Response to Report by Barry L. Dutton for Boone Cole, Jerry Laskody, Shane
Orien, Wayne Blevins and Tim Orr. Historic Water Use and Crop Water
Requirements at the Flathead Indian Irrigation Project. March 5, 2015
Prepared by:
Seth Makepeace, CSKT Hydrologist
Wade Irion, P.E., DOWL
March 18, 2015
Highlights of Technical Memorandum in response to Dutton Report
The following information contains highlights from our review of the Dutton report, the details of
which are found in the attached technical memorandum. In order to prepare comments, we also drew
from a February, 1994 Land & Water Consulting Report titled “Flathead Irrigation Information System
Summary Report and Irrigation Guide,” which is attached as an appendix to the Dutton report.
1) The 1994 Land & Water report contains valuable information on historic water use and energy use
on the Flathead Indian Irrigation Project. However, the Dutton report does not accurately characterize
the historic water use information contained within the 1994 report. The Dutton report references
historic irrigation application amounts up to 28 inches per season. Appendix B to the Land & Water
Report contains field-by-field reporting of measured rainfall and irrigation applications for each field
and crop-type in the 1989-1992 study period. In no instance was a 28 inch per season irrigation
application amount reported, and we can only conclude that Dutton reports in error, or is incorrectly
including rainfall and irrigation in the 28 inch figure as is suggested by Appendix B6 to the Land &
Water report. We summarize the data from the field-by-field measurement program below for the
1989 – 1992 period.
Summary of applied irrigation water, in inches per season, for the 1989-1992 period from Appendix B
(Land & Water, 1994)
1989
Alfalfa Alfalfa Barley Grass Grass
Oats Oats Potatoes Spring Winter
through
/
hay
pasture
/
Wheat wheat
1992
grass
Peas
Average
Maximum
Minimum
Count
10.4
17.7
2.8
48
6.3
8.0
4.0
3
3.2
6.0
0.0
17
15.5
22.9
9.8
11
14.2
18.1
10.2
2
4.7
8.3
1.8
5
6.9
9.3
4.5
2
10.8
23.5
5.8
9
8.7
16.1
0.0
12
7.2
13.8
0.0
24
If we combine all field-by-field irrigation measurements for all crop types for the 1989 – 1992 period
from Appendix B of the Land & Water report, we see that the average measured irrigation application
was 8.3 inches per season, the 80th percentile (lower) irrigation application was 4.8 inches per season,
and the 20th percentile (higher) irrigation application was 13.1 inches per season. The data found in
Appendix B tells a far different story than that reported in the Dutton report.
2) The Dutton report asserts that the proposed Compact will not meet historic farm deliveries and uses
the Farm Turnout Allowances from the 2013 version of the proposed Compact as a benchmark. Due, in
part, to substantial concern by affected irrigators the FTA concept was replaced by the River Diversion
Allowance concept in the 2015 version of the proposed Compact. RDAs are allocations of water
measured at the source of supply to an irrigated area, and the tabulation below clearly demonstrates
that RDAs can meet historic delivery amounts. Below RDAs are reported by dividing the RDAs by the
i
acres served, accounting for those RDA amounts that represent water conveyance from one RDA area
to the next:

45.4 inches of water (3.78 acre-feet) per irrigated acre to be diverted into the Jocko Valley when
including inflow from unadministered locations;

20.9 inches of water (1.74 acre-feet) per irrigated acre to be diverted into the Mission Valley when
including inflow from unadministered locations and increases in Flathead River pumping of
approximately 20,000 acre-feet in a dry year. This value also does not account for the extensive reuse of water within the interior of the Mission Valley, which is not precluded in any way by the
proposed Compact, and which increases the effective allowance. For direct comparison, this
diversion allowance matches the total irrigation diversion (administered, unadministered, and
Flathead pumping) to FIIP in the Mission Area under current conditions (1.74 acre-feet in Dry Years),
based on records of measured diversions.

