UPPER RIO GRANDE WATER OPERATIONS MODEL

1
UPPER RIO GRANDE WATER OPERATIONS MODEL

• PROPOSED
• RIO GRANDE COMPACT
• ACCOUNTING RULES
• For
• PLANNING MODEL

2
URGWOM RG Compact Accounting Rules

• Upper Rio Grande Basin Water Operations Review
  will evaluate water operations alternatives.
• URGWOM will be used to evaluate these
  alternatives
• Must simulate rules and constraints, including
  those of the Rio Grande Compact,
• Analyze the effect of alternative operating
  strategies on Rio Grande Compact deliveries over
  the long term.

3
URGWOM RG Compact Accounting Rules (Continued)

• Reservoir operating rules, in the form of
  ifthen logic statements, have been developed
  for all major reservoirs in NM.
• Rules for upstream reservoirs are based on
  storage conditions in Elephant Butte and Caballo
  Reservoirs and are important to the evaluation of
  any future operating scenarios.

4
URGWOM RG Compact Accounting Rules (Continued)

• Planning model must be able to determine the
  amount of usable water and credit water in
  Project Storage (Elephant Butte and Caballo
  Reservoirs).
• The determination of amount of water in Project
  Storage will allow the model to perform
  accounting of
• Article I determination of Actual or
  Hypothetical Spill or
• Article VII limitation on storage in reservoirs
  constructed after 1929 when the content of
  Project Storage is less than 400,000 acre-feet.

5
URGWOM RG Compact Accounting Rules (Continued)

• In order to determine the amount of Project
  Storage, release of water from Elephant Butte
  Reservoir must be known.
• Short term (1-year) can be estimated and input to
  model
• Long term release cannot be reliably estimated.
• Therefore, certain assumptions are proposed to
  account for storage and release of water from
  Elephant Butte and Caballo Reservoirs and for
  accounting of accrued debits and credits.

6
URGWOM RG Compact Accounting Rules (Continued)

• Colorado
• Since the Rio Grande basin in Colorado is not
  modeled, the actual annual delivery by Colorado
  in relation to scheduled delivery would be a
  fixed amount, as suggested by Colorado.
• Accrued debits or credits will be determined each
  year on January 1st , which when considered with
  the NM credit/debit status, will determine Usable
  Water and Credit Water (if any) in storage.

7
URGWOM RG Compact Accounting Rules (Continued)

• New Mexico
• On January 1st of each year, the Compact
  schedules will be applied for the previous year
  to determine annual debit or credit.
• Annual credit or debit will be added to accrued
  status to determine current accrued debit/credit
  status.
• The NM accrued debit/credit status will be used,
  along with the CO accrued delivery status, for
  the determination of current Project Storage and
  Credit Water (if any).

8
URGWOM RG Compact Accounting Rules (Continued)

• Elephant Butte Reservoir
• Model will include a slot to input a value of a
  minimum pool in Elephant Butte Reservoir of
  between 0 and 50 KAF. Rule would not allow
  storage in the Reservoir to fall below this
  amount.

9
URGWOM RG Compact Accounting Rules (Continued)

• Elephant Butte Reservoir (continued)
• On March 1st of each year, the model will use
  current amount of water in Project Storage and
  the forecasted inflow to estimate Usable Water in
  Project Storage.
• If this estimated value is equal to or greater
  than 790 KAF plus the amount of the minimum pool,
  790 KAF will be released.
• If less than 790 KAF, release will be reduced on
  a proportional basis.
• Daily releases will be based on historical
  release pattern.

10
URGWOM RG Compact Accounting Rules (Continued)

• Elephant Butte Reservoir (continued)
• If water in storage in Elephant Butte exceeds the
  prudent flood space (50 KAF from April through
  September and 25 KAF from October through March),
  flood control operation rules will govern the
  releases.
• No consideration of release of water for power
  generation.

11
URGWOM RG Compact Accounting Rules (Concluded)

• Caballo Reservoir
• No minimum pool.
• Flood control rules will set release when in
  flood control space (100 KAF)
• Releases will be based on
• Historic relationship between Caballo releases
  and Elephant Butte releases (to take into account
  Caballo Reservoir evaporation).
• Zero release during non-irrigation season.

12
UPPER RIO GRANDE WATER OPERATIONS MODEL

• PROPOSED
• RIO GRANDE COMPACT
• ACCOUNTING RULES
• For
• PLANNING MODEL