WORKING PAPER NO. 35
COLUMBIA RIVER BASIN PROJECT
For Water Supply and Water Quality Management
WILLAMETTE RIVER BASIN (OREGON)
IRRIGATION TRENDS
DATE: November 20, 1962
Prepared by RLC
Reviewed by _
Approved by
DISTRIBUTION
Project Staff
Coopers ting Agencies_
General
U. S. DEPARTMENT OF HEALTH,EDUCATION AND WELFARE
Public Health Service
Region IX
Division of Water Supply and Pollution Control
Room 570 Pittock Block
Portland 5, Oregon
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This working paper contains preliminary data and information
primarily intended for internal use by the Columbia River
V
Basin Project staff and cooperating agencies. The material
presented in this paper has not been fully evaluated and
should not be considered as final.
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WILLAMETTE RIVER BASIN (OREGON)
IRRIGATION TRENDS
Table of Contents
A. General 1
B. Upper Willamette 1
1. Present Situation 1
2. Potential Use 2
C. Middle Willamette 3
1. Present Situation 3
2. Potential Uses 6
D. Lower Willamette 6
lo Present Situation 6
9
Prepared by; Eeoaomie Studies Group
Watex1 Supply and Pollution Coatrol
.Fs'OgraiSj, Pacific Northwest
November 1962
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IRRIGATION TRENDS C=>1
IN THE WILLAMETTE BASIN
A. General
Water quality is of considerable importance to irrigated agriculture.
In addition, irrigation return flows can influence the quality of re-
ceiving waters. Because of their similarity So other water supply
problems, irrigation withdrawals and quality requirements have been .
examined elsewhere in this report. However, in order to provide a basis
for anticipating future irrigation needs, and in order to relate irri-
gation to land requirements, irrigation trends (both historical and
potential) are briefly examined in the following parts of this section.
B. Upper Willamette
1. Present Situation
Agricultural use of water in the upper Willamette basia is fast
growing, A higher proportion of farms make use of irrigation in the
upper basin than ia either the middle or lower portions of the basin,
and the percentage of total farm land irrigated is somewhat higher than
in the other areas. In 1959 about 37.3 percent of the farm land in the
region was in irrigated farms,, while 602 percent of the farm land was
actually irrigated. The comparable figures in 1954 showed 31.3 percent
of farm land ia irrigated farms and 404 percent actually usssdss irrigation*
during the year0 Because the cost of irrigation is high, its *ss© is
restricted to crops which provide a high return per acre uades sui£i°
vation. (For examples, in 1959S 94 percent of the vegetable esops ssd
93 percent of the mint crop were produced under irrigation.)
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C-2
Irrigation is conducted largely with sprinklers and on an individual
basis. Three small irrigation districts accounted for only about 1,640 acres
of the 22,469 acres irrigated in the area in 1959, and supplemented fara
.sources on another 940 acres. Farm ground waters irrigated 8,358 acres;
fares surface waters irrigated 8S700 seres; amd 3a091 acres Bsss1® itrsigaeed
by a combination of farm ground and surface mates'©«
TABLE I ^
Irrigation in Upper Willamette Basin (Lane County)
1954 1959
Total farm land (acres) ..... 442,158 365,310
Percent of farms irrigated (acres) 24.4% 31.7%
Land irrigated (acres). ............. 19,457. 22,469
Land irrigated by sprinkler systems ..........DC... 85.6%
Land irrigated by farm ground water' ............ooo 3702%
Land irrigated by farm surface watero 0 ....... » o 0 0 0 0 38.6%
Land irrigated by combination of ground and surf&e© ^a£a5?s0 . . 0 13o7%
Land irrigated by irrigation organisatiesa mates' . . . 0
c o o o
ffeq seas©® e® ©sspxsee fsogsess ia &?slgG£i@ms
1954 t© 1959 £h© tapper fessia wi£m©®©@d a IS p©reeisfe sis© ia
isrigstion9 esapsssdl 60 a 23 p@re©n£ ris© ia the l®a©r feasisa sad aa 11
pereene rise in £a@ saiddlle bssia°°y©S eha iaambtgg ©f &ss®& of fas®
J-/ Uo So Cea@ts@
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dropped 17 percent in the upper basin, only 3.5 percent in the middle basin,
and rose one percent in the lower basin, indicating that contraction in
available farm land probably results in greater proportionate use of irri-
gation on land remaining under cultivation. Another reason for anticipating
greater use of irrigation in the future is a demonstraced £ead©ffi&y is s"eg©ae
years to irrigate pasture.
