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• Board Meeting Date: 3/18/2008
• Description: IWMD Section - Presentation of Agricultural Water Conservation Paper
• Board Meetings - Doc Type: Memo

Section 5
Legal and Engineering Considerations
urban water uses provide base flows for many of the small urban creeks that support
riparian habitat and aquatic species. Irrigation ditches also support important riparian
vegetation such as cottonwoods and willows. These plants in turn support fauna that
would not be able to exist without them. Lining the canals, ditches, and laterals
throughout the state with concrete would result in a significant loss of important
riparian habitat. Reduced return flows could tend to have an adverse affect on water
quality as the dilution flows are reduced; however, depending on soil conditions
some water quality improvements could occw- if less salts and minerals are leached
from soils in the return flow.
In a change case, the
._~''~-'`k,
~'""" measure of the water right
~
Y~
~' ~
it,.,. , ~,~ ~.,~
~. is the amount that was
t
:ham - ., ~ ~ v . `~--•. `a~.,
`" historically consumed (not
_
• ~ ~ the amount diverted) under
~ the water right. Thus, only
.~~;.'~i _ S~ _. ~~',~_ .r~*„~-};.•:~1,~;,„„~ ~,. ~ the amount of water that
• '"~' ~ the crops consumed (minus
• ""~; ~~" effective precipitation) may
~ ~ '~
[.~~~ be transferred for a new
~~' ~ ~ ~`~' ' consumptive use at the
^:. ~
~ ,~ ~ ~
~
existing or a new location.
,
tr~
~~ '
~~ {
'
~ This limitation ensures that
th
h
ill
t
l
,,
±
:
~ e c
ange w
no
en
arge
~
;{
<, -. ~,.~
the historical impact of the
x ;: water right on the stream
~
rL:,. ~y„ ~, a~
'~ . -~.~ ~ ~`¢
system, avoiding injury to
• i`
ate,: ~~,~, ~ '' other water users. In
~ ' ~' ~
;~,1 f ~ ~~ "' ;,ry ~~~ i `{ addition, in a change of
;
~~~. .
~
~~"~','~~
` , ~,
;~
4 water right proceeding, the
,
~y
,
,` ~ ~ ,_ ~ ,
~
~~~,
'~~'
f ~ ~ ~~ ? applicant must take
appropriate steps to ensure that historical return flows from the use of the water in
amount, timing, and location are maintained. This is requ ired because other water
users rely, and are legally entitled to rely, on those return flows to support their
appropriation and uses of water.
DRAFT 5-3