Tietenberg Tom, Lewis Lynne. Environmental & Natural Resource Economics

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471

Water Pollution

It was the best of times, it was the worst of times, it was the age of

wisdom, it was the age of foolishness, it was the epoch of belief, it was the

epoch of incredulity . . .

—Charles Dickens, A Tale of Two Cities (1859)

Introduction

While various types of pollution share common attributes, important differences

are apparent as well. These differences form the basis for the elements of policy

unique to each pollutant. We have seen, for example, that although the types of

pollutants emitted by mobile and stationary sources are often identical, the policy

approaches differ considerably.

Water pollution control has its own unique characteristics as well. The following

stand out as having particular relevance for policy:

1. Recreation benefits are much more important for water pollution control

than for air pollution control.

2. Large economies of scale in treating sewage and other wastes create the

possibility for large, centralized treatment plants as one control strategy,

while for air pollution, on-site control is the standard approach.

3. Many causes of water pollution are more difficult to trace to a particular

source. Runoff from streets and agriculture as well as atmospheric deposition

of pollutants are major diffuse sources of water pollution. Control of these

sources adds additional complexities for water pollution control.

These characteristics create a need for yet another policy approach. In this

chapter we explore the problems and prospects for controlling this unique and

important form of pollution.

472 Chapter 18 Water Pollution

Nature of Water Pollution Problems

Types of Waste-Receiving Water

Two primary types of water are susceptible to contamination. The first, surface water,

consists of the rivers, lakes, and oceans covering most of the earth’s surface. Historically,

policy makers have focused almost exclusively on preventing and cleaning up

lake and river water pollution. Only recently has ocean pollution received the

attention it deserves.

Groundwater, once considered a pristine resource, has been shown to be

subject to considerable contamination from toxic chemicals. Groundwater is water

beneath the earth’s surface in soils or rocks, or in geological formations that are

fully saturated.

Groundwater is a vast natural resource. It has been estimated that the reserves of

groundwater are approximately 88 times the annual flow of surface water.

Groundwater is used primarily for irrigation and as a source of drinking water.

While surface water also serves as a significant source of drinking water, it has

many other uses as well. Recreational benefits, such as swimming, fishing, and

boating, are important determinants of surface water policy in areas where the water

is not used for drinking.

Sources of Contamination

Whereas some contamination has been accidental, the product of unintended

and unexpected waste migration to water supplies, a portion of the contamina-

tion was deliberate. Watercourses were simply a convenient place to dump

municipal or private sewage and industrial wastes. Along the shoreline of many

lakes or rivers, pipes dumping human or industrial wastes directly into the

water were a common occurrence before laws limiting this activity were

enacted and enforced.

For lake and river pollution policy purposes, it is useful to distinguish between

two sources of contamination—point and nonpoint—even though the distinction is

not always crystal clear. Point sources generally discharge into surface waters at a

specific location through a pipe, outfall, or ditch, while nonpoint sources usually affect

the water in a more indirect and diffuse way. Examples of nonpoint source pollution

include the runoff of fertilizers and pesticides from lawns and farms after rainstorms.

From the policy point of view, nonpoint sources are more difficult to control

because both the source and timing are hard to predict and, as such, they have

received little legislative attention until recently. As a result of the gains made in

controlling point sources, nonpoint sources now compose over half of the waste

load borne by the nation’s waters.

Contamination of groundwater occurs when polluting substances leach into a

water-saturated region. Many potential contaminants are removed by filtration and

adsorption as the water moves slowly through the layers of rock and soil. Toxic

organic chemicals are one major example of a pollutant that may not be filtered out

473Nature of Water Pollution Problems

during migration. Once these substances enter groundwater, very little, if any,

further cleansing takes place. Moreover, since the rate of replenishment for many

groundwater sources, relative to the stock, is small, very little mixing and dilution

of the contaminants occur.

Rivers and Lakes. The most important nonpoint sources of pollution for rivers

and lakes are agricultural activity, urban stormwater runoff, silviculture, and

individual disposal systems. Contamination from agriculture includes eroded

topsoil, pesticides, and fertilizer. Urban stormwater runoff contains a number of

pollutants, including, typically, high quantities of lead. Forestry, if not carefully

managed, can contribute to soil erosion and, by removing shade cover, could have a

large impact on the temperature of normally shaded streams. In some developing

countries, more than 95 percent of urban sewage is discharged into surface waters

without treatment.

