Colorado River System 5-Year Projected Future Conditions

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General Modeling Information

Control Display Icon  Overview

Projections of future conditions of the Colorado River system are updated at least twice annually in January and August. The modeling approach and assumptions are included below along with the results of the most recent projection.

The most recent projection of future Colorado River system conditions was produced in January of 2019.

Control Display Icon  Modeling Approach

The January 2019 projections are developed using a combination of Reclamation reservoir operations models, the Mid-term Operations Model (MTOM) and the Colorado River Simulation System (CRSS) (see General Modeling Information for details). The system conditions for January 2019 through December 2019 are simulated in MTOM and then the end-of-year conditions are imported into CRSS to continue simulating from January 2020 onward. This process utilizes the current Colorado Basin River Forecasting Center (CBRFC) forecast for the potential near-term inflows, and methods to incorporate hydrologic uncertainty resulting in a wide range of plausible future inflows for the mid- to long-term.

MTOM uses 35 potential inflow sequences forecast by the CBRFC that incorporates hydrologic uncertainty by considering current conditions and historical temperature and precipitation patterns.

Each MTOM simulation results in a set of December 2019 system conditions that are used as initial conditions in CRSS. This means initializing CRSS 35 times- once for each set of initial system conditions. Each CRSS initialization is combined with 111 future inflow sequences developed by resampling the 1906-2016 natural flow record using the Index Sequential Method. This results in a total of 3,885 future projections, i.e., traces, for analysis.

Modeling Approach Flow Chart

Modeling Approach Flow Chart

Control Display Icon  Future Projections

CRSS and MTOM model results are reported as the percentage of future projected Lake Powell and Lake Mead operations that are within each operational tier in the next five years. The percentages are computed out of the total 3,885 future projections (i.e., traces), however; the percentages shown may not be representative of the full range of future possibilities that could occur with different modeling assumptions. These operational tiers are depicted in the coordinated operations diagram.

Table 1: Percent of Traces with Event or System Condition. Results from January 2019 MTOM/CRSS using the full natural flow record (1906-2016).
Event or System Condition 2019 2020 2021 2022 2023
Upper Basin - Lake Powell
Equalization Tier 0 1 10 13 17
Equalization - annual release > 8.23 maf 0 1 10 13 17
Equalization - annual release = 8.23 maf 0 0 0 0 0
Upper Elevation Balancing Tier 100 31 42 48 46
Upper Elevation Balancing - annual release > 8.23 maf 43 19 39 44 40
Upper Elevation Balancing - annual release = 8.23 maf 57 11 3 4 6
Upper Elevation Balancing - annual release < 8.23 maf 0 1 0 1 0
Mid-Elevation Release Tier 0 66 42 24 22
Mid-Elevation Release - annual release = 8.23 maf 0 0 0 3 4
Mid-Elevation Release - annual release = 7.48 maf 0 66 42 21 18
Lower Elevation Balancing Tier 0 3 6 15 16
Lower Basin - Lake Mead
Shortage Condition - any amount (Mead <= 1,075 ft) 0 69 82 81 79
Shortage - 1st Level (Mead <= 1,075 and >= 1,050) 0 69 50 33 26
Shortage - 2nd Level (Mead < 1,050 and >= 1,025) 0 0 31 39 31
Shortage - 3rd Level (Mead < 1,025) 0 0 0 9 21
Surplus Condition - any amount (Mead>= 1,145 ft) 0 0 0 1 4
Surplus - Flood Control 0 0 0 0 0
Normal Year or ICS Surplus Condition 100 31 18 17 17

Download Table 1

Archived Tables

Previous tables (starting in January 2012) are also available. Select the date (a new window will open):


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Last updated: 2019-02-06