For Water Supply and Water Quality Management

                    IRRIGATION TRENDS
DATE:  November 20, 1962

Prepared by    RLC

Reviewed by _

Approved by	
Project Staff
Coopers ting Agencies_

                    Public Health Service
                          Region IX

        Division of Water Supply and Pollution Control
                    Room 570 Pittock Block
                      Portland 5, Oregon

This working paper contains preliminary data and information

primarily intended for internal use by the Columbia River
Basin Project staff and cooperating agencies.  The material

presented in this paper has not been fully evaluated and

should not be considered as final.


                     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

Prepared by;  Eeoaomie Studies Group
              Watex1 Supply and Pollution Coatrol
                      .Fs'OgraiSj, Pacific Northwest
              November 1962

                            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.)


     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'    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@

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 -

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 
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


    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

      Irrigation:  Prevalence and Trend, by Counties, 1954-1959

                 Farm land             Percent
TOTAL   1,540,153
         Farms Irrigated

          1959     1954
              Land Irrigated

               1959 •    1954
44 . 861
42 , 131
8, SOS
     22.0   101,037   91,652
             (As a
                                    aad Method, by G©um£ie©
        Fasm Growad  Fasm i^sfac©  C©mfeifaa£i®a ©f
      - S. Census

    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

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
 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
                                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

    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£

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.


        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