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OCR for page 49
3
WHAT ARE ACCEPTABLE RISKS FOR PUBLIC SYSTEMS?
Duane L. Georgeson
Los Angeles Department of Water and Power
Los Angeles, California
The subject of drought management in the context of
risk assessment is a relatively new concept in terms of
urban water supply planning. Simply stated, the concept
of drought management would be to plan for a water
supply that would be available at all times except
during droughts with some calculated recurrence
interval, say once in 50 years or once In
_ . . . . ~
~ _
100 years.
Determining an appropriate drought recurrence interval
for water supply planning is extremely difficult due to
the highly unpredictable nature of droughts. This
discussion briefly describes some of the problems
associated with this type of risk analysis and examines
some practical drought management strategies in the
context of past experiences and necessary future
planning.
FLOOD MANAGEMENT PLANNING
Although risk assessment has been applied to flood
damage mitigation for many years, there is-no simple
formula, such as one percent chance of exceedence, that
can be applied to all situations. The planning of flood
mitigation facilities is far more complex and rightly so.
For example, along California's largest intrastate
river, the Sacramento, some agricultural lands are
inundated every two or three years by flood waters that
overflow at seven control structures, ~
cost of flood control along the river
the Sacramento-San Joaquin Delta area
below-sea-level islands protected by
delta islands, composed of primarily agricultural lands
with some urban development, experience flood perhaps
thus reducing the
There is also in
a complex of
levees. These
-49-
OCR for page 50
-50-
every 20 years. Although most urban flood control
facilities are designed to accommodate a 100-year flood,
certain other structures, such as dam embankments and
spillways, are often designed to safely pass the
probable maximum flood that approximates a 1000-vear
recurrence interval. Because of the potential of
catastrophic loss of life and property damage associated
with dam failure, particularly in urban areas, public
policy dictates that special consideration be given to
the construction of dams.
Similarly, no set recurrence level can be used for
. · .
trough planning. the ~mposs'n~l~ty at predicting bow
and when a drought will unfold and the problems of
applying uniform measures to deal with the drought make
risk assessment very difficult.
During drought periods, various management strategies
have been employed to allocate an inadequate water
supply among competing users for that supply.
AGRICULTURAL DROUGHT MANAGEMENT
One example of drought management applied to
agricultural water users is the U.S. Bureau of
Reclamation's Central Valley Project in California,
which serves almost 3 million acres of land. The
Central Valley Project has "firm" water or Class 1 water
available in most years, and in addition has Class 2
water that is available on a "less firm" basis. In dry
years, when little or no Class 2 water is available, the
farmers have the option of reducing their irrigated
acreage of annual crops or increasing their production
from alternative supplies such as individual wells.
The Bureau's system. in eeneral. works well: however
the example above does not fit the typical urban
situation, since most urban water users neither make an
explicit annual decision on their needs for domestic
water or water-using vegetation nor do they have the
option of turning to individual wells. Also, while a
contract system might work fine for a few hundred to a
few thousand agricultural water users, it has some
obvious limitations for an urban setting with hundreds
of thousands of small customers.
OCR for page 51
-51-
THE GREAT CALIFORNIA DROUGHT OF 1976-1977
From November 1975 through November 1977, California
experienced its most severe drought of this century.
Although most of the urban and farming areas are
accustomed to the almost total absence of precipitation
during the growing season from April through October, in
1976 and 1977 the winter periods experienced only
one-half and one-third of normal precipitation,
respectively. The result was California's fourth driest
and driest years of record, successively. Most surface
storage reservoirs were substantially drained in 1976,
with the result that there were widespread shortages
when 1977 turned out to be even drier.
Many dramatic and imaginative programs were
implemented by federal, state, and local officials, as
well as private companies, farmers, and individuals to
cope with the water shortage. In general, the public
response and cooperation were outstanding because the
evidence of shortage was clear and
uncontrovertible--bare ski slopes in the winter and
empty lakes and reservoirs in the summer. Southern
California with its access to the giant Colorado River
reservoirs at Lake Mead and Lake Powell was less hard
hit than the normally wetter areas of Central and
Northern California (interestingly, the Colorado River
also experienced its driest year in recorded history in
1977~. As a result, Southern California was able to
give up substantial quantities of its contracted rights
to water from the State Water Project to assist the San
Francisco Bay area (approximately 40 billion gallons)
and the San Joaquin Valley farmers (approximately 100
billion gallons).
