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  • Writer's pictureMark L. Johnson

Know Your H2O-Part VIII-Central Arizona Project (CAP)

Updated: Jul 11, 2021

Part VIII covers the Central Arizona Project (CAP) including; (1) General Description, (2) Construction, (3) Pumping & Energy, (4) Arizona's Colorado River Water Allocations and (5) Finances/Rates.

In Part VII, we learned how the Law of the River led to Arizona's 2.8 million acre-feet (MAF) allocation of Colorado River water. Here we will cover how that water gets distributed to the cities/towns, farms and Indian lands in Arizona.

Many common water resource terms will be explained but you can go to the Water Lingo Tab for more definitions and information. Reference photos are provided of waterworks facilities constructed and/or managed in CT, IL and CA and from other sources in AZ. Notes[1] containing references and supplemental information are provided at the end of the blog.

Central Arizona Project (CAP)

1.0 General Description

The Central Arizona Project (CAP) was authorized by Congress in 1968. Construction commenced in 1973 and was completed in 1993. CAP was built by the United States Bureau of Reclamation (USBR) and is federally owned. The Central Arizona Water Conservation District (CAWCD) operates and maintains CAP.

CAP includes the following major facilities. See map below.

  • 336-miles concrete aqueduct

  • 14-pump stations

  • 1-Regulating Reservoir-Lake Pleasant

  • 1-Pump/Hydroelectric Facility-Waddell

  • 39-radial gate structures (flow control)

  • 50-turn-outs (customer delivery)

2.0 Construction

CAP includes three major aqueduct divisions that were built in phases; (1) Hayden-Rhodes Aqueduct, (2) Fannin-McFarland Aqueduct and (3) Tucson Aqueduct. [1][2]

Hayden-Rhodes Aqueduct construction started in 1973 and was completed in 1985. This division includes; 4-pumping plants, 6-siphons and 173.6 miles of concrete aqueduct. This got Colorado River water to Phoenix.

Fannin-McFarland Aqueduct construction started in 1981 and was completed in 1987. This division includes; 1-pumping plant, 1-siphon (Gila River) and 57.4 miles of concrete aqueduct. This got Colorado River water closer to Tucson.

Tucson Aqueduct construction started in 1984 and was completed in 1993. This division includes; 9-pumping plants, 1-tunnel and 37.7 miles of concrete aqueduct. This got Colorado River water to Tucson.

The New Waddell Dam was completed in 1992 creating Lake Pleasant which is the CAP regulating reservoir. CAP water is pumped into Lake Pleasant from October to March when water demand is lower and then water is released via a hydroelectric facility to the CAP aqueduct from March to September.[3]

3.0 Pumping & Energy

It is true, water does not flow uphill! The elevation at Lake Havasu (full) on the Colorado River is 450'. The highest elevation at the end of CAP in the Tucson division is about 2,900'. That is a total elevation gain of 2,450' to overcome plus the friction losses in the system. This is why 14 pump stations are required to sequentially lift the water from Lake Havasu to Tucson. See hydraulic profile below. [4]

CAP pump stations and other facilities require a huge amount of electrical power (2.5 million MW-Hrs/Yr). CAP is Arizona's largest power consumer. The energy for CAP originally came from the Navajo Steam Generating Plant (NSGP) near Page, AZ. A 309-mile electrical transmission system was built to transport power from NSGP to all the CAP facilities. In 2019, NSGP was decommissioned and CAP now obtains its power through a Diversified Power Portfolio. CAP annual energy cost ranges between $60-$80 million per year!

4.0 Arizona's Colorado River Water Allocations

In Part VII, we learned that Arizona's annual Colorado River water allocation is 2.8 MAF (per Law of the River with no Drought cut-backs). Now let's see how that water is allocated within Arizona. Please refer to the Table below which shows how the 2.8 MAF flowed through Arizona in 2018.

Here are the key numbers:

  • 2.8 MAF Allocation: 2.63 MAF was actually delivered to Arizona and the remaining 0.17 MAF remained in the Colorado River system as conserved water.

  • 2.63 MAF Delivered To AZ: 1.52 MAF was delivered to CAP and the remaining 1.11 MAF was delivered to 68 entities in Arizona along the Colorado River including farms, Indian lands, Yuma, etc.

  • 1.52 MAF CAP Delivery: delivered to CAP entities as shown below, with Municipal and Industrial (M&I) getting the most at 0.66 MAF.

  • 0.66 MAF CAP M&I: Tucson AMA water utilities are contracted to receive a portion of this M&I amount up to a total of 0.17 MAF as shown.