23.6 inches of water (1.97 acre-feet) per irrigated acre to be diverted into the Little Bitterroot
Valley in all water year types to match the status quo.
Differences in the values between valleys reflect variable conveyance efficiencies, available water
supply, and re-use of water. These per-acre diversion allowances are based on the assumption that all
acreage mapped as active irrigation is irrigated in a given year, when in fact, between 80% and 85% of
the active irrigation is irrigated in a given year (FIIP Project Operator, personal communication). This
provides a large additional buffer for the per-acre irrigation water supply.
3) The Dutton report incorrectly defines how RDAs were calculated and demonstrates a lack of
understanding of the concept. RDAs do not define the allocation of water to individual farm units, but
allow the Project Operator and irrigator’s full flexibility to manage RDA allocations within RDA
geographic areas. This means that irrigators can shift water between tracts, prioritize specific fields
and crops, and apply re-use water or other incremental water derived within a geographic area.
4) The Dutton report does not correctly portray the value of the RDA allocation from the Flathead
River Pumping Plant. Water from this plant can directly serve the approximately 29% of the total FIIP
acres under Pablo Reservoir, and can provide direct irrigation water supply benefits to the remainder
of the Mission Valley, since approximately 25,000 acre-feet per year of canal water are moved from
south to north in the Mission Valley.
5) The Dutton report does the irrigation community a disservice by reporting irrigation water
requirements based on potential evapotranspiration. While some irrigators are able to apply water
near potential on certain fields, the FIIP is a deficit water-supply irrigation project. This is well
documented in the Land & Water Report, and has been reported as early as the 1939 Hodges Report –
decades before the implementation of the interim instream flows.
ii
Response to Report by Barry L. Dutton for Boone Cole, Jerry Laskody, Shane
Orien, Wayne Blevins and Tim Orr. Historic Water Use and Crop Water
Requirements at the Flathead Indian Irrigation Project. March 5, 2015
Prepared by:
Seth Makepeace, CSKT Hydrologist
Wade Irion, P.E., DOWL
March 18, 2015
We have prepared the following comments in response to the above-noted synopsis report. In
order to prepare comments, we also drew from a February, 1994 Land & Water Consulting
Report titled “Flathead Irrigation Information System Summary Report and Irrigation Guide,”
which is attached as an appendix to the synopsis report. The earlier Land & Water Report was
compiled in part to support an irrigation scheduling program and to complete energy audits
and improve energy use at farm pumps. The irrigation scheduling portion was prepared based
on four years of field-scale rainfall, irrigation, and soil moisture measurement. The Land &
Water study collected field data during the period 1989 – 1992 and provided
recommendations for improving the efficiency of on-farm water use and energy use on the
Flathead Indian Irrigation Project (FIIP).
Our responses were developed and structured by: a) reviewing each point in the Executive
Summary of the Dutton report or citing to the appropriate discussion area later in the memo;
b) reviewing themes found throughout the synopsis report; and c) examining the conclusions
of the Dutton report.
Executive Summary of Dutton Report
1. The Dutton report indicates that irrigators received up to 28 inches of water per season
during the 1989 – 1992 period, and that this is significantly greater than the amount
reported as the Farm Turnout Delivery in the proposed 2013 Compact. We direct the reader
to the section below on Historic Water Use which, using data directly from the Land &
Water (1994) report, reaches a much different conclusion than Dutton on historic water
use. Further, see the River Diversion Allowance section which demonstrates that Farm
Turnout Allowances from the proposed 2013 Compact are not a current or appropriate
measure of proposed irrigation allocations.
2. The Dutton report indicates that there is no commitment to ensure irrigators will receive
water they historically received. During the re-negotiation of the proposed Compact before
the current Legislature, irrigators repeatedly expressed concern with the defined Farm
Turnout Allowances, and therefore the current version of the proposed Compact defines
the water allocation in terms of River Diversion Allowances (RDAs). This allows irrigators
and the Project Operator the requested flexibility to deliver water within the boundaries of
1
3.
