Water is precious in deserts. The excess reclaimed water from the 91st Avenue Wastewater Treatment Plant (WWTP) is a resource that can no longer be ignored. Most of the current reclaimed water from the WWTP is used for agricultural irrigation and industrial purposes, but there is an ever-increasing amount of water going unused. This unused flow, estimated at between 40,000 to 60,000 acre-feet (almost 20 billion gallons of water) per year, is plentiful in the winter and non-existent during the summer. Other communities in Arizona have started to recharge their excess reclaimed water into groundwater aquifers and store it for later use. The Agua Fria Linear Recharge Project (Project) is investigating whether the reclaimed water from 91st Avenue WWTP can be reused or recharged in the Agua Fria River corridor, and if so, supplement the Valley’s water supply, improve river habitat, and provide recreation and education opportunities for residents.
The WWTP owners are called the Sub-regional Operating Group (SROG). SROG is a consortium of cities, including Glendale, Mesa, Phoenix, Scottsdale and Tempe. SROG has been looking at the option of groundwater recharge since 1992. In 1996, SROG and the Federal Bureau of Reclamation agreed to conduct a study that considered a linear recharge model. This model is favored over traditional basin recharge because the impact on any one area is reduced, and the habitat/ recreational opportunities are expanded.
Figure 1 shows the Agua Fria Project study area. Lake Pleasant currently holds the water that would naturally flow in the Agua Fria River.
The Wadell Dam creates an ephemeral stream, yet the casual observer will still see spots of water, vegetation and activity in the River due to discharge from local wastewater treatment plants, storm drains, and sand/gravel operations within the channel. The Project concept involves increasing water-based activities by transporting reclaimed water along the river as far north as Bell Road. The water is then strategically allowed to flow south along a 10-mile stretch of the River. A series of lateral pipelines spaced at approximately one-mile intervals diverts water from the pipeline into the River channel, and allows greater control of how much and where the water is discharged. As the water flows in the streambed, it recharges the aquifers.
This current groundwater recharge model generates many benefits for the Valley. Reclaimed water can be stored in the ground and removed for later use. The reclaimed water actually comes out of the ground cleaner than when it goes in due to a process called Soil Aquifer Treatment. The groundwater table (aquifer) in many places along the River is critically low and experiencing subsidence…the collapse of aquifer materials. Replenishing the groundwater not only helps preserve the aquifer, but SROG generates water recharge credits. These State credits allow withdrawal of water from aquifers at a future date. In some cases, the actual water that is placed in the aquifer can be withdrawn so there is no need to construct extensive pipelines and pumps to deliver the water for direct reuse. In other situations State groundwater credits permit withdrawal from other locations within the Valley.
The overall Project consists of four phases. Phase 1, contacting area residents and stakeholders to solicit their opinions, has already occurred. Phase 2, scheduled to run between October of 2003 and January of 2006, looks at the technical issues of the Project, creates conceptual designs, analyzes the economics of linear recharge, determines the feasibility of options, conducts a formal environmental impact study, and issues a Project report summarizing the results. Phase 3 develops preliminary designs and is set to start January 2006. The final phase (Phase 4) creates a final design and builds the project. If all goes as planned, the Project could be operational by December 2010.
Phase 1 created a Project association made up of approximately 80 people representing over 40 organizations. They conducted stakeholder interviews, completed initial technical analyses, developed a project website, identified data gaps and prepared a consensus plan highlighting the group’s findings. The following summarizes Phase 1 accomplishments and results:
A Project organization was created to assure an inclusive process. The Oversight Committee consisted of agency decision-makers authorized to implement the consensus plan. The Steering Committee, with 61 participants representing 30 agencies and other organizations, assured key stakeholders had a role in the Project planning process, and supported the five (5) Technical Committees. Technical Committees, [including Flood Control (FCTC), Habitat and Cultural Resources (HCRTC), Public Involvement (PITC), Recreation (RTC) and Water Resources (WRTC)] collected and analyzed information, and prepared technical summaries for each issue area.
The first six months of Phase 1 were spent identifying stakeholders, public concerns, and technical /regulatory issues. Meetings were scheduled with 25 organizations, and interviews conducted with 50 individuals. 9,800 project newsletters were distributed, and two public meetings held to gather input from the public. From all this input the Project team assembled the common themes that the technical committees used to focus their research.
Themes coming from the Flood Control Technical Committee (FCTC) included 1) the impact of recharge on groundwater, 2) reclaimed water quality, 3) groundwater mounding, 4) salinity, 5) impacts on other River operations, 6) mosquitoes and insects, 7) odor, 8) alternative uses for the water, 9) bird strike hazards on aviation, and 10) the economic and social benefits of the Project to surrounding communities. Other comments addressed coordination of the Project with the Maricopa County Flood Control District Agua Fria Watercourse Master Plan, the impact of the Project on flood control and storm water conveyance, regulatory compliance, landfills, storm water/recharge integration, coordination with sand and gravel operations, and maintenance of the streambeds.