Groundwater. The contamination of groundwater supplies usually results from

the migration of harmful substances from sites where high concentrations of

chemicals can be found. These include industrial waste storage sites, mines,

landfills, and farms.

Defining Efficient Water Pollution Control. Recall that the efficient allocation

of uncontaminated water requires marginal benefits to be equalized across all uses

(illustrated in Figure 9.3). However, if return flows are contaminated, this can alter

the efficient allocation.

Figure 18.1 demonstrates the effect of return flow contamination on the

efficient allocation in the case of two users: an upper basin (UB) user and a

downstream lower basin (LB) user. Efficiency dictates that water should be

allocated at the point of equal marginal benefits across the two users. If the two

users have identical marginal benefits for uncontaminated water, the two users

should receive equal amounts of water (Figure 9.3). However, subtracting the

effect of contaminated return flows from the upper basin marginal benefit

function (MB

UB´

) (internalizing this externality) changes the efficient allocation to

one with unequal sharing. In particular, more water would be allocated to the

lower basin user (Q

LB´

) and less to the upper basin user (Q

UB´

). (See Bennett (2000)

for a more detailed discussion.) Accounting for water quality can be an important

and often-overlooked factor in allocation decisions.

Ocean Pollution. Two primary sources of ocean pollution are oil spills and

ocean dumping. Oil spills from tankers have become less frequent and have

Return flow is a measure of the unused portion of water. For example, in agriculture, water withdrawal

is the amount of water taken from a source and applied to a field. Consumptive use is the amount

actually used by the plant. Return flow is the unconsumed portion that will eventually return to the

watercourse and is frequently claimed by a downstream user. Return flows will bring with them leached

contaminants, pesticides, fertilizers, and salts from the soil.

474 Chapter 18 Water Pollution

1970

1973

1976

1979

1982

1985

1988

1991

1994

1997

2000

2003

2006

2009

100

Number of Oil Spills per Year

Ye a r

7–700 tons

>700 tons

FIGURE 18.2 The Decreasing Frequency of Oil Spills

Source of data

: International Tanker Owners Pollution Federation Limited Web site: http://www.itopf.com/

information-services/data-and-statistics/statistics/index.html.

= MB

UB+LB

Mean Flow

Acre- Feet

′

= Q

′′

UB + LB

′

FIGURE 18.1 Economic Efficiency When Return Flows Are Contaminated

Source

: Adapted from “The Integration of Water Quality into Transboundary Allocation Agreements:

Lessons from the Southwestern United States,” by Lynne Lewis Bennett.

Agricultural Economics

Vol. 24 (2000): 113–125.

475Nature of Water Pollution Problems

decreased in magnitude since 1970 (see Figure 18.2). Spills, however, are still not

uncommon, as shown in Table 18.1, which lists the largest spills. Various

unwanted by-products of modern life have also been dumped into ocean waters

based upon the mistaken belief that the vastness of the oceans allowed them

to absorb large quantities of waste without suffering noticeable damage. Dumped

materials have included sewage and sewage sludge, unwanted chemicals, trace

metals, and even radioactive materials.

TABLE 18.1 Notable Oil Spills from Tankers

Rank

Spill Size

(tons) Ship Name Year Location

287,000

Atlantic Empress

1979 Off Tobago, West Indies

2 260,000

ABT Summer

1991 700 nautical miles off Angola

3 252,000

Castillo de Bellver

1983 Off Saldanha Bay, South Africa

4 223,000

Amoco Cadiz

1978 Off Brittany, France

5 144,000

Haven

1991 Genoa, Italy

6 132,000

Odyssey

1988 700 nautical miles off Nova Scotia, Canada

7 119,000

Torrey Canyon

1967 Scilly Isles, the United Kingdom

8 115,000

Sea Star

1972 Gulf of Oman

9 100,000

Irenes Serenade

1980 Navarino Bay, Greece

10 100,0 00

Urquiola

1976 La Coruna, Spain

11 95,000

Hawaiian Patriot

1977 300 nautical miles off Honolulu

12 95,000

Independenta

1979 Bosphorus, Turkey

13 88,000

Jakob Maersk

1975 Oporto, Portugal

14 85,000

Braer

1993 Shetland Islands, the United Kingdom

15 80,000

Khark 5

1989 120 nautical miles off Atlantic coast of Morocco

16 74,000

Aegean Sea

1992 La Coruna, Spain

17 72,000

Sea Empress

1996 Milford Haven, the United Kingdom

18 72,000

Katina P

1992 Off Maputo, Mozambique

19 70,000

Nova

1985 Off Kharg Island, Gulf of Iran

20 63,000

Prestige 2002

Off Galicia, Spain

35 37,000

Exxon Valdez

1989 Prince William Sound, Alaska, the United States

Source

: International Tanker Owners Pollution Federation Limited Web site: http://www.itopf.com/information-services/data-and-statistics/

statistics/Reprinted with permission from ITOPF.