4.
5.
6.
7.
the Project as appropriate to meet the needs of the irrigators and in accordance with FIIP
operational guidelines. Since the irrigation water use right is dedicated to the FIIP, this
ensures the water will be allocated to irrigators within the project.
The Dutton report indicates the blocks of water provided under the RDAs are inadequate
and the Flathead Pumping Plant RDA can only service a limited number of acres. These
assertions are incorrect and are addressed under the Historic Water Use and River Diversion
Allowance sections below.
The Dutton report incorrectly indicates that water used in the past (e.g. re-use water or
incremental inflows within the interior of the project) is no longer available to irrigators. As
discussed under the RDA section below, this is incorrect and there is no restriction on
continued use of water derived within the interior of an individual RDA geographic area.
The Dutton report indicates there are no mechanisms to offset shortages, such as are found
in other parts of Montana. The FIIP is a Bureau of Indian Affairs irrigation project, and with
or without a compact, BIA rules may limit water marketing. However, the proposed
Compact has a specific section to address periods of water shortage, and there is no
limitation on how RDA volumes may be administered within individual geographic areas to
offset water shortage stresses.
The Dutton report indicates that the most common recommendation from the 1989 – 1992
work was to apply more water. This is intuitive, but is in direct conflict with the findings
reported in the Land & Water report, which demonstrates that the FIIP is a deficit irrigation
project and does not have access to more water.
The final paragraph of the Executive Summary suggests a set of serious, but
unsubstantiated opinions, regarding the future of agriculture under FIIP with the proposed
Compact. We would recast the report’s dire warning and present it as follows. The
proposed Compact preserves historic crop consumption use and provides flexibility for how
water is distributed; the proposed Compact brings major State and federal monetary
contributions to the FIIP, a project with an over 80 million dollar backlog of deferred
maintenance; the proposed Compact identifies new sources of water through the Flathead
River that can provide real benefit to large portions of the FIIP; and the proposed Compact
shields irrigators from the Tribes’ instream flows by implementing deferral periods and by
setting minimum instream flows that are notably below target levels or biologically-based
levels.
River Diversion Allowances
River Diversion Allowances identify the allocations of water to serve the FIIP. RDAs are defined
by geographic area and are defined for canal conveyance between reservoirs or trans-basin
diversions, for irrigation delivery areas, and for a mix of the two. RDAs are described for
administered locations as well as for unadminstered locations. Administered locations are
2
stream-canal intersections where water measurement and allocation tracking will be
completed. Unadministered locations are smaller inflows into the FIIP canal network where
measurement and tracking is not proposed. Unadminstered inflows are defined as part of the
RDA irrigation water allocation and will continue to be available for use
The Dutton report incorrectly defines how RDAs were calculated in the HYDROSS model. In fact,
RDAs were determined by matching historical records of actual canal diversion (47
measurement sites), as well as stream flows (36 measurement sites) and reservoir levels (14
reservoirs) and then applying a range of reasonable improvements to irrigation operations that
are termed Operational Improvements in the proposed Compact. Operational Improvements
generally look to save between 10% and 15% of the historical canal diversion amounts. We note
that some of these Operational Improvements are similar to the proposed mitigation actions
identified in Section 5.0 of the Dutton report.
River Diversion Allowances do not define the allocation of water to individual farm units, but
leave that to the discretion of the Project Operator and irrigators. However, in the interest of
providing an understanding of the RDA levels on a per-acre basis, this information is provided
as follows for dry water year conditions (highest stress period) under the proposed Compact.
