I. INTRODUCTION
The Bear River Commission's Procedures for Lower Division Water Delivery,
to which this document is appended, provide for the description of an accounting
method which can be used to account for the distribution of Lower Division
main stem Bear River flows, including accounting of stored water, without
regard to state line, pursuant to the water delivery schedule(s) set forth
in Appendix C (see definitions found in III.C. of these Procedures). The
purpose for describing the accounting method is to document the necessary
logic and approach for water distribution and delivery calculations. The
method described below is based upon appropriate hydrologic and water right
accounting and distribution principles and upon provisions found within
both the Dietrich and Kimball Decrees.
Upon the declaration of a water emergency, the administration of water
deliveries will proceed as needed between the Commission and the States
of Idaho and Utah and their respective river commissioners or watermasters.
Both the States of Idaho and Utah will use their respective computer accounting
models which implement the same methodologies as described below. In order
to protect water users, the states will provide timely diversion measurements
and regulation with weekly reporting to the Engineer-Manager as described
in Section VII of the Procedures for Lower Division Water Delivery.
II. ACCOUNTING
During a Commission declared water emergency, the distribution and delivery
of natural flows will be made to users within Idaho and Utah by priority
and without regard to the state line. It is recognized that during much
of the irrigation season, stored water releases from Bear Lake have a dramatic
impact to the main stem Bear River flows in the Lower Division. It is further
recognized that Utah Power controls these releases within restraints provided
for by the Compact and under state water law to deliver stored water to
contract users. The recognition of these contract holders and the segregation
of stored water from the natural flow is vital to water accounting and
delivery. Therefore, in a water emergency, the following will apply:
A. In order to properly account for water travel times and stored water
delivery losses, the river will be divided into a series of reaches. Reaches
are defined based upon available stream flow information and/or between
points on the river where there are changes in hydrology, including at
major points of diversion or tributary confluences. Once the reaches are
defined, the natural flow gain (or loss as a negative gain) within the
reach is calculated. The natural flow gain within a given reach is defined
as the discharge from the reach, plus any diversions within the reach,
minus the inflow to the reach, plus or minus changes in reservoir contents
within the reach. Reach gains and natural flows available for diversion
within each reach will be calculated and distributions will be made to
users diverting under water rights for non-hydropower purposes set forth
in Appendix C (Water Delivery Schedule No. 1) within that reach and downstream
reaches, by priority.
B. Once all of the natural flow has been distributed, all junior rights
will be distributed zero natural flow. If in the distribution process there
is only sufficient natural flow to meet a portion of the rights with identical
priorities, then distribution will be made on an equal percentage of the
available natural flow to each right holder with the identical priority.
C. Main stem water users will be allowed diversions of stored water
upon receipt by the Commission from Utah Power of storage allocations for
that year in acre-feet by storage contract holder. The storage allocations
provided by Utah Power may reflect the total storage limitations agreed
to in the Bear Lake Settlement Agreement.(1)
D. To properly account for use of all stored water from
Bear Lake, a calculation of natural flow diversions and use of stored water
released from Bear Lake will be made beginning on the date during the irrigation
season when stored water was first released from Bear Lake.
E. Individual stored water use accounts will be tracked
during the remainder of the water emergency and once the stored water allocated
to an individual water user is fully used, the water user will not be allowed
additional diversions of stored water unless the Commission receives notice
from Utah Power that supplemental storage allocations have been made.
F. As provided for in the Dietrich Decree, "in order to
compensate for the natural yield of the Bear Lake area," water released
from Bear Lake shall include an amount of water to be "regarded as 'natural
flow'" in the following amounts during the year:
50 cfs from April 20th to July 1st,
35 cfs from July 1st to July 15th,
25 cfs from July 15th to August 1st, and
15 cfs from August 1st to September 15th.
G. Stored water released from Bear Lake will be subject
to transit losses as provided for in the Dietrich and Kimball Decrees so
as to protect natural-flow water rights. The decreed transit losses are
as follows: 1½ percent of the stored water flowing from the Bear
Lake outlet works to above Grace Dam and an additional 1 percent transit
loss for stored water remaining between each of the following points: Grace
Dam and the diversion for West Cache Canal; between the diversion for West
Cache Canal and the Idaho-Utah State Line; and between the Idaho-Utah State
Line and Cutler Reservoir.
H. The movement of natural flow and stored water within
the system will be subject to travel time as provided for generally in
the Dietrich and Kimball Decrees. It has been determined that the travel
time from Outlet Canal to Corinne is approximately 5 days. Therefore, the
travel time used in the accounting models will be different from the travel
time identified in the decrees.
I. A summation of total natural flow and stored water
available for diversion by reach will be made and the appropriate division
and regulation of such flows within the reaches will be the responsibilities
of the states and their respective river commissioners or watermasters.
III. DISTRIBUTION
An integrated water delivery schedule of all Bear River
Lower Division main stem water rights deliverable in both Idaho and Utah
has been created and incorporated into the states' computer accounting
models. During a water emergency, the states will provide timely diversion
measurements and regulation with weekly reporting to the Engineer-Manager
as described in Section VII of the Procedures for Lower Division Water
Delivery. The following will apply:
A. Natural flow will be distributed according to priority
of rights on the main stem Bear River in the Lower Division, based on Water
Delivery Schedule No. 1 set forth in Appendix C.
B. Stored water from Bear Lake will be accounted for and
distributed to storage water contract holders up to their contracted amount
provided by Utah Power.
C. Tributary streams will be administered by state officials
having jurisdiction in Idaho and Utah.
D. It is recognized that groundwater diversions have an effect on the flows of the Bear River. The States of Idaho and Utah are evaluating this impact, and a list of all groundwater rights with flow rates greater than 0.10 cfs has been prepared by the two states. Additional studies have been and are being performed by the states. Both states are committed to include appropriate groundwater effects in their water accounting and administration.
1. The Bear Lake Settlement Agreement is an agreement entered into on April 10, 1995 between PacifiCorp, the "Bear Lake Group," and the "Irrigators."