory categories of designated uses include public water supply, recreation, and propagation of fish and wildlife; other uses, such as navigation and irrigation, can also be speci fied. For each designated use, water-quality criteria are established by the state with the approval of the USEPA. Comparing the quality of a water body with the criteria cor- responding to its designated use is called water-body assessment. If the water-quality cri- teria are met by the water body, the designated use is attained.

1.4.1 Use-Attainability Analysis

If the water-quality criteria are not met, the designated use has not been attained and a use- attainability analysis (UAA) must be done. The primary objectives of a UAA are to deter- mine what maximum pollutant loads [expressed as total maximum daily loads (TMDLs)] are consistent with meeting the water-quality criteria and whether limiting these loads are feasible from a socioeconomic viewpoint. Therefore, a UAA has three components: (1) water-body assessment, (2) determination of total maximum daily load, and (3) socioeco- nomic analysis. Possible outcomes of a use-attainability analysis are that the designated use (a) is attainable, (b) is not attainable and should be downgraded, or (c) is more than attainable and should be upgraded. Acceptable reasons for changing the designated use and/or water-quality criteria of a water body are:

• Naturally occurring pollutant concentrations prevent attainment of the use. • Natural, ephemeral, intermittent, or low flow or water levels prevent the attainment of

the use unless these conditions are compensated for by the discharge of a su fficient volume of e ffluent discharge without violating conservation requirements.

• Human-caused conditions or sources of pollution prevent the attainment of the use and cannot be remedied or would cause more environmental damage to correct than to leave in place.

• Dams, diversions, or other types of hydrologic modi fications preclude the attainment of the use and its feasibility to restore the water body to its original condition or to operate such modi fication in a way that would result in the attainment of the use.

• Physical conditions related to the natural features of the water body, such as the lack of proper substrate, cover, flow, depth, pools, riffles, and the like, unrelated to water quality, preclude attainment of aquatic-life protection uses.

• More stringent controls would result in substantial and widespread adverse societal and economic impact.

1.4.2 Total Maximum Daily Load Process

The TMDL process is the preferred planning process in situations where simple control of point sources by permits based on technology-based standards or on waste load allocations alone would fail to accomplish water-quality goals in water-quality-limited receiving waters. The outcome of this process is a watershed management plan that puts controls on sources of pollution located within the watershed. Management options in water-quality- limited (impaired or threatened) waters are as follows (Novotny, 1996, 1999):

1. Reduction of point-source loads beyond those mandated by technology-based effluent standards. In this case, the entire burden of abatement is placed on point-source dischargers

20 INTRODUCTION

by issuing TMDL-based point-discharge (NPDES) permits. These permits are more stringent than those mandated by technology-based e ffluent standards.