The values below are prepared by dividing the RDAs by the acres served, accounting for those
RDA amounts that represent water conveyance from one RDA area to the next:

45.4 inches of water (3.78 acre-feet) per irrigated acre to be diverted into the Jocko Valley
when including inflow from unadministered locations;

20.9 inches of water (1.74 acre-feet) per irrigated acre to be diverted into the Mission Valley
when including inflow from unadministered locations and increases in Flathead River
pumping of approximately 20,000 acre-feet in a dry year. This value does not account for the
extensive re-use of water within the interior of the Mission Valley, which is not precluded in
any way by the proposed Compact, and which increases the effective allowance. For direct
comparison, this diversion allowance matches the total irrigation diversion (administered,
unadministered, and Flathead pumping) to FIIP in the Mission Area under current conditions
(1.74 acre-feet in Dry Years), based on records of measured diversions.

23.6 inches of water (1.97 acre-feet) per irrigated acre to be diverted into the Little
Bitterroot Valley in all water year types to match the status quo.
Differences in the values between valleys reflect variable conveyance efficiencies, available
water supply, and re-use of water. These per-acre diversion allowances are based on the
assumption that all acreage mapped as active irrigation is irrigated in a given year, when in fact,
between 80% and 85% of the active irrigation is irrigated in a given year (FIIP Project Operator,
3
personal communication). This provides a large additional buffer for the per-acre irrigation
water supply.
Defining the FIIP irrigation allocation in terms of RDAs represents a significant adaptation in the
2015 proposed Compact relative to the 2013 proposed Compact. This change seeks to address
concerns raised by irrigators that prescribing Farm Turnout Allowance values would have
eliminated the flexibility to adjust allocations between individual irrigators or to move water
between tracts of land. We note the following regarding the RDAs, all of which are contrary to
assertions in the Dutton report:




RDAs do not define the allocation of water to individual farm units, but leave this to the
discretion of the Project Operator and individual irrigators. This flexibility allows irrigators to
move water between tracts within an RDA area, it allows the Project Operator to preserve
the duty system of water allocation if this is established to be FIIP policy, and it allows the
Project Operator and the irrigator’s complete operational flexibility to divert and deliver
RDA allocations within the interior of the project.
RDAs do not restrict water re-use, capture of rainfall, or other water derived within the
interior of an RDA geographic area as occurs presently. The RDAs define water allocation at
the primary source of supply to an irrigation service area (RDA area) and are intentionally
silent on operations within individual irrigation service areas.
Since RDAs do not restrict the amount of water to be delivered to individual tracts, an
individual irrigator growing, for example melons or potatoes, has the same opportunity to
increase their irrigation amounts as they do under the current FIIP operations. This is in
direct contrast to the statements in the Dutton report (e.g., see bottom page 6).
The RDA allocation for the Flathead Pumping Plant is significantly increased above historic
pumping levels and the proposed Compact additionally provides a monetary contribution to
offset pumping costs. Contrary to conclusory points in the Dutton report, water from the
Flathead Pumping Plant can directly serve approximately 29% of the FIIP acres, and
indirectly augment irrigation supplies throughout the Mission Valley. This occurs because
approximately 25,000 acre-feet of water per year are moved from the south Mission Valley
to Pablo Reservoir. Reducing this south to north export of irrigation water provides direct
benefit to the irrigation water supply throughout the Mission Valley.
Historic Water Use
In the Executive Summary, Section 3.0, and the Conclusion section of the Dutton synopsis
report, the author suggests that the proposed Compact will provide significantly less water to
irrigators than was historically available. To substantiate this statement, the author indicates
that irrigators applied up to 28 inches of water to crops (Page 1 of Dutton report) and then the
author benchmarks this to the Farm Turnout Allowance numbers (Appendix A4 to Dutton
4
report). We, in no way, concur with this conclusion and note the following points, which are
followed by a review of the measured, field-scale irrigation application values reported in Land
& Water (1994):


Farm Turnout Allowances were part of the former Water Use Agreement leading to the
2013 version of the proposed Compact, but are not a part of the 2015 proposed Compact.