The cost of the two-year drought has been estimated at
$2.5 billion, with those hardest hit economically being
businesses directly dependent on precipitation--cattle
ranches and recreational facilities, particularly ski
resorts. Also hard hit was hydroelectric generation in
Northern California (only 38 percent of normal), with
replacement made up at much higher cost from burning
increased quantities of fossil fuels at Southern
California plants for export to Northern California.
The impact on farm production, other than range cattle,
was substantially lessened by the increased use of
ground water with accompanying higher costs. It has
been estimated that up to 10,000 new wells were drilled
or deepened to provide replacement agricultural water.
,
.
OCR for page 52
-52-
(See Table 3-1 for a comparison of agricultural
production in 1977 with the previous three years.)
Much media attention was received by the urban water
conservation programs in California during the drought,
and in particular, the programs in Marin County, where,
due to a particularly severe supply deficiency, water
use was reduced by approximately 65 percent to only 45
gallons per person per day. However, other urban water
customers throughout California also enthusiastically
cut their water use as can be seen on Table 3-2. Public
opinion polls in water-short areas during 1977
determined that city dwellers had substantial sympathy
for the plight of the farmers and frequently stated the
opinion that the urban water user could more easily
conserve than the farmers.
TABLE 3-1 Agricultural Response to Drought
Field Fruit- and Nut- Vegetables
Year Crops Bearing Crops and Melons Total -
.
Acreage
1974 6,520,300 1,508,010 861,320 8,889,630
1975 6,602,000 1,571,440 921,660 9,095,100
1976 6,590,000 1,634,540 829,466 9,054,006
1977 6,359,000 1,673,890 914,652 8,947,542
Production (tons)
24,986,000 8,702,700 11,820,750 45,509,450
28,566,000 9,794,800 13,312,050 51,672,850
28,965,000 9,626,600 11,051,650 49,643,250
25,009,000 9,673,700 13,037,750 47,720,450
This table displays the harvested acreage and production
of the principal crop groups in California during the
drought of 1976-1977 as compared with the two previous
years. These figures include both irrigated and dry
farm acreage and production. As indicated, acreage and
production actually increased in the drought year 1977
for fruit- and nut-bearing crops, vegetables, and melons
SOURCE: From The California Water Atlas (1978~.
OCR for page 53
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OCR for page 54
—54—
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OCR for page 55
-55-
DEVELOPMENTS SINCE 1977
Because of the dramatic urban water conservation
achievements during the drought there was, during 1977,
substantial debate regarding whether the per capita
water use assumptions for water planning should be
substantially reduced to reflect an enlightened new
"urban water ethic." Unfortunately, water use habits of
Californians, from both the north and south, have proved
difficult to modify. Table 3-3 shows that per capita
water use has returned to near predrought levels in most
cities, even though many cities continue with water
conservation programs.
A recent news article reported that even though water
use in Marin County had returned to predrought levels,
the public perception was that they were still
conserving. In one survey, 45 percent of the people
responded that they were already doing all that they
could do to conserve. Another survey in California
determined that 80 percent of respondents felt that
substantial water could be conserved, but only 30
percent believed that they personally could conserve
water.
Another interesting development relates to the
public's growing recognition that 85 percent of the
agriculture and
that less than 15 percent is used for all urban
purposes. Much attention has focused on the alleged
waste of water bY the Imnerial Irritation District. the
water used in California is used for
~ . ~
largest agricultural district in California. As a
result of continuing pressure, preliminary approval has
been given to a plan to conserve 100,000 acre feet per
year (approximately 90 million gallons per day) by
lining canals and reducing water losses. The conserved
water would be made available to urban Southern
California, which would reimburse Imperial $10 million
annually to develop the conservation programs. This
proposed transaction has stimulated a growing debate
regarding the need for developing a "free market" to
permit water to be sold to the highest bidder, just as
any other commodity.