The U. S. Department of Agriculture has, on the basis of population
projections similar to the ones employed by this office, indicated that by
2010 irrigation will characterize 80 percent of cropland under cultivation
in the upper Willamette basin. Water needs for irrigation are expected to
amount to about five percent of the annual water budget, as compared to
less than one percent in 1960.
TABLE II -^
Anticipated Increase in Upper Willamette Basin Irrigation, Ii59 -
1959
Aeres under Irrigation . „ . . . . 0 o . 0'22,469 45P©00 100,000*
Required water velum® (ser©=fee£> . . . . 66,420 110,000 224,730
Co Middle Willamette
1. Present Situation
The middle Willamette basia is ©a® of tfe® B3©»£fos?S!8£'s
cultural areas, bat the ®@fi©ga£®D msisfs
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In spite of some contraction in farm land, and a very noticeable drop in
number of farm units°°conditions normally associated with broad use of irri°
gation and other intensive farm practices—the level of irrigation ia
was little changed from 1954, «hen 31,2 percent of the farm laad of th@
?*a© contained ia isrigat©d fas^Sj aad §07 perceae of total fsjm aciroags
irrigated.
Irrigation is conducted largely on an individual basis with watts' d@°
5?ived from farm sources0 In 1959 irrigation organizations provided water
for only 7,105 of the 101,037 acres irrigated. Farm ground water sources
were used on 36,813 acres; farm surface water sources supplied 32,363
acres; and farm ground and surface sources in combination ner© ased £©
irrigate another 19,326 acres. Ia a small number of e©§©©D fasm
supplies were supplemented by irrigation organisation waisaijo
Sprinkler systems provid© th® priaeipal as@th@d ®f fe5?lg£££«ja isa
saiddio feasia0 aaS w®1® ussd ©m % pgifisigafi ©£ th© laad isreigaeedL ia 19
Tfo© aorehera eouaeie®. Polk atad YsssMiip g@ly £© a gs ©ssteat ©a
face Ba£©g© for irrigation tfeaa d@ B©iatoac Lism and Marios ©©waeies;, sad
they also lead ia the pr©p©r£i@ss of i5?E'ig©£i©a cosaducttad b
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C-5
Irrigation: Prevalence and Trend, by Counties, 1954-1959
Farm land Percent
County
TOTAL 1,540,153
1954
Farms Irrigated
1959 1954
Land Irrigated
(acres)
1959 • 1954
Beaton
Linn
Marion
Polk
Yamhill
205,340
490,060
351,397
232,683
260,673
214,342
509,899
367,754
237,321
272,572
27.5
26.9
35.9
18.3
17.0
24,5
21c5
27,9
14.5
15.9
9.HS
23,478
44 . 861
9,485
13,497
.9,139
19.G99
42 , 131
8, SOS
12,475
1,601,888
27.0
22.0 101,037 91,652
Isi?i
(As a
Linn
45%
39%
38%
15%
40%
27%
49%
aad Method, by G©um£ie©
Fasm Growad Fasm i^sfac© C©mfeifaa£i®a ©f
17%
95%
11%
- S. Census
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2. Potential Uses
As indicated in the economic base study, agriculture is expected to
continue to be a leading economic activity in the middle Willamette ba@ia»
Although the population of the middle basin is projected to significantly
higher levels, the increase is expeeted to be concentrated ia presently
urbanized areas and probably may not be expected to de££ae£ fe@ sa
appreciable extent from available farm land, Indeed, transition from
forest to cropland and pasture may result in a net addition to farm land
4/
by 1985. ~" Larger markets, possible shifting of crop distribution from
field seeds and hay in favor of greater production of vegetables and irri-
gated pastureland, and the larger capitalization per acre characteristic ©£
concentration of farm holdings—a pattern apparent in the ares— should
combine to contribute to an appreciable increase in irrigated faming.