476 Chapter 18 Water Pollution

Types of Pollutants

For our purposes, the large number of water pollutants can be usefully classified by

means of the taxonomy developed in Chapter 14.

Fund Pollutants. Fund pollutants are those for which the environment has some

assimilative capacity. If the absorptive capacity is high enough relative to the rate of

discharge, they may not accumulate at all. One type of fund water pollutant is

called degradable because it degrades, or breaks into its component parts, within the

water. Degradable wastes are normally organic residuals that are attacked and

broken down by bacteria in the stream.

The process by which organic wastes are broken down into component parts

consumes oxygen. The amount of oxygen consumed depends upon the magnitude

of the waste load. All of the higher life-forms in watercourses are aerobic; they

require oxygen for survival. As a stream’s oxygen levels fall, fish mortality increases,

with the less tolerant fish becoming the first to succumb. The oxygen level can

become low enough that even the aerobic bacteria die. When this happens, the

stream becomes anaerobic and the ecology changes drastically. This is an extremely

unpleasant circumstance because the stream takes on a dark hue, and the stream

water stinks!

To control these waste loads, two different types of monitoring are needed:

(1) monitoring the ambient conditions in the watercourse; and (2) monitoring the

magnitude of emissions or effluent as it is commonly labeled for water pollutants.

One measure commonly used to keep track of ambient conditions for these

conventional fund pollutants is dissolved oxygen (DO). The amount of dissolved

oxygen in a body of water is a function of ambient conditions, such as temperature,

stream flow, and the waste load.

The measure of the oxygen demand placed

on a stream by any particular volume of effluent is called the biochemical oxygen

demand (BOD).

Using modeling techniques, effluent (measured as BOD) at a certain point can

be translated into DO measures at various receptor locations along a stream. This

step is necessary in order to implement an ambient permit system or an ambient

emissions charge.

If we were to develop a profile of dissolved oxygen readings on a stream where

organic effluent is being discharged, that profile would typically exhibit one or

more minimum points called oxygen sags. These oxygen sags represent locations

along the stream where the dissolved oxygen content is lower than at other

points. An ambient permit or ambient charge system would be designed to reach

a desired DO level at those sag points, while a cap-and-trade or effluent charge

system would simply try to hit a particular BOD reduction target. The former

The danger of anaerobic conditions is highest in the late summer and early fall, when temperatures are

high and the stream flow is low.

477Nature of Water Pollution Problems

would take the location of the emitter into account, while the latter would not.

Later in this chapter we examine studies that model these systems on particular

watercourses.

A second type of fund pollutant, thermal pollution, is caused by the injection

of heat into a watercourse. Typically, thermal pollution is caused when an industrial

plant or electric utility uses surface water as a coolant, returning the heated water

to the watercourse. This heat is dissipated in the receiving waters by evaporation.

By raising the temperature of the water near the outfall, thermal pollution

lowers the dissolved oxygen content and can result in dramatic ecological changes

in that area.

Yet another example is provided by a class of pollutants, such as nitrogen and

phosphorus, that are plant nutrients. These pollutants stimulate the growth of

aquatic plant life, such as algae and water weeds. In excess, these plants can produce

odor, taste, and aesthetic problems. A lake with an excessive supply of nutrients is

called eutrophic.

The various types of fund pollutants could be ordered on a spectrum. On one

end of the spectrum would be pollutants for which the environment has a very large

absorptive capacity and on the other end pollutants for which the absorptive

capacity is virtually nil. The limiting case, with no absorptive capacity, are stock

pollutants.

Near the end of that spectrum is a class of inorganic synthetic chemicals called

persistent pollutants. These substances are called persistent because their complex

molecular structures are not effectively broken down in the stream. Some

degradation takes place, but so slowly that these pollutants can travel long distances

in water in a virtually unchanged form.