5.0 Finances/Rates

CAP Capital Cost & Re-Payment Obligation

The total cost to construct CAP was $4.4 billion. Arizona's share of these costs is $1.65 billion and will be re-payed over time. The annual re-payment is $55-59 million. The remaining balance is $1.01 billion and should be paid off in the next 25 years.

CAWCD Refresher

In Part VI-Groundwater, we learned that CAWCD has two divisions; (1) CAP and (2) Central Arizona Groundwater Replenishment District (CAGRD).

CAWCD is responsible for the operation and maintenance of CAP and the re-payment obligation.

CAWCD is also responsible for the operation and maintenance of CAGRD which provides groundwater replenishment for Member Service Areas (MSA) [water utilities] and Member Lands (ML) [subdivisions]. CAGRD provided the scheme to allow growth in areas without access to non-groundwater (Colorado River water & recycled wastewater). MSAs and MLs pay a CAGRD replenishment assessment based on the amount of groundwater used in excess of the Assured Water Supply (AWS) groundwater usage limitations placed on the MSA or ML.

CAWCD Finances

The 2019 CAWCD Audited Financial Report shows total revenues of $399.3 million and total expenses of $305.20 for a change in net position of $94.10 million. Not to shabby! Feel free to review the audited financials but here we will concentrate on Revenue.

Revenue is derived primarily from the sale of water and power, capital and facility-use fees paid by water users and property taxes (Maricopa, Pinal & Pima Counties). For example, residents in Marana contribute to CAP via the property tax bill and the Tucson Water or Marana Water bill as described below.

Property Tax

All property owners in the three counties pay a CAWCD property tax of 14-cents per $100 of assessed valuation. This property tax has two components; (1) 10-cents goes to CAP and (2) 4-cents goes to the Arizona Water Banking Authority (AWBA)[the other groundwater replenishment entity].

Below is a copy of my Marana property tax bill. No worries, the $8,148 assessed value is our first year partial assessment, i.e. we are not living in a hut in the Tortolita Mountains! The tax item labeled "CEN ARIZ WTR SEC" is the CAWCD property tax and is calculated as follows for 2019:

$8,148/100 x $0.14 = $11.41

Water Rate

CAWCD charges its M&I contractors (water utilities) for CAP water deliveries. The 2019-2024 Rate Schedule shows the current M&I rate is $152/AF.

CAWCD charges its CAGRD contractors (water utilities and subdivisions) a Groundwater Replenishment Assessment. The 2019-2024 Rate Schedule shows the current Tucson Active Management Area (TAMA) rate is $736/AF. Yikes! This rate is almost as high as the California State Water Project rate which is actually a more expansive water resource system than CAP.

Water utilities will pass on the CAP charges and any CAGRD charges to its customers. Subdivisions will pass on the CAGRD charges to its residents.

My Tucson Water bill is shown to the left. The CAP charge is $0.70/100 cubic feet.

This rate became effective in July 2019. It is based on Tucson Water's 2017 total CAP purchases of $26,248,318 divided total consumption of 37,453,460 ccf.


  • The Central Arizona Project (CAP) is a remarkable water resource system that provides essential Colorado River water to Maricopa, Pinal and Pima Counties.

  • In 2018, CAP received 1.52 MAF of Arizona's 2.8 MAF Colorado River water allocation.

  • CAP is energy intensive as it includes 14 pump station stations that lift Colorado River water sequentially from Lake Havasu (450') to Tucson (2,900').

  • CAP was built by the United State Bureau of Reclamation (USBR) at a cost of $4.4 billion and is federally-owned.

  • Central Arizona Water Conservation District (CAWCD) operates and maintains CAP and is responsible for the re-payment of Arizona's share of CAP construction ($1.65 billion).

  • CAWC is also responsible for the operation and maintenance of the Central Arizona Groundwater Replenishment District (CAGRD).

  • CAWC obtains a portion of its CAP revenues from a 14-cent property tax in Maricopa, Pinal and Pima Counties. 10-cents goes to CAP and 4-cents goes to the Arizona Water Banking Authority (AWBA).

  • CAWC bills its CAP contractors (water utilities) and CAGRD contractors (water utilities and subdivisions) for water delivered in accordance with approved rate schedules. The water utilities and subdivisions then pass on these costs to its customers and residents, respectively.

CAP is a remarkable water resource facility that has allowed Arizona to grow by replenishing a portion of its aquifers.

Two big questions. Has CAGRD placed an unrealistic demand on CAP? Will CAP Colorado River water allocation be reduced due to Interim Shortage Guidelines and Drought Contingency Plan?


Upcoming Parts include; Tucson Active Management Area (TAMA), Marana Water/Tucson Water & Conclusions



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