Agricultural Irrigation

• Author: John H. Davidson
• Pages: 51-63

Page 51

Chapter 4

Agricultural Irrigation

John H. Dav idson

Irrigation is a key element in any analysis of domestic and global agriculture. It has been a central part of

agriculture for millennia, and is known to have been practiced by indigenous peoples in the American

Southwest as early as 100 B.C.1 Ruins of early irrigation ca nals are still visible in the vicinity of the

Gila and Sa lt Rivers in what is now A rizona; the canals served to irrig ate lands in the Pima and Papagos

pueblos.2 Similarly, in what is now New Mexico, the Indians in the Rio Grande Valley irrigated their farms

long before the Spaniards arrived at the end of the 15th century.3

Despite these and numerous other eorts throughout the Southwest, large-scale irrigation was not suc-

cessful until the Mormons entered the Salt Lake Valley in Utah in 1847.4 By 1850, 926 Utah farms involv-

ing a total of 16,133 acres were under irrigation.5 By 1860 there were 77,219 irrigated acres of farmland

growing crops that were vital to the survival of the community.6 e Mormon achievement is the rst large

agricultural economy in the West dependent entirely upon articial irrigation.7 e centra l engineering

method was t he ecient and sustainable diversion and conveyance of canyon strea ms to distant va lley

farmlands.8 e Mormon success provided the model from which the rst generations of irrigation in the

United States grew.9

Irrigation is today a feature of agriculture in all 50 American states.10 Over 55 million acres are irrigated,

and nearly 50 million of those acres are on farms of 200 acres or more. Just under 30 million of those acres

are on farms with more than 1,000 acres.11 In 1997, the West held 78% of the country’s irrigated land,

but recent trends forecast faster growth in the East.12 From 1987 to 1997, irrigated land increased by 14%

in the West, a nd 38% in the East.13 Substantia l increases in irrigation must be a nticipated as land prices

escalate, the total amount of land available for agriculture diminishes, demand for all crops increases, costs

of irrigation infrastructure are lowered, and nancial capital concentrates.14

When done well, irrigation has only minor environmental impacts.15 It can conserve water, allow full

utilization of prime soils, increase productivity of ex isting tilled acres, enhance the production of essential

human foods, and provide resiliency during periods of drought.16 Irrigation has the potential to help agri-

culture shift toward sustainability—using resources to serve both present and future generations. at this

1. D  O  F I S  (G.J. Homan et al. eds., 2d ed., 2007) [hereinafter D].

2. N R C, C.   F  I, A N E  I 9 (Nat’l Academy Press, 1996) and J.L.

S  ., L C  W R 326-27 (4th ed. 2006).

3. See generally S. C, M: C   A  N N M (1988).

4. S  ., supra note 2, at 327.

5. United States Seventh Census, 1850, 1006 (1853).

6. United States Eighth Census, 1860, Agriculture, 180 (1864).

7. Id.

8. Id.

9. Id.

10. C A. J, G E 203 (2010).

11. U.S. Dep’t. of Agric., National Agricultural Statistics Service, 2008 Farm and Ranch Irrigation Survey, in T C  A (2008).

12. J, G E, supra note 10, at 203.

13. Id.

14. L J. MD, F R  S: W, A,   E   A W

1-9 (1999).

15. Id.

16. Id.