San Juan Recovery Implementation Program

NOTE: Hydrology Pages are currently Under Construction

The San Juan Recovery Implementation Program Hydrology Committee provides oversight regarding the hydrologic data and models used by the SJRIP.  The San Juan Basin Hydrology Model simulates flow in the San Juan River below Navajo Dam on a daily time-step.  The primary purpose of the model is to support San Juan River Recovery Implementation Program goals to recover populations of the endangered razorback sucker and Colorado pikeminnow in the San Juan River while proceeding with water development in the Basin.  The model is used in Endangered Species Act section 7 consultations to determine the level of impact, if any, of a proposed action that deplete river flows on the Reclamation’s ability to meet the flow recommendations below Navajo Reservoir.  Note that model results are not the sole criteria used to determine the level of a proposed project’s impact and that model assumptions and model uncertainty are considered when interpreting results.  The SJBHM was used to evaluate and develop the current flow recommendations and will be used in developing future revisions to the flow recommendations.  In addition, the model will be used to develop and evaluate the revised hydrologic baseline.  The model currently uses natural flow data based on historic depletions (1929-2006); however, alternative inflow hydrologies may be evaluated in the future to evaluate current and/or future water availability under different climate change scenarios.

The Bureau of Reclamation is primarily responsible for the development and maintenance of the SJBHM. As of September 2009, the SJBHM is currently being revised. This work is expected to take until December 2010 for the full integration of a new hydrologic baseline. Projected milestones for this and other future model work will be posted soon.

San Juan Basin Background

The San Juan River Basin drains an area of approximately 25,000 square miles, an area equal to that of West Virginia. About 39 percent of the drainage is in New Mexico, 23 percent in Colorado, 20 percent in Arizona, and 17 percent in Utah. The San Juan River is the second largest tributary to the Colorado River. Its source is on the Continental Divide in southern Colorado, and it flows approximately 350 river miles westerly to its confluence with Lake Powell.

Elevations vary from about 3,700 feet above sea level at the confluence with Lake Powell to over 14,000 feet on the crests of mountain peaks in the San Juan range. Precipitation varies from more than 60 inches annually in small areas along the high peaks, to less than 10 inches in extensive parts of the Basin, to less than one-tenth inch in others.

San Juan Recovery Implementation Program Background

The purpose of the San Juan River Basin Recovery Implementation Program is to protect and recover endangered fishes in the San Juan River basin while water development proceeds in compliance with all applicable Federal and State laws. Endangered species include the Pikeminnow (formerly known as the Colorado Squawfish), or Ptychocheilus Lucius, and the Razorback Sucker, or Xyrauchen Texanus. It is anticipated that actions taken under this Program also will provide benefits to other native fishes in the basin and prevent them from becoming endangered in the future.

NOTE: Hydrology Pages are currently Under Construction

SJRIP Model Description

The San Juan Basin Hydrology Model is currently being revised. The technical aspects of the model revison (i.e., getting the model to run with the new changes) are expected to be completed December 2009. Model validation and verification as well as incorporation of a revised hydrologic baseline is projected to be completed December 2010.

The San Juan Basin Hydrology Model is actually a collection of hydrologic models that are used together to model streamflow on the San Juan River. The hydrology model is in its third generation of evolution. Previous generations of the hydrology model were used in the development of flow recommendations and in Environmental Impact Statements (EIS) in the San Juan Riverbasin. Previous versions of the model are available upon request.

The San Juan Basin Hydrology Model simulates flow in the San Juan River below Navajo Dam on a daily time-step.  The primary purpose of the model is to support San Juan River Recovery Implementation Program goals to recover populations of the endangered razorback sucker and Colorado pikeminnow in the San Juan River while proceeding with water development in the Basin.  The model is used in Endangered Species Act section 7 consultations to determine the level of impact, if any, of a proposed action that deplete river flows on the Reclamation’s ability to meet the flow recommendations below Navajo Reservoir.  Note that model results are not the sole criteria used to determine the level of a proposed project’s impact and that model assumptions and model uncertainty are considered when interpreting results.  The SJBHM was used to evaluate and develop the current flow recommendations and will be used in developing future revisions to the flow recommendations.  In addition, the model will be used to develop and evaluate the revised hydrologic baseline.  The model currently uses natural flow data based on historic depletions (1929-2006); however, alternative inflow hydrologies may be evaluated in the future to evaluate current and/or future water availability under different climate change scenarios.

The SJBHM, like any hydrologic model, has error and uncertainty associated with it.  Sources of error include historical data, uncertainty about future inflows or depletions, and error in hydrologic methods selection. The SJBHM is not a water rights model and does not attempt to accurately model individual water rights.  Rather, the focus of the SJBHM is to accurately simulate the daily flow below Navajo Reservoir.  Model assumptions and error are evaluated to determine their net impact on the accuracy of daily flows below Navajo.

Reclamation is responsible for maintaining and improving the SJBHM and making model runs at the request of the Fish and Wildlife Service and the SJRIP Coordination Committee.  Reclamation is also responsible for maintaining and updating SJBHM documentation.  Model documentation and information are available on the SJRIP Hydrology Committee webpages.

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NOTE: Hydrology Pages are currently Under Construction

SJRIP Scenario Model Runs

This page is reserved for the description and results of model runs that will take place in the future. Future runs may include validation runs for the revised generation three model, revised hydrologic baseline scenario runs, revised flow recommendations runs, and any future section 7 consultation runs.

In the past, the San Juan Hydrology Basin Model has been used to analyze three major hydrologic studies which are the NIIP Consulation, the Animas LaPlata Supplemental Environmental Impact Study, and the Navajo Enviromental Impact Study. NIIP Consulation runs were made with first generation models and rulesets. ALP SEIS and NEIS runs were made with second generations models and rulesets. These models and rulesets are available upon request.

 

NOTE: Hydrology Pages are currently Under Construction

This page is reserved for the data and accompanying documentation used in the SJBHM.Future data will include depletion data, climate data, naturalized flow data, historic flow data, etc.

 

San Juan Recovery Implementation Program - San Juan River Basin

 

Map: San Juan Basin (4 corners area, the basin extends into CO, UT, AZ, & NM.
Last Updated: 2/22/17