WATER PLANNING IN CALIFORNIA
Most urban areas of California, whether the San
Francisco Bay area or Los Angeles or San Diego, depend
OCR for page 56
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OCR for page 57
-57-
for most of their water on long aqueducts from either
the Sierra Nevada, the Sacramento Delta, or the Colorado
River. In addition, there are 9 million acres of
irrigated lands that are also supported by similar
aqueduct systems moving water great distances (see
Figure 3-1~.
The management of California water systems involves
all levels of government--federal, state, 20 different
special districts, counties, cities, the other six
states of the Colorado Basin, and even Mexico. The
abundance of water in the rural north and the need for
water in the more arid areas from San Francisco south
gives most major water planning activities a statewide
character. For that reason, the state legislature has
been the focal point of three me jar efforts in the last
eight years to develop a statewide program to complete
the State Water Project, which voters approved narrowly
in 1960 and which today can meet only one-half of its
contractual commitments. Although one of these
legislative proposals was approved by 60 percent of the
legislators in 1980, it was subsequently repealed in a
statewide referendum, which 6~0 percent of southern-
voters approved but which 90 percent of northerners
rejected.
The extreme difficulty of achieving a statewide
consensus on water development in the face of continued
population and economic growth, together with the future
loss to Arizona of more water than is used by the City
of Los Angeles, raises the specter of more frequent
drought shortages in the years ahead. There is little
question that all aspects of drought management will get
increasing attention from water professionals,
environmental organizations, and government leaders, but
how the decision-making will take place is difficult to
forecast.
POTENTIAL CONSEQUENCE S OF URBAN WATER SHORTAGE S
Serious consideration needs to be given to the
potential magnitude of the urban water shortage in order
to consider which decision-makers should be involved in
deciding what constitutes acceptable risk for
shortages. For example, if the shortage is to be one of
limited duration or severity that can be accommodated by
short-ter~ conservation programs (such as odd and even
days for lawn watering), perhaps such decisions could be
OCR for page 58
—58—
SHASTA (USBR)
......
·..l,
. .
: :
i,` ~ " " i._-_ ~ A.
·.l'. {''''"
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. ; w
r~S,~,~'''
;_-— , ~ ~LU~NE (E.~.~.U.De)
_\~HETCH HETCHY (8.F.)
SAN FRANCISCO ~
it:
,~`DELYA-~ENDOTi`(U4R.)
~ jRIAN4KERN 4.R.)
CALIF. A.....
....... ......
_' .
~--~-~-
:-
~ os A~
FIGURE 3-1 California water transfer facilities.
\LOS ANGE4. (L.~.)
.. .... \.
,,_ .1 I_ —-
·:--.~ 1
A\ . t ~
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.. _ .
OCR for page 59
-59-
made by the local water utility board. On the other
hand, if the potential water shortage would necessitate
"Hong Kong" type rationing, where the public water
supply system would operate only a few hours per day to
conserve a very limited resource, the decisions should
be made by general government and elected officials,
since important public safety considerations are
involved. (Profound impacts on the public include
diminished fire protection and greater contamination
threats because of backflow potential into unpressurized
water mains.) Even if the potential water shortage is
well short of a "Hong Kong" type of shortage, local
government should almost certainly be involved in the
planning stages, since many of the drought management
options require the leadership of top elected officials
to convince the public of their necessity. Other
options require the exercise of police powers, which are
available to local general government, but which are
usually not available to the local water utility board.
URBAN AND AGRICULTURAL COMPETITION AND COOPERATION
Following the drought of 1977, there developed some
support for the notion that urban water users are more
able to conserve than farmers and perhaps contractual
provisions which require agriculture to take the first
shortages should be reversed to require urban users to
accept initial shortages.
As discussed above, urban users developed substantial
sympathy for water-short farmers during the 1977
drought. Whether this sympathy would have continued
into 1978, if it had been a third dry year, is very
uncertain particularly if urban users had become
generally aware that total irrigated acreage slipped
very little in 1977 and that productivity actually
increased in several major areas (see Table 3-1~.
