NM Unit Draft EIS Alternatives

The NM Unit draft EIS assesses the potential impacts of the five NM Unit alternatives under consideration, including the No Action Alternative (Alternative A) and four action alternatives (Alternatives B, C, D, and E). Under the No Action Alternative (Alternative A), the NM Unit would not be constructed. If a NM Unit was not built, New Mexico’s rights to access AWSA water would not be legally affected and it is not known how the ISC would vote to use the money in the NM Unit Fund.

The action alternatives are each summarized below by location (i.e., Cliff-Gila, Virden, and San Francisco) and further divided into components at those locations. The project components at each location include the proposed diversion methods and structures, conveyance, storage, wells (if applicable), power, construction, and operations. Maps for each action alternative are also provided below, along with NM Unit analysis area maps and NM Unit land ownership maps.

On October 21, 2019, the Entity sent a letter to the joint lead agencies requesting “…that the joint leads designate Alternative D, the ‘Virden only’ alternative, as the Preferred Alternative in the final EIS. The NM CAP Entity is not requesting a change to its [July 2019] Proposed Action." The joint lead agencies have not identified a preferred alternative in the NM Unit draft EIS.

Comparison of NM Unit alternatives

  • Alternative A—No Action (Total Consumptive Water Use* = 0 acre-feet [AF])

    • NM Unit would not be built, and infrastructure to divert, convey, store, or otherwise support access to AWSA water would not be developed

    • New Mexico’s rights to access AWSA water would remain intact

    • Proposed NM Unit infrastructure would not be built; however, individuals, irrigation districts, and other entities would continue improvement and maintenance of existing facilities (e.g., pushup and permanent diversions and ditches) or propose new facilities under different authorities

  • Alternative B—Entity Proposed Action (Total Consumptive Water Use* = 1,782 AF)

    • Cliff-Gila Location

      • One fixed crest weir diversion with 60-foot-long riffle rundown replacing the existing Upper Gila, Fort West, and Gila Farms Diversions

        Various conveyance improvements and extensions

      • Four new gravity-fed, clay-lined storage ponds (combined surface storage capacity of 1,890 AF)

      • Five production wells, 120 feet deep

    • Virden Location

      • Use existing Sunset and New Model Diversion Structures with no modifications

      • Use existing canals with no modifications

      • Two new clay-lined, gravity-fed storage ponds (combined surface storage of 551 AF)

    • San Francisco Location

      • New fixed crest weir diversion with 20-foot-long engineered fill boulder riffle rundown, replacing the existing Spurgeon and Thomason Flat push-up diversions

      • Various conveyance improvements and extensions

  • Alternative C (Total Consumptive Water Use* = 1,845 AF)

    • Cliff-Gila Location

      • Three rock vane weir semi-permanent diversions (no engineered fill) to replace push-up diversions at the existing Upper Gila, Fort West, and Gila Farms Ditch headings

      • Existing ditch configurations and capacities for conveyance

      • Four gravity-fed, clay-lined storage ponds (combined surface storage of 1,890 AF)

    • Virden Location—Same as Alternative B

    • San Francisco Location

      • One new rock vane diversion to replace the existing Thomason Flat push-up diversion

      • Various conveyance improvements and extensions

      • Earthen embankment dam and unlined reservoir with a storage capacity of 600 AF in Weedy Canyon

  • Alternative D (Total Consumptive Water Use*= 349 AF)

    • Cliff-Gila Location—No project components would be constructed

    • Virden Location—Same as Alternative B

    • San Francisco Location—No project components would be constructed

  • Alternative E (Total Consumptive Water Use* = 1,459 AF)

    • Cliff-Gila Location

      • Pneumatically adjustable Obermeyer gate diversion, replacing the existing Upper Gila Diversion

      • Various conveyance improvements and extensions

      • Two new pump-fed, unlined ponds as aquifer and storage recovery (ASR) basins and surface storage in Winn Canyon (combined surface storage of 1,820 AF)

      • One new gravity-fed clay-lined pond for surface storage in the Cliff-Gila Valley (surface storage of 258 AF)

      • Three ASR wells, 60 feet deep

    • Virden Location—Same as Alternative B

    • San Francisco Location

      • New fixed crest weir diversion with 20-foot-long engineered fill boulder riffle rundown at the existing Spurgeon push-up diversion site, replacing the existing Spurgeon and Thomason Flat push-up diversions

      • Various conveyance improvements and extensions

      • Unlined earthen embankment dam and reservoir with a storage capacity of 1,610 AF in Weedy Canyon

*Total consumptive use is defined as a modeled estimate of the annual average of consumptive use of additional AWSA water including losses to reservoir/pond evaporation, based on CUFA constraints and proposed infrastructure.

NM Unit alternatives maps

The alternatives data are also available here as Google Earth files.

 

For more information on the draft EIS, visit the project website or email NMUnitEIS@empsi.com.

You can also contact Sean Heath at Reclamation (623-773-6250) or Ali Effati at ISC (505-827-5801).

To be added or removed from the mailing list, email NMUnitEIS@empsi.com.