Transcript California Water Issues AGST 3000 Agriculture, Society and the Natural World “Whiskey’s for drinkin’ and water’s for fighting for….” Mark Twain.

California Water Issues
AGST 3000
Agriculture, Society and the Natural
World
“Whiskey’s for drinkin’ and water’s for
fighting for….”
Mark Twain
California’s Major Water Users:
– irrigated farm land, a huge
economic engine for the state.
 Environment – fish and other wild life have
specific water requirements.
 Families – human factor, showers, dishes,
swimming pools and golf courses.
 Manufacturing – processing, cooling
produce jobs for the state which generate
a tax base.
 Agriculture
Water Terminology
Acre-foot
An acre-foot equals the amount of water needed
to cover an acre of land to the depth of one foot
(326,000 gallons) and is approximately the
amount of water used by an average family of
four during one year.
Overdraft
The deficit between pumped water from a
groundwater basin and the long-term recharge.
California’s Tug of Water
Geologic Tugs
Geologic Tug #1: The North 75%– 25% South
precipitation distribution circumstance
Geologic Tug #2: The Coast Range and Sierra Nevada
Mountains rain shadow effects
Geologic Tug #3: The Drought/Flood cycles – El Nino and
La Nina
Geologic Tug #4: Calif. is the number 1 ground water
using state, but has little regulation
California’s Tug of Water
Water Use Tugs
Water Use Tug #1: 80% of water demand occurs south
of Sacramento North versus South
Water Use Tug #2: There is also an East versus West
use conflict
Water Use Tug #3: Water demand is highest in the
summer when availability is lowest
Water Use Tug #4: Environmental water use conflicts
with agriculture, urban need.
Water Use Tug #5: Agriculture versus Urban use: who
gets how much and when, etc.?
Water Use Tug #6: What are the water rights for
various interest groups in the future?
Figure 1. Freshwater Consumption as a Percentage of Local
Average Annual Precipitation. (Source: USDA-NRCS, 2001)
California’s Water Supply
California’s ground water

California’s groundwater basins store about 850 million
acre-feet of water. (Less than 50% is unavailable for use
due to depth of water table.)

For long term sustainability, groundwater cannot be
removed that will not be replenished.

15 million acre-feet of groundwater is pumped each year.
 20% of the state’s water requirements are met with
pumped groundwater.

CA is operating on a 1.3 million acre-foot overdraft.

CA groundwater is recharged by:



1) Nature – rain & snow (7 million acre-foot annually)
2) After usage – agriculture & industry (6.65 million acre-feet /yr.)
3) Recharge programs – Los Angeles municipal water
California’s surface water

Comes from an average annual statewide
precipitation of almost 24 inches. (Ranging from
almost nothing in the deserts to more than 100 inches in the
northern mountains)

Sixty percent of the precipitation is evaporated
or transpired by trees and vegetation.


The remaining forty percent equals about 71 million
acre-feet of stream flow (in an average rainfall year).
Colorado River flows diverted to California
supply 4.8 million acre-feet.
California’s surface water continued…

Inflow streams from Oregon add an addition 1.4
million acre-feet.

This means in an average year California has
available slightly more than 78 million acre-feet
of water.

However, not all of this water can be collected
for use (almost 29 million acre-feet occurs in the north coast
region alone and much of it is unavailable for use).
Agriculture’s Water Use:

80% of developed supply (reservoir storage,
irrigation districts, state and federal water projects)

28-35 million acre-feet depending on yearly rainfall

Irrigated acres 2002-8,709,353

Irrigated acreage is declining due to urban growth
and water cut backs by federal/state projects.

A large percentage of agriculture water percolates
back into ground or streams (around 5 million acre-feet
contributes to re-charge)
1997-8,886,693
Urban and Environmental Water Use

CA urban use is about 7.8 million acre-feet.


One acre of houses uses approximately the same
amount of water as an acre of agriculture crops
(what happens to this water?)
26 million acre-feet is diverted to environmental
uses during normal years less in drought years)
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9.56 million acre-feet for the Delta
17.8 for wild and scenic river flows
This amount is expected to increase
Regional Water Use

Central Valley

Sacramento River 11.7 million acre-feet

South Coast
4.6 million acre-feet

Colorado River
4 million acre-feet
19 million acre-feet
Groundwater supply initially huge

Maybe as much as 750,000,000 acre feet
accumulated over thousands of years

Efficient pumps developed around 1920

Irrigated acreage rapidly expanded several fold


Groundwater levels began to drop precipitously
“subsidence” ground is actually sinking.
IRRIGATION
A. Definition: Supplying water to plants in an
artificial manner. (39% of all freshwater in
the US is used to irrigate crops)
1. Ancient practice – first irrigation used
ditches to divert rivers and streams.
2. California agriculture relies on irrigation.
a. Mediterranean climate
b. Crop diversification
c. Economics
Population Water Needs
According to U.S. Census Bureau figures,
California’s population currently is 35.1 million,
and is projected to hit 49.3 million by 2025.
1998 California Water Plan update: the state
Department of Water Resources (DWR) forecast
a gap between water supply and demand
ranging from 2.4 million acre-feet during normal
years up to 6.2 million acre-feet in drought years
by 2020.
The next water plan is due in 2003
An acre-foot =
An acre-foot of water is about 326,000
gallons –
enough to cover an acre of land, about the
size of a football field, 1 foot deep and
meet the average needs of between one
and two residential households
Sources of Water
 Rain
and Snow replenishes the surface
water and underground aquifers
 Ground
Water (aquifers)
 Surface
Water (rivers, lakes, reservoirs)
Sources of Surface Water
California, there are two major arteries
serving as the sources of surface water for
urban and agricultural areas:
 The
Sacramento-San Joaquin Delta (BayDelta) and