Farm Turnout Allowances are, in no way, the appropriate measure to describe delivery to
farms. Farm Turnout Allowances have been replaced by River Diversion Allowances; RDAs
are discussed above, but in brief, they allow much greater flexibility for the Project
Operator and irrigators to tailor individual water allocations to meet their crop priorities
and irrigation water requirements.
The Dutton report cites that individual irrigators applied up to 28 inches of water. We
reviewed Appendix B to the 1994 Land & Water Report, which summarized measured
rainfall and irrigation for each field in the 1989 – 1992 study period. In no instance were we
able to document a field that received 28 inches of irrigation water, and can only conclude
that the reference to 28 inches of applied water is either erroneous or includes both
irrigation and rainfall amounts.
Since the 1994 Land & Water Report forms the basis for the estimation of Historic Irrigation
Amounts in the current Dutton synopsis report, we summarize Appendix B of that original
report, which provides a field-by-field (and therefore crop-by-crop) tabulation of measured
rainfall and irrigation volumes for each of the 1989-1992 years.




Appendix B information is summarized in Tables 1.0 and 2.0 by crop and by year for
measured irrigation amounts only, since irrigation water, and not natural precipitation, is
the subject of the proposed Compact.
Table 1.0 is a summary of applied irrigation water (from Land & Water) for the accumulated
1989-1992 period.
Table 2.0 is a summary of applied irrigation water (from Land & Water) for each of the
1989-1992 years.
Each table reports, by crop:
 Average field-measured applied irrigation water, in inches per season;
 Maximum field-measured applied irrigation water, in inches per season;
 Minimum field-measured applied irrigation water, in inches per season;
 The count of the number of measured fields for specific crop types.
5
Table 1.0: Summary of applied irrigation water for the 1989-1992 period from Appendix B
(Land & Water, 1994)
1989
through
1992
Average
Maximum
Minimum
Count
Alfalfa Alfalfa
/
grass
10.4
6.3
17.7
8.0
2.8
4.0
48
3
Barley
Grass
hay
Grass
Oats
pasture
3.2
6.0
0.0
17
15.5
22.9
9.8
11
14.2
18.1
10.2
2
4.7
8.3
1.8
5
Oats
/
Peas
6.9
9.3
4.5
2
Potatoes Spring Winter
Wheat wheat
10.8
23.5
5.8
9
8.7
16.1
0.0
12
7.2
13.8
0.0
24
Direct review of these tables is very informative in order to understand historic water use. For
the accumulated 1989-1992 period:




Average measured irrigation on alfalfa for the 1989-1992 period was 10.4 inches per season
and peak measured irrigation was 17.7 inches per season;
Average measured irrigation on potatoes for the 1989-1992 period was 10.8 inches per
season and peak measured irrigation water was 23.5 inches per season. This is the highest
recorded irrigation application value listed in Appendix B of the Land & Water report, and as
demonstrated and reported on page 3 and page 6 of the Land & Water report represents
over application of irrigation water;
Average measured irrigation on spring wheat was 8.7 inches per season and the peak
measured irrigation was 16.1 inches per season;
Average measured irrigation on winter wheat was 7.2 inches per season and the maximum
was 13.8 inches per season.
These values are in alignment with other sources of information for applied irrigation water; for
example, the readily available FIIP reported water quotas: Mission Valley average for 19681988 period = 11.3 inches per season with a range from 6 to 15 inches per season; Little
Bitterroot Valley average for 1971-1988 period = 11.5 inches per season with a range from 6 to
17.4 inches per season.
We compare the values above with the River Diversion Allowances for dry water year
conditions (highest stress period) under the proposed Compact as discussed above:



45.4 inches of water (3.78 acre-feet) per irrigated acre to be diverted into the Jocko Valley
when adding inflow from unadministered locations;
20.9 inches of water (1.74 acre-feet) per irrigated acre to be diverted into the Mission Valley
when adding inflow from unadministered locations and increases in Flathead River pumping
allowance of approximately 20,000 acre-feet in a dry year.
