Verde Reservoirs Sediment Mitigation Project Feasibility Report and Environmental Impact Statement

Preliminary Alternatives

Photo credit: Kevin Doyle, AECOM

 

Preliminary Proposed Alternatives

Alternative 1—No Action

  • SRP would continue to operate, care for, and maintain the Verde River reservoir system (Bartlett Dam and Horseshoe Dam) as normal under existing contracts, including with current methods of sediment management.

  • No construction would occur under this alternative.

  • Water storage capacity would continue to decrease in Horseshoe and Bartlett reservoirs due to sediment accumulation.

  • No United States Forest Service (USFS) actions would be associated with this alternative. Developed recreation sites would continue to be managed according to current and future management direction.

  • No United States Army Corps of Engineers (USACE) actions would be associated with this alternative.

Alternative 2—New Bartlett Dam and Reservoir Expansion (approximate 1,901-foot Normal Maximum Water Surface Elevation (NMWSE) with Sediment Management Infrastructure

  • This alternative includes construction of a new Bartlett Dam and associated structures, relocation of affected recreation, administrative, and utility infrastructure, and implementation of sluicing operations to move sediment through the Verde River reservoir system.

  • The new Bartlett Dam would expand the reservoir capacity up to 650,122 AF, inclusive of 323,484 AF of additional storage capacity referred to as Bartlett New Verde Space (Bartlett NVS).

  • The new Bartlett Dam design would include sediment sluicing gates via the low-level outlet works to move river sediment through the Verde River reservoirs system.

  • The existing Bartlett Dam would be decommissioned and partially removed.

  • The new Bartlett Dam would increase the NMWSE in Bartlett Reservoir to approximately 1,901 feet, an increase of 101.8 feet in elevation compared with the existing reservoir.

  • Affected recreation, administrative, and utility infrastructure would be relocated in correspondence to Bartlett Reservoir’s NMWSE.

  • There would be a severance and transfer of all existing water rights stored at Horseshoe Reservoir to the new Bartlett Reservoir.

  • Horseshoe Reservoir would continue to operate as a storage reservoir for an estimated additional 108,000 AF of Vacated Horseshoe Space (VHS).

  • New water rights would be acquired under Arizona law for Bartlett NVS and VHS.

  • Upon completion of construction and the Secretary of the Interior transferring operation and maintenance to SRP, SRP would assume the care, operation, and maintenance of the new Bartlett Dam as part of the SRFRP.

  • Under this operation plan, spill out of new Bartlett Dam would decrease in comparison to the No-Action Alternative.

  • SRP would manage the Verde River reservoir system such that more senior water rights would accrue water first.

  • USFS recreation sites and other infrastructure on the Tonto National Forest (TNF) would be relocated to accommodate the new NMWSE.

  • Newly constructed recreation sites would remain in the Tonto Recreation fee system and, consistent with TNF’s Land and Resource Management Plan (LRMP), would employ sustainable operations systems and design to the extent practicable.

  • TNF would issue a new Special Use Permit (SUP) for the operation of a new marina and associated improvements at Bartlett Reservoir .

  • TNF would issue new SUPs for the relocation of all existing authorized uses, including but not limited to the Maricopa County Sheriff’s Office and the communication site provider.

  • TNF would modify the existing SUPs to Arizona Public Service (to reflect their new alignment of the existing 345kV transmission line).

  • The TNF’s LMRP would be amended to reflect changes in the Recreation Opportunity Spectrum and Scenery Management System (ROS/SMS).

  • USACE would need to issue a Clean Water Act Section 404 permit for dam and associated facilities construction.

Alternative 3—New Bartlett Dam and Reservoir Expansion (approximate 1,860-foot NMWSE) with Sediment Management Infrastructure

  • Proposes the same components as Alternative 2 except that it plans the construction of a smaller new Bartlett Dam, a 60.8 ft raise in elevation compared to the existing reservoir.

  • The dam designed for Alternative 3 has the same structural alignment and footprint as the Alternative 2 design.

  • This alternative could provide an estimated 402,422 AF of storage capacity and create approximately 75,784 AF of additional storage capacity (i.e. Bartlett NVS).

  • Affected recreation, administrative, and utility infrastructure around  Bartlett Reservoir would be relocated in correspondence with the NMWSE.  Fewer sites would be affected than under Alternative 2.

  • The new Bartlett Dam would be designed to include sediment sluicing gates via the low-level outlet works.

  • SRP would operate and maintain the Verde River reservoir system as described in Alternative 2.

  • New water rights would be acquired under Arizona law for the additional storage space as described in Alternative 2.

  • USFS and USACE’s Federal Actions would be the same as described for Alternative 2.

Alternative 4—Non-structural Sediment Management Plan

  • Reclamation guidance requires the inclusion of a non-structural alternative in feasibility analysis.

  • SRP would modify its current sediment management plan through alteration of sluicing operations through Horseshoe and Bartlett Dams and implement a maintenance dredging program at Horseshoe Dam.

  • The timing of sluicing operations would be determined based on the forecasting of inflow exceedances above the storage capacity.

  • Maintenance dredging at Horseshoe Reservoir would occur through use of mechanical dredging equipment (excavator and/or crane with clamshell bucket) supplemented by in-the-dry excavation equipment (e.g. excavators, bulldozers, and scrapers) to annually remove approximately 511 AF of sediment from Horseshoe Reservoir over a 100-year period. The dredged material would be relocated by truck to an offsite disposal area.

  • The USFS would identify areas for the replacement of developed campgrounds near Horseshoe Reservoir and motorized trails near the proposed disposal site.

  • The proposed sediment disposal site would require future revisions of USFS’ Motor Vehicle Use Maps and modification of the existing Off-Highway Vehicle Permit Zone.

  • USFS would issue a SUP for the disposal site.

  • USFS would amend the TNF’s LRMP to reflect changes in ROS/SMS due to the relocation of recreation infrastructure and a motorized trail system.

  • USACE would issue a Clean Water Act Section 404 permit for the discharge of dredge material into the Waters of the United States.

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For more information on the VRSMP Feasibility Report and EIS, please visit Reclamation’s project website, or email VRSMP@usbr.gov. If you would like to receive email notifications and updates on the VRSMP, please email VRSMP@usbr.gov with subject line "Add me to Email List.”