Introduction
Agua Fria Arial
Aerial View Showing Project Layout

The Agua Fria Recharge Project (AFRP) is a direct recharge project located near the City of Peoria in Maricopa County. It is located approximately 4 miles downstream of New Waddell Dam (Lake Pleasant). The Central Arizona Water Conservation District (CAWCD) developed the project. In 2003 the City of Peoria purchased AFRP storage capacity to support water resources management goals by providing recharge for future population growth.

The facility consists of two operational components: a managed facility consisting of a four mile river section used for recharge and conveyance of surface water downstream, and a constructed facility consisting of a headworks structure to capture surface flow in the river and a conveyance canal to route water downstream to 100 acres of spreading basins.

Together, the managed and constructed facilities provide a total permitted recharge capacity of 100,000 acre feet per year. It is the only recharge project in Arizona to combine streambed recharge and infiltration basins at a single facility. The project operates under two Underground Storage Facility (USF) permits, one for each facility, issued by the Arizona Department of Water Resources (ADWR).

Managed recharge activities began in September 2001, while construction of the recharge basins and associated facilities continued. After completion of the constructed facility in May 2002, both the managed and constructed facilities commenced operation.

Agua Fria Overhead Picture
Recharge Operations at Constructed Facility

Project Facts

  • Hydrologic feasibility assessments and permitting for full-scale facility: 1997 to 1998
  • Construction of basin facility: April 2001 to May 2002
  • Construction cost: $10.5 million
  • Completion date: May 2002.
  • Location: T4N, R1E, Section 6 East ½ (basins only)

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Facility Components

Managed Facility

CAP water is delivered into the low flow channel of the Agua Fria River (managed facility) via a blowoff structure in the Agua Fria Siphon. The inflows are measured using an acoustic flowmeter in the blowoff structure. CAWCD purchased land in the streambed and acquired flowage easements from various state and private landowners to allow use of the river for recharge and conveyance.

Constructed Facility

The constructed facility consists of an earthen dam (headworks structure) to capture surface flows from the river. The water is then conveyed to the spreading basins through a 4,000 feet long, trapezoidal, concrete-lined canal. A broad-crested weir is used to measure flow entering the recharge basins. The constructed facility consists of 7 spreading basins located in an embayment along the river's western terrace (Basins A - G). Water is distributed to each basin from Basin A, a sedimentation basin, which is connected to a distribution channel on the west side of the facility.

Agua Fria Arial View of Facility
Aerial View of Constructed Facility

Concrete outlet structures are used to control deliveries to each basin and to provide grade control along the distribution channel as each basin is progressively lower in elevation southward. Basin A functions primarily as a desiltation basin. It is 14 feet deep with its outlet structure to the distribution channel at a depth of 9 feet. The remaining basins are 6 feet deep. The perimeter and basin divider berms are composed of native soils excavated from onsite, which have been mantled with riprap (cobble size material) to protect them from erosion.

Broad-crested Weir above Recharge Basins
Broad-crested Weir above Recharge Basins

Blowoff Structure Releasing Water into the Agua Fria River
Blowoff Structure Releasing Water into the Agua Fria River

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Operations

Managed recharge operations began in September 2001 with continuous releases from the blowoff structure. Spreading basin recharge began in April 2002 after several of the basins were constructed. Since that time, groundwater mounding beneath both facilities has required wet/dry cycling and strategic use of the recharge basins.

Release into Agua Fria River via Blowoff Structure
Release into Agua Fria River via Blowoff Structure

Basin ponding depths as well as depth-to-groundwater measurements are used to plan and schedule operations and determine the length of wet and dry cycles. Typically, wet cycles range from 3 to 7 days in duration and dry cycles range from 5 to 10 days in duration. When canal maintenance activities require an extended project shut down period, wetting cycles can be extended to 2 to 4 weeks. Occasionally, managed recharge is conducted exclusively to allow groundwater mounding beneath the basins to dissipate.

Infiltration rates for the managed facility (river section) have ranged from 2.7 to 4.3 ft/day with an average rate of 3.85 ft/day. Infiltration rates at the basins have ranged from 1.21 to 3.48 ft/day.

Water Captured from River at Headworks Structure for Delivery to Recharge Basins
Water Captured from River at Headworks Structure for Delivery to Recharge Basins

Typical Spreading Basin Wetting Cycle
Typical Spreading Basin Wetting Cycle

Typical Spreading Basin Wetting Cycle
Typical Spreading Basin Wetting Cycle

Streambed Recharge in the Managed Facility
Streambed Recharge in the Managed Facility

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 Water Deliveries

Water deliveries are scheduled through the CAP Control Center. A Water Storage Permit, issued from the Arizona Department of Water Resources (ADWR), and a Water Storage Agreement with CAWCD are necessary to store at the facility.

Acoustic Flowmeter at Blowoff Structure
Acoustic Flowmeter at Blowoff Structure

Water deliveries are determined monthly using flowmeters at the facility and are reported in acre-feet (AF). One AF is about 326,000 gallons. For the AFRP, an acoustic flowmeter is used to measure deliveries from the blowoff structure to the entire facility. A broad-crested weir measures flow entering the spreading basins. Flow into the managed facility is the difference between the two measurements.

Conveyance of Water to Basins
Conveyance of Water to Basins

Losses are subtracted from the daily delivery volumes to determine the net recharge. At the AFRP, losses consist primarily of evaporations, which is determined using the 1970 Cooley Method. Typical evaporation losses range from 0.5 to 1.0% of the volume delivered for recharge.

Water Moving Down River at 225 cfs
Water Moving Down River at 225 cfs

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