These persistent pollutants accumulate, not only in the watercourses, but also in

the food chain. The concentration levels in the tissues of living organisms rise with

the order of the species. Concentrations in lower life-forms such as plankton may

be relatively small, but because small fish eat a lot of plankton and do not excrete

the chemical, the concentrations in small fish would be higher. The magnification

continues as large fish consume small fish; concentration levels in the larger fish

would be even higher.

Because they accumulate in the food chains, persistent pollutants present an

interesting monitoring challenge. The traditional approach would involve

measurements of pollutant concentration in the water, but that is not the only

variable of interest. The damage is related not only to its concentration in the

water, but its concentration in the food chain as well. Although monitoring the

environmental effects of these pollutants may be more compelling than for other

pollutants, it is also more difficult.

Finally, infectious organisms such as bacteria and viruses can be carried into

surface water and groundwater by human and animal wastes and by wastes

from such industries as tanning and meatpacking. These live organisms may either

thrive and multiply in water or their population may decline over time, depending

upon how hospitable or hostile the watercourse is for continued growth.

478 Chapter 18 Water Pollution

DEBATE

18.1

http://www.cfsan.fda.gov/~dms/admehg3.html

Toxics in Fish Tissue: Do Fish Consumption

Advisories Change Behavior?

In January 2001, the Food and Drug Administration (FDA) released an advisory on

methyl mercury in fish. An updated advisory was issued in 2004 and again in

2006. Part of that advisory reads as follows:

However, nearly all fish and shellfish contain traces of mercury. For most people,

the risk from mercury by eating fish and shellfish is not a health concern. Yet,

some fish and shellfish contain higher levels of mercury that may harm an un-

born baby or young child’s developing nervous system. The risks from mercury in

fish and shellfish depend on the amount of fish and shellfish eaten and the levels

of mercury in the fish and shellfish. Therefore, the Food and Drug Administration

(FDA) and the Environmental Protection Agency (EPA) are advising women who

may become pregnant, pregnant women, nursing mothers, and young children

to avoid some types of fish and eat fish and shellfish that are lower in mercury.

The FDA targeted women planning on becoming pregnant within six months,

pregnant women, and nursing women to receive information about the new

advisory on methyl mercury.

Since mercury persists and bioaccumulates, the concentrations of mercury

rise as you move up the food chain. Ingested mercury has been linked to neuro-

logical disorders in infants and children. Using the Bureau of Labor Statistics’

Consumer Expenditure Survey, Shimshack, Ward, and Beatty (2007) examine the

effectiveness of advisories in affecting consumer choices. In particular, they look

at the effects of the advisory on the consumption of canned fish during

1999–2002, a time period that includes two years before and two years after the

advisory. They examine whether the groups targeted reduced their consumption

of canned fish and what determined the responses.

Comparing target households (those with young children) to nontarget

households, they find that targeted consumers significantly reduced their canned

fish consumption as a result of the warning. College-educated consumers

responded quite strongly. Additionally, they found that newspaper and magazine

readership were significant in influencing the post-advisory reduction in fish

consumption, but health consciousness was not. Interestingly, they also found

evidence of spillover effects; nontargeted consumers also reduced their

consumption of canned fish.

Access to information is clearly important to the success of a health advisory.

At-risk consumers who were less educated and nonreaders did not significantly

reduce consumption. The authors suggest that this particular group is also less

likely to be able to withstand negative health shocks.

What is the best way to get information to different population groups?

Unequal access to information creates unevenly distributed health risks and

might be labeled an environmental justice issue.

Sources:

Jay P. Shimshack, Michael B. Ward, and Timothy K.M. Beatty. “Mercury Advisories: Information,

Education and Fish Consumption,”

Journal of Environmental Economics and Management

Vol. 53, No. 2

(2007): 158–179; www.fda.gov.

479Traditional Water Pollution Control Policy

Stock Pollutants. The most troublesome cases of pollution result from stock

pollutants, which merely accumulate in the environment. No natural process

removes or transforms stock pollutants; the watercourse cannot cleanse itself

of them.

Inorganic chemicals and minerals comprise the main examples of stock

pollutants. Perhaps the most notorious members of this group are the heavy

metals, such as lead, cadmium, and mercury. Extreme examples of poisoning by

these metals have occurred in Japan. One ocean-dumping case was responsible

for Minamata disease, named for the location where it occurred. Some 52 people

died and 150 others suffered serious brain and nerve damage. Scientists puzzled

for years over the source of the ailments until tracing it to an organic form

of mercury that had accumulated in the tissues of fish eaten three times a day by

local residents.