In normal water supply years, over 10 million acre
feet per year of water is used to irrigate alfalfa and
cotton. Some critics of California water development
have suggested that, since these crops have a gross
value of only about $1 billion per year or about $100
per acre foot, during drought periods alfalfa and cotton
production could be curtailed to provide water (at a
profit to the alfalfa and cotton farmers) for urban
users and higher valued agricultural commodities. These
simplistic proposals, however, fail to consider that
OCR for page 60
-60-
while such financial transactions might be very
appealing, they do not usually suggest any form of
compensation to third parties such as farm workers, crop
dusters, farm equipment dealers, and the myriad other
support businesses and employees. Even local
governments have their concerns because of potentially
reduced tax levies and increased welfare costs e
A more likely, near-term, scenario of urban and
agricultural cooperation would be expansion of the
above-mentioned pending transaction between the Imperial
Valley and the Metropolitan Water District of Southern
California. The concept of using urban dollars to
increase the efficiency of agricultural water use while
maintaining farm production provides a win-win-win
solution including benefits, not detriments to virtually
all third parties including workers, support businesses,
and even local tax collectors.
PUBLIC COMMITMENT
As discussed, the success that urban areas in
California achieved in reducing water use (see Table
3-2) has lead to speculation that sharp reductions in
urban use could be easily achieved again in the future.
Water planners and those involved in public policy
development in this area should keep in mind that
mandatory conservation and rationing programs lasted a
relatively short time. By early November 1977, when
heavy statewide precipitation mercifully arrived, most
urban water customers and public officials were growing
weary of the problems and nuisances of living with the
water shortage. For example, in the City of Los
Angeles, which had implemented water rationing for the
first time in the 75-year history of the municipal water
system, 85 percent of the water customers were meeting
their water conservation goals; however, this still left
approximately 100,000 different residential, commercial,
and industrial customers who were in violation. Under
the City's Emergency Water Conservation Plan (see
Appendix A), these 100,000 customers were scheduled to
have flow restrictors installed on their service lines
during November and December of 1977 at a minimum charge
of $25 per customer. The logistics of such an effort
and the enormous customer relations problem associated
with it would almost certainly have forced the Los
Angeles City Council to modify this portion of the
OCR for page 61
-61-
emergency plan, and of course any weakening of the plan
would bring loud complaints from the 85 percent of the
customers who were, at some expense and inconvenience,
meeting the plan's requirements. The experiences with
emergency water ordinances in Marin County, San
Francisco, and dozens of other California communities
were very similar to that being experienced in Los
Angeles. One can only speculate on the political,
administrative' legal, and other problems that would
have resulted if the drought had extended through 1978.
As discussed above, it is very likely that the
continuing high rate of agricultural water use in
California would eventually have come to the attention
of urban areas and very likely undermined the enthusiasm
of urban areas for maintaining the increasingly less
popular restrictions.
The success of urban water conservation in 1977 was
undoubtedly due to the public recognition of a real and
widespread problem and the perception that water
restrictions and penalties were being fairly
administered. Public commitment to water conservation
would likely erode quickly if financial penalties and
other restrictions were perceived as not being
enforced. For example, water agencies in New Jersey
experienced substantial public backlash a few years ago
when financial penalties imposed during the drought on a
number of large customers were waived upon easing of the
drought.
WATER AGENCY RESPONSIBILITY
If the public feels that water agencies are managing
water supplies responsibly and efficiently, they will be
more likely to support proposed conservation measures in
emergency situations. The ability to extend supplies
during water-short periods is important to public
confidence.
One important way to extend water supplies and
increase flexibility during emergency situations is
through the increased use of ground-water storage
basins. Additional wells and distribution lines can be
constructed to give greater ability to pump ground water
when other sources grow scarce. Conversely, pumping can
be curtailed in wet periods and recharge programs can be
expanded to ensure that basins will be adequately full
to handle emergency situations.
OCR for page 62
-62-
FINANCIAL AND INSTIfUTIONAL PROBLEMS
In California, with its multitude of different levels
of water agencies, there are major legal and contractual
problems associated with drought management planning.