23.6 inches of water (1.97 acre-feet) per irrigated acre to be diverted into the Little
Bitterroot Valley in all water year types.
6
Comparison of the magnitude of the historic measured irrigation application volumes
determined by Land & Water and shown in Tables 1.0 and 2.0 to the River Diversion Allowances
under the proposed Compact substantiates that the water allocations in the proposed Compact
are adequate to meet historic irrigation use, and are in direct contrast to statements found in
the Dutton report regarding the proposed Compact’s inability to meet historic irrigation
amounts. This conclusion carries added weight when considering that there is a consistent
pattern in that only 80-85% of the FIIP acreage mapped as active is irrigated in any given year,
further increasing the effective per-acre allowance.
Table 2.0: Summary of applied irrigation water for each year in the 1989-1992 period from
Appendix B (Land & Water, 1994)
1989
Barley
Grass
hay
Grass
Oats
pasture
5.9
6.0
5.8
2
Barley
10.9
12.0
9.8
2
Grass
hay
18.1
18.1
19.1
1
Grass
pasture
6.0
6.0
6
1
Oats
3.1
6.0
0.0
7
Barley
------0
Grass
hay
10.2
10.2
10.2
1
Grass
pasture
3.0
3.0
3.0
1
Oats
Average
Maximum
Minimum
Alfalfa Alfalfa
/
grass
9.0
5.4
14.0
6.8
5.0
4.0
9
2
Alfalfa Alfalfa
/
grass
10.4
8.0
17.7
8.0
2.8
8.0
20
1
Alfalfa Alfalfa
/
grass
10.6
--17.5
--43
---
2.5
3.5
0.0
19.0
22.9
15.5
-------
Count
9
5
4
0
1992
Grass
hay
Grass
Oats
pasture
Average
Alfalfa Alfalfa Barley
/
grass
11.4
--3.0
14.6
---
Maximum
16.2
---
6.0
16.7
Minimum
8.1
---
0.0
Count
10
0
3
Average
Maximum
Minimum
Count
1990
Average
Maximum
Minimum
Count
1991
0
Potatoes Spring Winter
Wheat wheat
5.1
8.3
1.8
Oats
/
Peas
4.5
4.5
4.5
1
Oats
/
Peas
9.3
9.3
9.3
2
Oats
/
Peas
-------
2
12.1
13.5
10.6
2
Potatoes
10.8
16.1
0.0
7
Spring
Wheat
5.7
11.1
0.0
3
Winter
wheat
15.7
23.5
7.8
2
Potatoes
8.2
10.9
5.5
14
Spring
Wheat
7.1
11.9
2.3
1
Winter
wheat
8.2
8.8
7.6
4.4
8.2
0.5
5.8
7.3
3.7
0
2
2
3
Potatoes Spring Winter
Wheat wheat
4.5
Oats
/
Peas
---
8.6
4.3
9.8
---
4.5
---
11.9
4.3
13.8
10.5
---
4.5
---
5.8
4.3
6.3
5
0
1
0
3
1
4
7
Potential Evapotranspiration
The Dutton report, in Section 4.0, provides a review of Potential Evapotranspiration (PET), and
uses this as a basis to report an irrigation water requirement. PET is the sum of evaporation
from a soil surface and plant transpiration, under ideal irrigation management, and if water
availability is not a limiting factor. However, as very clearly documented in the Land & Water
Report, and as early as the detailed Hodges and Kollenborn Reports1, irrigators on the FIIP
operate in a water-supply limited situation and practice deficit irrigation. While PET is a critical
concept in agronomics, it did not form a basis for the negotiations leading to either the 2013 or
2015 proposed Compacts. Water availability is limited on the FIIP, and has been limited on the
FIIP since early in the project’s history.
