Transcript Water and Irrigation Read “From Farms to Floodplains & Filtration Systems” …in class writing assignment Read “Irrigation Drainwater Contamination in the San Joaquin Valley”…Journal Writing Assignment AGST.

Water and
Irrigation
Read “From Farms to Floodplains & Filtration
Systems”
…in class writing assignment
Read “Irrigation Drainwater Contamination in the
San Joaquin Valley”…Journal Writing Assignment
AGST 3000
Agriculture, Society and the Natural World
Irrigation
"Whiskey's for drinking; water's for fighting over" –
Cities, farmers and environmentalists have battled
over who will control California's water forever
Why? Our Valley Climate!
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Irrigated surface water scarce in spite of flooding
Extended summer drought
Southern and western portions quite dry
Groundwater supply initially huge

Maybe as much as 750,000,000 acre feet
accumulated over thousands of years

Efficient pumps developed around 1920
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Irrigated acreage rapidly expanded several fold
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Groundwater levels began to drop rapidly
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 over 36
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.
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)
 Water
Cycle Handout
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
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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.
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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
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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
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Almost all used for agriculture
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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.
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Provides water to seven states including California, with each
state's water use determined by the Colorado River Compact
of 1922.
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California permitted to use 4.4 million acre-feet annually.
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For over a decade, California has been using well beyond the
1922 allotment.
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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:
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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
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water (salts)
Pre-ag existance
Ag production induced
Water Pollution Mitigation
 A couple
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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)