In Southern California, there is a large wholesale water
agency,
California (MWD), which provides supplemental water to
Los Angeles, San Diego, and 24 other cities and water
district. ~ The MW1) Ant nr~vi H~.c ~ ' ~ ~ '
the Metropolitan Water District of Southern
r ~ —~ ~
_ _ _
~ r~~~~~~~ Gnat each member agency
has a preferential right to purchase water based on the
proportion of property taxes paid by each member
agency. When the 1977 drought occurred, the City of Los
Angeles had a preferential right to 30 percent of the
MWD supply, and San Diego County had a right to 10
percent of that supply. (Normally, Los Angeles uses
only 2 percent of the supply, and San Diego uses 25
percent.) However, during 1977 for a variety of
complicated legal and political reasons, the City of Los
Angeles imposed water rationing and was able to limit
its use of MWD water to approximately 7 percent of the
HWD supply, or one-fourth of its legal right, whereas
San Diego did not impose rationing and purchased 27
percent of the MWD supply or almost 3 times its legal
right. There is no suggestion of impropriety on San
Diego's part intended by these remarks, merely a
statement of what took place during the 1977 drought.
It is likely that the events of 1977 would receive
considerable attention when a water shortage within the
MWD service area occurs at some future time.
This issue remains a matter of considerable interest
in both Los Angeles and San Diego, since Los Angeles
continues to pay property taxes that are approximately
$19 million per year, and San Diego only pays $10
million. There is also extensive debate with MWD at the
present time as to whether the entire preferential right
concept should be modified or abolished, given the fact
that preferential rights have never been used to
allocate water during a time of shortage.
Solutions with acceptable public risks for drought
management are elusive. The above example has been
debated for more than two decades. The hundreds of
other water agencies throughout California have
institutional and financial relationships of similar
complexity.
v - - —
. . —
OCR for page 63
-63-
DROUGHT MANAGEMENT DECISION-MAKING
Since the consequences of urban water shortages are
potentially very serious and involve great numbers of
people, the decision-making unquestionably must take
place by the elected officials. Given the great
uncertainty about the timing or severity of future
droughts, water officials are understandably reluctant
to "cry wolf" and urge elected officials to immediately
begin development of what would have to be fairly
complicated water curtailment ordinances. There is a
concern that pressure by the water managers for such
ordinances would be perceived as merely a poorly
disguised "hype" for additional expensive water projects.
In the case of the City of Los Angeles, there is an
existing Emergency Water Conservation Ordinance (see
Aonendix A), which was hastily developed during the
spring of 1977 to deal with the water shortage of that
time. Although the ordinance is far from perfect, it at
least provides a standby mechanism that could be
triggered in the event of some future water shortage and
perhaps fine-tuned on rather short notice.
Other cities and counties that do not currently have
in place such ordinances will probably do as Los Angeles
did, namely, wait to implement such a plan until
conditions demand such action.
Leaving the development of water curtailment
ordinances to over 100 cities and counties in Southern
California is clearly a fragmented approach to dealing
with a regional problem; however, since the regional
agency, MOOD, is a special district without the police
powers of general purpose government, it is difficult to
conceive how regional water curtailment plans could be
implemented even in the presence of a severe drought.
The same is true for a statewide water curtailment
program. Although the state legislature has adequate
police power, the water supply issues become almost
hopelessly complicated with thousands of different water
purveyors with vastly different circumstances and
involving both agriculture and urban water supplies.
CONCLUDING REMARKS
The experience of the 1976-1977 drought in California
demonstrated that, at least over a limited period of
approximately 6 months, urban areas are capable of
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achieving imaginative and substantial reduction in water
use. It is far from clear how the achievements of 1977
can be translated into some rational quantitative risk
management approach to water supply planning, given the
impossibility of predicting when and how future droughts
will unfold. Perhaps, the best that can be achieved is
for the water managers to be familiar with the variety
of strategies that succeeded and those that failed for
implementation of appropriate ones on an ad hoc basis
during future water shortages. As crises occur, drought
management will continue to improve as we build upon
past experiences.
California in 1985 is experiencing a year almost as
dry as 1976. The hot, dry weather is causing reservoir
levels to drop sharply throughout the state (with the
exception of the Colorado River, which this year is
above normal) causing farmers and city dwellers to
wonder whether 1986 will bring the repeat of 1976-1977
drought. Perhaps by September 1986, California will
have some new chapters to add to our drought contingency
plans and perhaps the subject-of drought management will
be receiving even greater attention than it is today.
REFERENCE
Governor's Office of Planning and Research in
Cooperation with the California Department of Water
Resources. 1978. The California Water Atlas.
Sacramento, California.
Representative terms from entire chapter:
drought management
