A New Era for Irrigation (1996) / Chapter Skim
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3 IRRIGATION TODAY
3 IRRIGATION TODAY
Pages 46-82
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From page 46... ...
This transition was driven by economic change: in the late nineteenth century, western promoters turned to irrigation when mining, open range cattle, and dry farming economies proved unable to sustain western settlement (Webb, 1931~. During this period, foundations were laid to support irrigation water rights laws, advances in engineering, mutual water district organization and financing and these supported early irrigation in areas such as California, Colorado, and Utah.
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From page 47... ...
Readers already well-versed in the status and trends of irrigation today are encouraged to proceed to Chapter 4, where the committee explores the deeper cause and effect relationships that underlie the statistics. IRRIGATED AGRICULTURE Irrigated Land in Farms Irrigated agriculture occurs on just 14.8 percent of the harvested cropland and yet produces 37.8 percent of the value of crops (Figure 3.1~.
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From page 48... ...
The drought years of the 1950s and the development of centrifugal pumps and more economical power sources stimulated irrigation development in the southern Great Plains, where ground water is pumped from the Ogallala aquifer. With the advent of the center pivot sprinkler irrigation systems, and with ground hater readily available, irrigation expanded rapidly in the central Great Plains luring the 1960s and 1970s.
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From page 49... ...
, the combination of improved yields on irrigated farms and the increase in the relative acreage devoted to irrigation accounted for 28 percent of the national increase in corn production, 20 percent for sorghum, and 12 percent for wheat from 1950 to 1977 (Frederick and Hanson, 1982~. WATER USE FOR IRRIGATION Irrigation water typically is measured in terms of withdrawals or consumptive use.
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From page 50... ...
These estimates reflect the importance of the four influential factors: irrigation technology, crop prices, annual commodity program acreage restrictions, and weather. Relaxed acreage restrictions, improved irrigation technology, and high crop prices in the 1970s accelerated irrigation development, increasing total irrigated area from 38 million acres in 1972 to 52 million acres in 1981.
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From page 51... ...
51 TABLE 3.1 Irrigated Area in the United States Region1987 (thousand acres) 1992 (thousand acres)
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From page 52... ...
Most states rely on a combination of surface and ground water supplies for irrigation purposes (see Table 3.3~. Surface water accounted for 63 percent of total irrigation withdrawals in 1990.
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From page 55... ...
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From page 56... ...
Freshwater withdrawals for agriculture are used mainly for crop production, with 98.4 percent of surface water and 93.8 percent of ground water used in irrigating cropland (Solley et al., 1988)
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From page 57... ...
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From page 58... ...
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From page 59... ...
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From page 60... ...
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From page 61... ...
Although surface water use increased slightly in 1985, declines in ground water use were greater than the increases in surface water use (Bajwa et al., 1992~.
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From page 62... ...
. Modern irrigation technologies such as sprinkler, center pivot sprinkler, and microirrigation rely on energy and closed systems to deliver water to plants.
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From page 63... ...
63 cat C)
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From page 64... ...
Water prices usually reflect only the cost of supplying water and generally do not convey market signals. Irrigation water costs vary widely, reflecting different combinations of water sources, suppliers, distribution systems, and other factors (Gollehon et al., 1994~.
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From page 65... ...
21. TABLE 3.8 Labor Requirements and Capital Costs for the Various Irrigation Methodsa Labor requirement Capital Costsb System (in/acre-irrigation)
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From page 66... ...
Economic factors, especially crop and energy price levels, will be important to the future growth of irrigated agriculture. Because their yields and production costs are generally higher, irrigators' profits are more sensitive than those of other farmers to agricultural prices.
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From page 67... ...
Rising real crop price levels can offset higher water costs and encourage additional ground water pumping. But the lure of additional profits from irrigation would not alter the trend for more of the region's water to flow to municipalities and industries where water values are much higher than in irrigation.
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From page 68... ...
Environmental issues related to water consumption and water quality in landscape irrigation have become more prominent with the expansion of golf courses and the turfgrass sector generally. The relative significance of environmental issues associated with irrigation varies between regions of the country, but the types of environmental issues confronting irrigation generally are the same coast to coast.
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From page 69... ...
The committee cannot predict how the legislative pendulum will shift given the current, more conservative bent of Congress and emphasis on cost cutting, but its feeling is that while there will be some changes, the American people will not support a wholesale retreat from environmental protection. Key environmental issues with direct association to irrigated agriculture are instream flows and wetlands, salinity and drainage, water quality, and anthropogenically induced climate change.
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From page 70... ...
Over 30 million acres of cropland have been enrolled. Sodbuster provisions require that farmers who convert highly credible land to agricultural commodity production do so under an approved conservation system, or forfeit eligibility for USDA program benefits.
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From page 71... ...
U.S. Geological Survey National Water Quality Assessment Program Since 1986 the NAWQA program has conducted assessments of national and regional status of ground water resources and monitors trends in factors that can affect ground water quality.
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From page 72... ...
In Idaho, ground water pumping by irrigators along the Big Lost River over the last 15 years has caused the dewatering of the lower reach of the river and lowered ground water levels precipitously (High Country News, 1995~. Largescale irrigation projects constructed by the Bureau of Reclamation have drastically altered habitat conditions in major river basins across the West, including the Platte River, the Colorado River, the Columbia River, and the Snake River.3 Many fish and other aquatic species that depend on habitat values in these rivers are listed as threatened or endangered under federal and/or state endangered species laws, although it must be noted that irrigation withdrawals are only one factor among many (e.g., hydroelectric power generation)
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From page 73... ...
According to recent estimates, irrigated cropland in the West accounts for 89 percent of quality-impaired river mileage. Irrigated agriculture accounts for more than 40 percent of the pollution in lakes with impaired water quality (U.S.
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From page 74... ...
In 1992, the Central Valley Project Improvement Act (P.L.102-575, Title XXXIV, 106 Stat.4706) set aside 800,000 acre-feet of water previously delivered by the federal Central Valley Project to agricultural users for fish and wildlife habitat.5 In addition, water users were required to pay surcharges on irrigation water to be used to finance environmental restoration.
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From page 75... ...
The CO2 fertilization effect will affect plant growth and possibly water supplies. Research results suggest that the increasing levels of atmospheric carbon dioxide (CO2)
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From page 76... ...
Water harvesting and storage in small ponds and reservoirs are increasingly becoming a major element in golf course design. Treated effluent water, although not technically "surface water," is an alternative source of supplemental irrigation water.
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From page 77... ...
The securing of water supplies and other natural resources has implications for irrigated agriculture in the United States, particularly in the Northwest, Southwest and Missouri River basin. Today, American Indians own 2.7 million acres of cropland, of which 64 percent is irrigated.
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From page 78... ...
During the course of development of irrigation in Indian Country, there has been considerable controversy over the construction, payment, and repayment of construction costs associated with Indian irrigation projects. The controversy has greatly affected the condition of Indian irrigation projects today.
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From page 79... ...
As a result, policy decisions related to Indian irrigation projects and water resources may significantly affect water resources available to irrigated agriculture.
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From page 80... ...
1975. Report to the United States Senate Committee on Interior and Insular Affairs on the Status of Construction of Indian Irrigation Projects.
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From page 81... ...
National Water Summary 1985 Hydrologic Events and Surface Water Resources.
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From page 82... ...
Golf Association, National Golf Foundation, and the Golf Course Superintendents Association. Toro Company.
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