The Pima people (also known as the Akimel O’otham, or “river people”) have lived in the Gila River Valley of south-central Arizona for thousands of years. In the latter 18th century, they were joined by the Maricopa (also known as the Pee Posh, meaning “the people”) and confederated together. While they had separate cultures and languages, the two tribes agreed to ally and to share the same land. Over the course of the 19th and 20th centuries, however, the settlement of Arizona by nontribal people and the upstream diversion of the waters of the Gila River deprived the Pima-Maricopa people of their water supplies, leading to hunger and the loss of their independent self-government. Over the course of the 20th century, these wrongs have slowly begun to be righted. The use of a federal law called Indian Self-Governance in the 1990s allowed the Pima-Maricopa people of the Gila River Indian Community to assume control of the rehabilitation and construction of the federal irrigation infrastructure on the reservation via a tribal program known as the Pima-Maricopa Irrigation Project (P-MIP).


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Kris Polly: Tell us about your background and how you came to be in your current position.

David DeJong: By background, I am a political historian of American Indian law and policy. My PhD dissertation at the University of Arizona focused on Indian water rights, The new Casa Blanca Canal siphon under the Little Gila River in 2017. specifically those of the Gila River Indian Community. I have researched and written on the history of irrigation and agriculture here in the community for about 35 years. In 2000, I had the good fortune to be hired as project coordinator for P-MIP. In May 2006, when P-MIP’s director retired, I was asked to fill the position and have been in it every since.

Kris Polly: Please give us an overview of P-MIP and its history.

The paving of the 14-foot-bottom Pima Lateral.The new canal has a capacity of 1,300 cubic feet per second (cfs).The canal was originally constructed in 1925; P-MIP improved the canal in 2014-15.

David DeJong: The project originated in the early 1990s,
as the community was negotiating a comprehensive water settlement, but agriculture in this community goes back thousands of years. By the mid-19th century, the Pima- Maricopa people were farming in excess of 15,000 acres. As nontribal settlement in the area expanded during the latter 1860s and 1870s, the Gila River was diverted upstream, reducing water downstream and creating difficult conditions on the reservation. By the turn of the 20th century, the people were literally starving. Newspapers around the country reported on the deprivation and there was a concerted effort as early as the late 1890s to do something to restore the water. But the wheels of justice turn slowly, and nowhere did the wheels turn more slowly than at Gila River.

In 1925, the community finally was able to sue in the federal courts. The Gila Decree, which was issued in 1935, recognized a community entitlement of 210,000 acre-feet of water off the Gila River, but upstream growers were able to keep the water that they were then using, which the community always felt belonged to it. In 1935, the federal district court recognized that the Pima-Maricopa people had an immemorial right to the waters of the Gila River, and as such, that water is delivered to the reservation at no cost, with the U.S. government paying for all the operations, maintenance, and repairs (OM&R) through the Bureau of Indian Affairs’ (BIA) San Carlos Irrigation Project.

As a result of all that, in the late 1940s, the community sued the United States again due to insufficient water. That lawsuit lingered for decades. Finally, in the late 1980s, the community put together a master plan for agricultural and water use on the reservation and identified a water budget. In 1990, the Salt River Project (SRP), the community’s largest and most influential partner, agreed to sit down and negotiate with it and with 34 other parties. In short order, the parties established a framework for the water settlement. It included an annual community water budget of 653,500 acre- feet. At that point, the community and the Bureau of Reclamation began discussing constructing the Central Arizona Project (CAP) Indian Distribution Division to deliver CAP contracted water to and across the reservation. Reclamation, as the federal entity charged with constructing the CAP, was in charge of the project, but the community wanted control. In 1994, Congress amended the Indian Self-Determination Act to create something called Indian Self-Governance, which allows tribal nations to take over programs of the Department of the Interior and operate them themselves. The Gila River Indian Community immediately began to negotiate a self-governance contract, and on October 1, 1995, the community entered into its first annual funding agreement with Reclamation, putting the CAP Indian Distribution Division under tribal control. The tribe renamed it the Pima-Maricopa Irrigation Project.