The Colorado River
The Delta
 Delta
serves as a major water source for
approximately two-thirds of the state –
over 22 million people
 The
region is fed by two major rivers: the
Sacramento from the north and the San
Joaquin from the south
The Delta

Mixture of fresh water from these two waterways and
numerous tributaries combine with salty ocean water
from San Francisco Bay to create the largest estuary
on the West Coast of North America - The San
Joaquin Delta.

Massive pumps at the southern end of this marsh
pull approximately 5.5 million acre-feet annually of
fresh water southward to Central Valley farmland via
the Central Valley Project and ultimately, to the
southern California region via the State Water
Project.
Federal Central Valley Project

FDR and U.S. Reclamation Service looking for
projects, took over CVP in 1935, began construction
in 1937

Eventually completed in 1950’s
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Final cost more than $500 million
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Distributes more than 3,000,000 acre feet of water

Almost all used for agriculture

No connections to Southern California initially
The Colorado River

Colorado River winds its way through the southwestern
United States before terminating in the Gulf of California in
Mexico.

Provides water to seven states including California, with each
state's water use determined by the Colorado River Compact
of 1922.

California permitted to use 4.4 million acre-feet annually.

For over a decade, California has been using well beyond the
1922 allotment.

As water conditions have tightened in several of the other
states, the secretary of the Interior has demanded that
California reduce its use of the Colorado River - a major
challenge to river water users.
Basic Types of Irrigation
Flood – Explain
used in almonds, peaches, walnuts, rice, alfalfa
Flood in the West, Border in the East
Flood Irrigation continued…
Advantages:
• inexpensive
• less labor
• large amounts of water leach
salts
• rodent control
Flood Irrigation continued…
Disadvantages:
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land must be leveled or contoured
uses large amounts of water
water loss through evaporation
may cause disease in some crops if applied
incorrectly
run off water can cause problems (silt buildup
in rivers, may contain pesticides)
Furrow Irrigation
Used in row crops such as beans, tomatoes,
corn, sugar beets other vegetable crops.
Similar advantages and disadvantages
to flood irrigation.
Furrow Irrigation
Sprinkler Irrigation
Many types micro-sprinklers, solid set, aluminum
pipe
a. Advantages: use less water, more precise
amounts of water can be applied, less run off
(tail water), may be used on slightly hilly land
b. Disadvantages: expensive (installation,
labor, filters, maintenance), salt buildup
 Better
spray
version of center
pivot for water
conservaton
Drip Irrigation
Used on specific crops, such as grapes, trees
(such as almonds, cherries, peaches)
a. Advantages:

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uses less water
very precise amounts as well as fertilizer
b. Disadvantages:

expensive to install, (labor, equipment,
maintenance)
Drip Irrigation
Subsurface Irrigation
Questions on Irrigation:
1. Where does irrigation water come
from?
a. Wells – underground aquifers
b. River – “Riparian rights” or water
rights
c. Irrigation Districts – provide water
from large water sources, lakes,
reservoirs (dams)
What are concerns people have over the use of
irrigation in agriculture?
a. Overdraft of underground water supplies
(aquifers).
b. Water pollution – silt, herbicides, pesticides
added to irrigation water runs off into lakes,
rivers, etc.
c. Concerns over water waste – flood irrigation
uses a lot of water
d. Production of crops in California that are not
water efficient – alfalfa and cotton.
How has agriculture addressed the public’s
concerns over water usage?
a. The #1 water user in California is
___________________________.
(set the record straight)
*California and Texas are the only 2 states that
do not have regulations on groundwater
pumping.
Water Problems
Erosion
Pollution
Waste
Erosion
 Power
of a droplet of water striking the soil
surface
 Moves
tons of soil
 Runs
off to rivers and streams (siltation)
 Tons
of soil lost
Pollution
What types of water pollution?
 Underground
water supplies…
 Surface
runoff (erosion and contamination
from crop and animal activities)
 Soil


water (salts)
Pre-ag existance
Ag production induced
Water Pollution Mitigation
A
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couple of Answers
Total containment of runoff or drainage from
intensive animal facilities…lagoons
soil polymers – adhere to water particles
preventing their runoff
use of IPM and GMO’s (reduce the need for
chemicals)
Water Waste
Caused by evaporation, infiltration, runoff
Flood irrigation is the largest waste of water
Drip and micro sprinkler use
Cost/economics – as the price of water
increases, farmers can afford to use less
and must become more efficient.
Economics Driven Politics
For specific types of Agriculture production…
Special Treatment, Government Subsidies and
Corporate Welfare
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Water Projects
Non-point source pollution in the past
Subsidies from government that encourage
production of high water use commodities
(Cotton and Milk)