While the region may be expected to lag behind the upper md l
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C-7
f (
However, the larger Immediate market and the relative scarcity of agri->
cultural land contribute to use of intensive agricultural practices,
including irrigation. Although a considerably smaller proportion of the
farms in the lower basin are irrigated than in either the middle or the
upper basin, both the proportion of total farmland in irrigated farms
the proportion of farmland irrigated compare closely
and in recent years, the prevalence of irrigation has spread faster in the
lower basin than in other areas. In 1959 about 34.6 percent of the farm-
land of the lower Willamette basin was contained in irrigated farms, and
about 5.9 percent of total farm acres were irrigated. These figures indi-
cate that a marked increase occurred over 1954, when 20.6 percent of the
region's farmland was in irrigated farms and 4.8 percent ms irrigated„
As in other parts of the Willamette basin, farm sources ©f %*at©r @ss£»
weigh irrigation organization source©; s«d spsieklers as® £te psiae&pal
5£@6la©d @S 4sT?iga£ioffi0 I
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TABLE V -
Irrigation: Prevalence and Trend by Counties, 1954-1959
County Farmland (acres) % of Fams Irrigated Land Irrigated (acres)
19S9 j.954 1959 1954 1959 JL9J4.
Clackamas 319,048 310,550 13.9 8.8 11„054 i0©$®
Multnomah 89,379 71,058 2607 11.0 10,212 4,713
Washington 211,108 236,203 20.9 14.1 15,169 U
TOTAL 619,535 617,811 18.0 10.9 36,445 29,509
Irrigation: Sources and Method (as percentage of total seges
1959), fey
YJo <«/ea'ir' T*Jjsi C'/Sh'iT* TSPsjiPm
wcs. iggga w)&t.*i*S jg g&jsm
Clackamas
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2. Potential Uses
Growing population in the study area indicates continuing diversion
of farmland to dwelling and industrial uses. By 1960 perhaps two-thirds of
the best cropland of Multnomah County had been converted to urban use; and
the process continues, with greatest speed in Washington County, but in the
other two counties of the area as well.
That interaction of growing consumer demand with decreasing supplies
of cropland should result in more intense farming practices and greater use
of irrigation seems obvious. No studies are available to indicate the
probable extent of future irrigation, but a preliminary projection may be
made for design purposes. The Oregon Committee for Development of National
Inventory of Soil and Water Conservation Needs has projected fche level of
cropland anticipated in 1975, and it would appear likely that the prevalence
of irrigation will display the same three percent annual rate of increase
over that period that it has exhibited in the post-war years. On the basis
of these figures, the results indicated in Table VII are obtained.
TABLE VII
Total Cropland and Irrigated Cropland, in the Lower Willcacstt® Bas£a£
'6/
County Total Cropland (acres) —' Irrigated Cropland (acres)
1959 1975 1959 &
Clackamas 147,605 125,000 11,064 22,008
Multaomah 37,210 30,000 108212
Washingtoa 137,708 1328SOO 15,169
TOTAL 3228523 28?,
j>/ Oregon Committee for Development of a National Inventory of Soil and
Water Conservation Needs, March 1960.
2/ U. S. Census of Agriculture. 1959.
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The indicated doubling of irrigated cropland does not seem out of
place when demands on the available land and the historical trend of irri-
gated agriculture is considered. For the purposes of this analysis it is
estimated that by 2010 almost all of the cropland of Multnomah County, and
a major part of the cropland of the s?e@t ©f the lover basic, will be
irrigated.
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