Beginning in October 1995, the community began to contract with a number of architectural and engineering firms to start the planning process for a system that would deliver all that settlement water to and across the reservation. P-MIP brought four engineering firms under master contracts. The first 3 years were dedicated
to environmental work, planning, and initial design. In 1998, P-MIP started the first reach of construction. It has now constructed over $425 million worth of infrastructure on the reservation, including 135 miles of new irrigation conveyance system and structures, including both concrete-lined ditches and pipelines. It includes a state- of-the-art supervisory control and data acquisition (SCADA) system that we are continuing to build each year. About 65 check structures and turnouts are on SCADA already; more will be added in coming years.

P-MIP is responsible not only for constructing the system but also for all the design, for which we have contracted with four engineering firms. Right now, we have about 120 miles of design completed and next year we will complete the remaining 35 miles. We have acquired nearly $12 million worth of right of way in the last 20 years and we have a small amount of right of way yet to complete. We are also responsible for complying with the National Environmental Policy Act (NEPA) and Section 106 of the National Historic Preservation Act, which deals with cultural resources. We do all the latter through the community, which has its own Cultural Resources Management Program. We contract for all the NEPA work with outside contractors. However, P-MIP does not operate or maintain any of irrigation system. Once we complete the design and construction of each phase of the project, we turn it over to the operators. If it’s part of the existing BIA irrigation system, we turn it over to the San Carlos Irrigation Project (SCIP). If it is not part of the BIA system, we turn it over to the community, which operates and maintains the system through the Gila River Indian Irrigation and Drainage District (GRIIDD), managed by community member Ron Allison. The last year of funding in our long-term contract with Interior is 2029, so sometime in 2030, when all the construction is completed and all the canals have been turned back over to the operators, P-MIP will disband and cease to exist.

Kris Polly: How does P-MIP fit into the tribal governance system?

David DeJong: P-MIP is part of the tribal governance system, and all its employees are tribal employees. P-MIP has a staff of 34 people. About 22 of those are Native American, with about half either Pima or Maricopa. The rest of us are non-native. The community has worked hard to restore its self-governance. During the 19th and early 20th centuries, tribal governments were decimated, and the BIA took control of nearly everything. Tribes were not able to operate programs or deliver services themselves. In recent decades, that has changed. What P-MIP and the community more broadly are doing is engaging in nation-building.

Kris Polly: How big is your service area and what is its population?

A 132-inch siphon on the 750-cfs Santan Canal.

David DeJong: The Gila River Indian Community’s reservation covers about 372,000 acres. Of that, about 201,000 acres is considered irrigable farmland under the practicably irrigable acreage doctrine established by the 1963 Arizona v. California Supreme Court decision. Based on that calculation of irrigable land, the community’s initial water claim was 1.5 million acre-feet. The community ultimately settled for 653,500 acre-feet.

Of the total area of the reservation, about 75,000 acres have been irrigated at one time or another. P-MIP has been charged by the tribal council to design and construct an irrigation system that will ultimately be able to serve up to 90,000 acres of land. Based on our groundwater modeling, we believe that the maximum sustainable acreage is in the 77,000-acre range, but during especially wet years, we might be able to irrigate 90,000 acres. Our goal is to construct a system that will deliver water to 90,000 acres, with 77,000 acres being the projected average on any given year.

Today, we are irrigating only about 32,000 acres, which is 6,000 acres more than were being irrigated in 2009. We are working closely with GRIIDD to identify lands that can be irrigated in the near future. In 2015 and again in 2017, the tribal council approved 5-year water plans in which it identified targeted numbers of acres that it would like to see developed. Around 1,200–1,500 acres are going into agricultural production each year.

Kris Polly: How has P-MIP affected the reservation and its economy over the last 20 years?

David DeJong: The tribe has experienced many changes over the past 25 years, and not only because of P-MIP. Gila River is a gaming tribe and opened its first casino in 1992. The resulting transformation has been nothing short of phenomenal. Twenty-five years ago, only around 7,500 people lived on the reservation. Today, it’s double that. The Pima-Maricopa combined population is about 23,000, and a little over 14,000 now live on the reservation. In the last 25 years, around 1,500 new homes have been constructed on the reservation. The casinos employ 4,000–5,000 people, a good percentage of whom are tribal members. The tribal government employs about 1,500 people, around two-thirds of whom are Native American. In 1992, there was no fire department, and police protection was provided by the BIA, which was understaffed. Today, the tribe has its own Gila River Police Department as well as fire stations all across the reservation. There is not only a new hospital, Hohokam Memorial Hospital, right here in Sacaton, but there are also ambulatory centers across the reservation.