We note that throughout the Dutton report, there is reference to the observation that
individual irrigators on individual fields were able to achieve high crop yields and irrigate near
potential. This observation is borne out by the findings of the METRIC study, sponsored by the
DNRC. Nothing in the proposed Compact precludes individual irrigators from prioritizing
irrigation to individual fields, from applying re-use water to irrigation, or from moving their
water allocation between tracts within individual RDA areas to achieve these high levels of crop
production
We note that throughout the Dutton report, the author references the requirements for
melons and potatoes and the inability of a farmer to market a partially formed potato or melon
crop. We put these crops in perspective relative to the crop mix on the FIIP:


Based on the 2102 USDA National Agricultural Statistics Survey for Sanders County, there
were 173 acres of vegetables, melons, potatoes, and sweet potatoes grown across all of
Sanders County. If we liberally estimate there are 50 acres of melons grown on the FIIP, this
equals approximately 0.04 % of the irrigated acres on the project;
Based on the 2013 Montana Agricultural Statistics, there were 2,100 acres of potatoes
grown in Lake County, all presumably on the FIIP. This equates to approximately 1.6 % of
the irrigated acres on the project.
The flexibility inherent in the construction of the RDAs in no way precludes higher irrigation
amounts on these higher value, and important crops.
1
P.V. Hodges. 1939, U.S. Indian Irrigation Service Report titled Report on Water Supply of the Flathead Irrigation
Project Montana. H.S. Kollenborn, 1945. Report on Water Supply and Water Use for the Flathead Irrigation Project
Montana. United Stated Department of the Interior Office of Indian Affairs Irrigation Division Agricultural
Economics Unit.
8
Potential Mitigation Section
The Dutton report provides some constructive points in the mitigation section and notes that
these are needed to meet the challenge of serving both instream flows and irrigation water
uses. We concur that this is a challenge and demonstrate, with the points highlighted below,
that the proposed Compact is constructed to accomplish this.










Definition of minimum enforceable instream flows that are well below optimal from a
biological perspective;
Deferral of instream flows while monetary resources are brought to bear to aid the FIIP;
Focus with the State and federal contributions on actions that bring direct benefit to FIIP
operations and overall operational efficiency;
Construction of the FIIP water use right as RDAs, which allow for full flexibility for the
Project Operator and irrigators to manage a defined allocation of water;
Improved and expanded water measurement, strategic on-farm efficiency improvements,
updated water supply forecasting tools, a public website to provide information and
guidance to irrigators, updated water accounting tools , etc…. all to improve Project
operations, leading to water conservation to meet the intent of the proposed Compact;
Definition of the instream flow and irrigation water allocations by wet, normal and dry years
to embed flexibility to adapt to each year’s water supply conditions;
Provision for additional water, and a fund for expanded pumping at the Flathead Pumping
Plant;
Preservation of status quo in instream flows and RDAs in the water-stressed Little Bitterroot
Valley;
Adaptive Management provisions which allow all affected parties to participate in water
management, allow for science-based decision making; and allow for adaptation as climate
change or other factors emerge; and
Shared shortage provisions which clearly outline mitigation procedures to apply during
periods of water shortage.
Conclusions to the Dutton Report
Below we provide a point-by-point discussion of the conclusions to the Dutton synopsis report.

We addressed point 1 under the historic water use, and note that all of the measured
irrigation application amounts in the Land & Water Report are lower than the high number
cited in the Dutton report. In reviewing the entire dataset for all fields – the average
measured irrigation application volume was 8.3 inches per season, the 80th percentile
(lower) measured irrigation application volume was 4.8 inches per season, and the 20th
percentile (higher) irrigation application volume was 13.1 inches per season. The interval
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between 20 and 80 percent constitutes the bulk of the measured irrigation application
values.