The Habitat and Cultural Resources Technical Committee (HCRTC) determined their focus would be creating, restoring and augmenting habitat within Watercourse Master Plan. The HCRTC learned that the quantity and seasonal nature of the available water will impact the level of habitat restoration, and recommended recharge locations be integrated with existing water discharge points. Public concerns included mosquito management and bird air strike hazards.
The Public Involvement Technical Committee (PITC) identified people and organizations needing a voice in the planning process. PITC determined the issues and concerns to be addressed by the other technical committees, produced and distributed the project newsletter, developed the website, and assured clear communication between the public and the Project.
The Recreation Technical Committee (RTC) created options for integrating recreational uses into the Project. Philosophically, education and recreation opportunities should be designed into the recharge and habitat features to serve multiple purposes. Collaboration with other River plans and with the Friends of the West Valley Recreation Corridor is vital. The RTC suggested pipeline locations, river interpretive programs, and recreation easements for open space dedicated to public access. They also recommended ways to balance recreation with flood control safety and habitat preservation.
The Water Resources Technical Committee (WRTC) identified the opportunities and challenges of recharge along the River. In doing so they looked at source water availability, water quality, hydrogeologic impacts, design/operation, and permitting. Comments from the public and key stakeholders reinforced the need for the WRTC to look hard at the pre-recharge treatment processes that remove contaminants. With current technology the WRTC determined that the quality of 91st Avenue WWTP reclaimed water is comparable to untreated surface water sources, and that through soil aquifer treatment (SAT) and natural groundwater blending the recovered water would be classified A+ by State standards. Current groundwater quality would not be adversely affected. In some Project areas where currently the groundwater contains high levels of metals, fluoride, sulfate, and background nitrates, recharged water would actually improve the groundwater quality. However, already high mineral content (TDS) in the groundwater could be a problem for the Project.
The specific recommendations of the five technical committees, the Steering Committee and the Oversight Committee are given in detail as part of the Phase 1 Consensus Plan. Spirited interaction between the five technical committees to identify and resolve concerns early in the discussions benefited the Project.
The Consensus Plan assembles in one document a wealth of information obtained from stakeholders and the Steering/technical committees. Contained in the Consensus Plan are the building blocks for developing additional Project alternatives, the technical Project parameters, and recommendations for Project design and operation. To help with understanding, the Project has produced a compact disk containing the Consensus Plan including the map files and the complete final reports of all five technical committees.
Phase 1 of the Project achieved all its goals and demonstrated that a linear recharge project in the River is feasible, and in conformance with the Agua Fria Watercourse Master Plan. There is sufficient water available for both recharge and the development of habitat and recreations facilities. The quality of the 91st Avenue WWTP reclaimed water meets established standards. The public involvement process successfully provided the community information about the Project, and gathered concerns and suggestions from stakeholders. Phase 1 produced recommendations and design guidelines that will prove invaluable as the Project moves forward with Phase 2.
Beginning in September 2001, interviews were conducted with representatives of interest groups, neighborhoods and organizations adjacent to the Agua Fria River or associated with other projects being proposed for the river to identify and issues or questions that should be studied by the technical committees.
The following eight key issues identified during the interviews.
What is the problem or opportunity that is trying to be addressed? It is unclear if this is a recharge project or a habitat project or both. Because the boundaries of the project are unclear, some of the impacts to adjacent uses were unknown.
There are a large number of projects currently under study or being implemented in the Agua Fria riverbed or banks that involve some type of water component. Other projects identified by interviewees include:
The issue of collective impacts is somewhat tied to the coordination issues, but focuses more on the collective impacts of the multiple recharge and habitat projects on the groundwater table.
What is the quality of "reclaimed" water? Residents are concerned with the odor and possibility of attracting mosquitoes. This issue was the most important to residents adjacent to the river and the water suppliers with groundwater wells in the study area.
Although past studies have determined that recharge is the best use of the excess reclaimed water because it is primarily available in the winter when most reclaimed water uses have high summer demand, a couple of stakeholders weren't sure that recharge was the best use of this excess water.
Several comments were received about the potential design of the recharge project.
The impact to sand and gravel operations has been obvious throughout the data collection phase. Sand and gravel operations seem to be clustered in various areas of the river where there are not adjacent residential communities. The highest concentration is on the West Side of the river between Olive Avenue and Camelback Road. Another cluster is north of the study area between Beardsley and Rose Garden Lane. Also, Vulcan mines most of the river from Bell to Thunderbird roads.
Who benefits from the project and who owns the water?