Regarding irrigation water, while the laterals and sublaterals have not yet been completed, P-MIP is constructing the last piece of the backbone system right now. We have a $47.5 million contract with Coffman Specialties to complete the last 6 miles of the backbone system. When that piece is completed later this year, we will be able to take water all the way across the reservation. Historically, the irrigation system that the BIA constructed between the 1910s and 1930s was not large enough to deliver water to all tribal lands. For instance, the tribe has water rights under the Gila Decree for the 50,546 acres of land that can be served by the Gila River, but it has never irrigated more than 35,000 of those acres because of a lack of infrastructure. Our state-of-the-art system will remedy that. Because of P-MIP’s technical skills, a number of tribal departments have spun off from P-MIP, including the surveyors, GIS and Cultural Resource Management Program.

Kris Polly: Where does the community’s water come from?

David DeJong: The Gila River Indian Community, under the Arizona Water Settlements Act of 2004, agreed to limit its annual water budget to 653,500 acre- feet. We have nine different sources of water. Ordered from largest to smallest by the rolling 10-year average volume they provide, they are CAP Indian priority water (191,200 acre-feet); groundwater (173,700 acre-feet); surface water from the Gila River (125,000 acre-feet); CAP non-Indian ag water, originally contracted by CAP to non-Indian agricultural purposes but reassigned to the tribe under the water settlement (120,600 acre-feet); Salt River water provided by the SRP (20,000 acre-feet); A+ reclaimed water provided by the Cities of Chandler (6,730 acre-feet) and Mesa (5,870 acre-feet); Haggard Decree water on the far western end of the reservation (5,900 acre-feet); and Salt River water provided by the Roosevelt Water Conservation District (4,500 acre-feet). Some of these sources are geographically limited, for instance available only on the north or south side of the river. We model the input from each of these nine water sources, which allows us to see what’s happening with the groundwater table. We also monitor water quality.

The price of water varies by source. Gila River water is paid for by the U.S. government, meaning that it is free; CAP water costs about $158 an acre-foot (although under the Water Settlement Act, the United States pays fixed OM&R costs of about $96 an acre-foot); groundwater is $34–35 an acre-foot; SRP water runs about $20; and the reclaimed water that we get from the Cities of Mesa and Chandler is free. In order to be economical, we want to deliver the lowest-cost water the shortest distance possible and apply it to the lands best situated to receive it. CAP water is used as a buffer if there’s a shortage of water from another source. A good portion of it is recharged into the aquifer as a hedge against future shortages.

Managed Aquifer Recharge site 1B on the Gila River Indian Community reservation.This is the second recharge site on the reservation and will store 20,000 acre-feet per year.

Kris Polly: What is your vision for the future of P-MIP?

David DeJong: Whether you come into the reservation from the north or south, you come up over low-lying mountains and then look down into the valley. Historically, people saw a ribbon of green meandering through the middle of the reservation: the flowing Gila River, surrounded by a gallery of cottonwood, willow, and mesquite trees and thousands of acres of agricultural land.

Our vision for the community and the community’s vision for itself is that green ribbon will once again demarcate the community as agricultural lands expand. Since 1982, two-thirds of the agricultural lands of Maricopa County, north of the reservation, have gone out of production and been urbanized. The same is true of 51 percent of the agricultural lands in Pinal County, south of the reservation. As the agricultural regions of the Salt River Valley, the Gila River Valley, and the Casa Grande Valley urbanize, the community wants to pick up those ag lands and become the breadbasket of Arizona as it once was.

Historically, throughout a good portion of the middle and latter parts of the 19th century, the reservation was known as the breadbasket of Arizona, supplying all the foodstuffs for the mining operations in north-central Arizona, all the way down into Tucson and into northern Mexico. The community has historically grown a lot of durum wheat, with most of it going to Italy—you probably have eaten pasta that had its roots at Gila River. The Gila River Farms has a large citrus orchard. All that citrus has been marketed under the label Pima Gold, and much of it ends up in Japan. The community envisions a day when it is sending agricultural produce all across the world and it becomes the breadbasket once again.

David DeJong is the director of the Pima Maricopa Irrigation Project. He can be contacted at or (520) 562-6742. For more about P-MIP, visit