The FTA concept embedded in the proposed 2013 Compact was highly unpopular with
irrigators, and the current RDA concept allows full flexibility to distribute water within
irrigated areas and to capture and re-use water derived within an irrigated area following
procedures set forth by the Project Operator and irrigators. We provide the RDA values on a
per-acre basis above, and note that these are diversion amounts are measured at the
source of supply.
We discuss the construction of the RDA levels in the section titled River Diversion
Allowances.
Irrigators who apply greater amounts of water to grow higher value crops are not limited by
the constructs of the proposed Compact, and if they are in an area directly or indirectly
under the sphere of influence of the Flathead Pumping Plant, may seek to increase their
water supply.
Irrigation application near the theoretical potential level is achieved by some irrigators as
documented by the METRIC study. However, on the whole, FIIP is a deficit irrigation project
and irrigation at maximum potential levels has never been achievable across all project
acres.
The proposed Compact is the most viable mechanism to improve project capacity and FIIP
infrastructure. The proposed Compact is constructed so that water savings in the FIIP are
dedicated to instream flows. This is the mechanism to improve instream flow levels, while
preserving historic irrigation water use. The alternative would be to directly reduce
irrigation supply to improve instream flows.
The Dutton report is incorrect to assert that most project acres would not benefit from use
of the Flathead Pumping Plant. Approximately 29% of the project is directly served by the
pumping plant, and acreage throughout the Mission Valley would also indirectly benefit
from this additional water supply because less water would have to be diverted from the
Mission Valley to serve areas served by the pumping plant.
The adaptive management provisions of the proposed Compact provide measures to adjust
for climate change or other issues that may emerge in the future.
The RDA approach to water allocation allows for flexibility in water delivery within the
interior of the FIIP, and emerging crop patterns can be accommodated per Project Operator
and irrigator policy.
The mitigation measures listed in Section 5.0 of the Dutton report along with many others
provided for in the proposed Compact will lead to more beneficial use of the limited water
resource.
The final dire conclusion of the Dutton report is not substantiated and, as noted throughout
our materials above, is not warranted.
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Limitations to the Dutton Report
The Dutton report is based on and draws from a technical report prepared by Land & Water in
1994. This earlier report is a substantial, data-driven contribution to understanding irrigation
water use on the FIIP and reflects the type of work we hope to see go forward under the
Operational Improvements in the proposed Compact. However, we note there are limitations
on applying the Land & Water Report to assert that Historical Water Use will not be met with
FIIP irrigation allocations in the proposed Compact. A sample of these limitations follow:
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The Land & Water (1994) irrigation guide had as an objective to improve energy use and
irrigation water use through irrigation scheduling. This objective differs from a
comprehensive review of historic water use across the approximately 128,500 acres of the
FIIP.
The Report did not look at flood (gravity) irrigated lands. Over 30% of the irrigated acres on
the FIIP are flood irrigated and these lands are not represented in the Land & Water Report.
The Land & Water Report included only three fields that are clearly identified as pasture.
Approximately 60 % of the acres on the FIIP are irrigated pasture, and this crop type is
poorly represented in the field measurement program.
Summary
The 1994 Land & Water Report contains valuable information on historic water use, energy use,
and potential evapotranspiration rates. However, the associated Dutton synopsis report:
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does not accurately describe the field-measured irrigation water use volumes found in the
Land & Water Report;
while clearly recognizing that FIIP is a deficit irrigation project, does a disservice by
determining and reporting irrigation water requirements based on potential
evapotranspiration;
inaccurately asserts that the RDA levels will not meet historic water use levels;
does not accurately characterize the flexibility inherent in the RDA approach to irrigation
water allocation;
does not discuss the substantial positive benefits for irrigation and instream flow water
management that derive from the Adaptive Management provisions;
does not recognize the Shared Shortage provisions in the proposed Compact; and
does not discuss the substantive benefits to irrigators from major State and federal
monetary contributions and the opportunities for enhanced irrigation through the
expanded water supply from the Flathead Pumping Plant.
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