Water Conservation and Stormwater Management

VIEWING WATER AS A RESOURCE

The lingering western drought, continued population growth, recent Colorado River water shortage declarations and increasingly unpredictable precipitation patterns underscore the importance of developing a sustainable water supply to address future demand. While Arizona has been proactive in this effort since the 1980s, there is still a lot of work to be done. The District is a regional leader in flood control and stormwater management, and—as the owner/operator of significant flood storage and conveyance facilities—we can play an important role in addressing this critical issue. In response, the District updated its mission statement to include “stormwater is recognized as a resource for the long-term benefit of the community and environment.” This update not only acknowledges the benefits of alternative water management strategies, it reflects the District’s interest and commitment in working with other agencies to help address these regional water challenges.

The District’s Water Resources Program

Assists the District in increasing collaboration with other public agencies and promoting better integrated water resources management. Inter-agency collaboration and acknowledgement of stormwater as a valuable resource are important components of flood risk mitigation.
Provides technical direction and guidance to District staff and consultant teams in the principles and practices of alternative stormwater management and integrated water resources management in the planning, design and construction of District projects.
Manages water resources on-call consultant contracts, water resources projects, studies, and education and outreach; and furthers program development.

LANDSCAPE ARCHITECTURE

Lead Project Management for projects with Landscape Architectural focus

Projects with a landscape architectural focus at the District include projects centered around GI/LID implementation (more on that below), landscape restoration and water conservation. The Durango Site and Landscape Retrofit project is currently the major focus for the District’s Landscape Architecture group. Other projects that are in the works include two efforts related to restoring the trail and open space associated with the ACDC, with a focus on mitigating maintenance headaches for O&M and to restore the aesthetic and functional value of the trail. These projects will serve as early examples of the District utilizing GI/LID as a flood control tool with the ability to provide additional community benefits.

Provide support/perspective to other Planning and Project Management Division (PPM) projects

District landscape architects have a role in nearly all of PPM projects. Since the division handles projects from the early planning stages through construction, the District landscape architects provide support for projects at all stages by working with District planners identifying flood issues and solution development and teaming with project managers through design and construction. The focus is on creating holistic solutions for flood issues which involves combining a wide variety of stakeholder feedback (general public, municipalities, other agencies, elected officials) and an understanding of the environmental conditions that a proposed solution should be sensitive to. Additionally, the team has the ability to speak the language of the more technical disciplines typically involved on a District project, such as hydrologists and a variety of engineers, in order to develop context-sensitive and multi-use flood control solutions. The results speak for themselves – projects have overlapping uses of flood control projects for things like developed open space (public parks/ball fields), natural open space/trails, as well as providing environmental benefits that protect plant and animal life and their natural ecosystems.

Leadership in studying and using GI/LID techniques as stormwater management and flood control in Maricopa County

District landscape architects stay involved in professional practice and academic discussion surrounding the utilization of GI/LID techniques in Arizona. Groups from ASU, U of A, our counterparts in Pima County and others are work together on policy, projects or research to support projects to improve outcomes in the communities we serve and live in. These resources allow the District to stay current on best practices and lessons learned from other projects that can be considered when developing District projects. Our involvement in these meetings also helps the District stand out as a leader in the study, design and implementation of GI/LID in Maricopa County.

GI/LID is a term that summarizes a toolkit of planning, design and construction practices used to mitigate human impacts to the natural environment as a result of development. A major focus of the District’s GI/LID usage is to consider strategies that better manage stormwater resulting in reduced flooding and pollutant/sediment loads. This protects riparian or wetland habitats because it maintains the pre-development hydrologic function. Simply, this allows water to soak into the ground as much as possible before it reaches a drain pipe. When designed properly, implementing these strategies can provide additional benefits to a community like water conservation, aesthetics, heat mitigation, air quality, public open space and reduced dependence on expensive gray infrastructure. GI/LID techniques range from natural solutions such as conservation easements that protect ecological function to simple basins and swales for stormwater management to more engineered solutions such as permeable pavers and water storage/reuse systems. These intervention tiers closely correlate with the amount of available space because natural solutions are the most environmental friendly; however, they also require the most space while the converse is true in that more engineered solutions require less open space.

Established in 2002, the Native Tall Pot Tree Nursery has grown thousands of native Sonoran Desert trees for use on District projects. The nursery is located on the Durango Campus immediately to the west of the Operations and Maintenance Building, within a one-acre fenced enclosure. Current tree production includes eight species of native desert trees (Ironwood, Blue Palo Verde, Foothills Palo Verde, Desert Willow, Velvet Mesquite, Screwbean Mesquite, Whitethorn Acacia and Catclaw Acacia), as well as a capacity to produce some additional desert shrub and riparian tree species (Desert Hackberry, Wolfberry, Graythorn, Creosote, Cottonwood and Gooding’s Willow).

Once a project is completed, construction sites need to be stabilized and site disturbances need to be revegetated. Here in the Sonoran Desert, impacts to native plants and soils are often long-lasting, and sites rarely return to their pre-disturbance condition. As a result, there is a very real need to help nature out and give it a ‘kick start’ by stabilizing site soils, reducing erosion and providing favorable conditions for plant recruitment and establishment. Native seeding and erosion control best management practices, combined with the installation of native tall pot grown trees, can meet this need. This is especially true in remote desert areas or active floodplains. These areas are not appropriate for an irrigation system (nor desired), and continued potable water use is simply not the right course of action.

Many native desert trees produce long tap roots early after germination to seek out limited water sources deep in the arid soils. Propagation techniques at the District’s nursery take advantage of this plant attribute by growing trees in long PVC sleeves (pots) to encourage this growth characteristic. Tall pot plants typically have a greater ‘root-to-shoot’ ratio (more roots than visible above-ground vegetation) that helps to reduce initial stress after installation. This technique also increases the long-term survival without the use of a potable water irrigation system

Using native vegetation and tall pot trees on District projects and properties not only stabilize sites and improve disturbed landscapes, they also enhance the natural and beneficial function of floodplains, riparian corridors, washes and arroyos. Native trees and vegetation stabilize soils, reduce erosion and sediment transport and increase natural infiltration. Additional benefits include: improved air quality, increased wildlife habitat and biodiversity, increased recreational and open space opportunities and increased community quality of life.

WATER CONSERVATION AT THE DURANGO CAMPUS

The District moved to its current location at the Durango Campus when the Administration Building was completed in 1991. Over the last 30 years, landscape improvements and irrigation modifications were minimal and centered primarily on maintenance needs. This left dated landscaping and an aging irrigation system.

With a framework set by the Durango Campus Master Plan from 2017, the District advanced the effort by creating the Durango Campus Landscape and Water Conservation Retrofit Feasibility and Costing Assessment – completed in October 2019. During early stages of the study and concept creation, it was decided that GI/LID features could be located to create a site-wide stormwater management system. In order to achieve the three main goals, the design would need to utilize virtually every drop of water that falls on the District’s property more intentionally. This equates to the design of many, smaller GI/LID features throughout the site.