In the United States, mercury contamination of fish has led to consumption

advisories for many freshwater and migratory fish. Women of childbearing age

and children especially are cautioned against eating large amounts of certain

species. Debate 18.1 examines the effects of fish consumption advisories on

consumer behavior.

In another case, in Japan, known as the itai itai (literally, ouch-ouch) disease,

scientists traced the source of a previously undiagnosed, extremely painful

bone disease to the ingestion of cadmium. Nearby mines were the source of

the cadmium, which apparently was ingested by eating contaminated rice and

soybeans.

Most recently, medicinal waste has been found in watercourses and in fish

tissue. In 2002, the USGS tested 139 rivers in 30 states and found that 80 percent

of the streams sampled resulted in evidence of residuals from drugs such as

birth-control pills and antidepressants. Residuals from soaps, perfumes, and

caffeine were also found. While the magnitude of the damage that will ultimately

be caused by these substances is not yet clear, it is certainly a new twist in water

pollution control policy.

As is typical with persistent pollutants, some of the stock pollutants are

difficult to monitor. Those accumulated in the food chains give rise to the same

problem as is presented by persistent pollutants. Ambient sampling must

be supplemented by sampling tissues from members of the food chain. To

further complicate matters, the heavy metals may sink rapidly to the bottom,

remaining in the sediment. While these could be detected in sediment samples,

merely drawing samples from the water itself would allow these pollutants to

escape detection.

Traditional Water Pollution Control Policy

Water pollution control policies vary around the world. In this section we begin

with a somewhat detailed discussion of U.S. policy, which provides a rather rich

example of a typical legal approach to regulation. This is followed by a discussion of

the European approach, which has depended more heavily on economic incentives.

480 Chapter 18 Water Pollution

U.S. policy for water pollution control predates federal air pollution control. We

might suppose that the policy for water pollution control would, therefore, be superior,

since authorities had more time to profit from early mistakes. Unfortunately, that is

not the case.

Early Legislation

The first federal legislation dealing with discharge into the nation’s waterways

occurred when Congress passed the 1899 Refuse Act. Designed primarily to

protect navigation, this act focused on preventing any discharge that would

interfere with using rivers as transport links. All discharges into a river were

prohibited unless approved by a permit from the Chief of the U.S. Engineers. Most

permits were issued to contractors dredging the rivers, and they dealt mainly with

the disposal of the removed material. This act was virtually unenforced for other

pollutants until 1970, when this permit program was rediscovered and used briefly

(with little success) as the basis for federal enforcement actions.

The Water Pollution Control Act of 1948 represented the first attempt by the

federal government to exercise some direct influence over what previously had been

a state and local function. A hesitant move, since it reaffirmed that the primary

responsibility for water pollution control rested with the states, it did initiate the

authority of the federal government to conduct investigations, research, and surveys.

Early hints of the current approach are found in the amendments to the Water

Pollution Control Act, which were passed in 1956. Two provisions of this Act

were especially important: (1) federal financial support for the construction of

waste treatment plants and (2) direct federal regulation of waste discharges via a

mechanism known as the enforcement conference.

The first of these provisions envisioned a control strategy based on subsidizing

the construction of a particular control activity—waste treatment plants.

Municipalities could receive federal grants to cover up to 55 percent of the con-

struction of municipal sewage treatment plants. This approach not only lowered

the cost to the local governments of constructing these facilities, but also it lowered

the cost to users. Since the federal government contribution was a grant, rather

than a loan, the fees users were charged did not reflect the federally subsidized

construction portion of the cost. The user fees were set at a lower rate that was

high enough to cover merely the unsubsidized portion of construction cost, as well

as operating and maintenance cost.

The 1956 amendments envisioned a relatively narrow federal role in the regula-

tion of discharges. Initially, only polluters contributing to interstate pollution were

included, but subsequent laws have broadened the coverage. By 1961, discharges

into all navigable water were covered.

The mechanism created by the amendments of 1956 to enforce the regulation of

discharges was the enforcement conference. Under this approach, the designated

federal control authority could call for a conference to deal with any interstate

water pollution problem, or it could be requested to do so by the governor of an

affected state. The fact that this authority was discretionary and not mandatory and

that the control authority had very few means of enforcing any decisions reached

meant that the conferences simply did not achieve the intended results.

Tietenberg Tom, Lewis Lynne. Environmental &amp; Natural Resource Economics

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Tietenberg Tom, Lewis Lynne. Environmental & Natural Resource Economics