The District's planning program emphasizes a regional, uniform, and coordinated approach to watershed management. This approach works to minimize the public cost of protecting citizens from flooding resulting from private and public development's cumulative effects on drainage characteristics.
The first step toward an independent planning function began with the initiation of Area Drainage Master Studies (ADMSs) in 1983. This was intended to regulate development and establish plans and drainage criteria for implementation by the development community. In 1989, planning was first identified as a separate and distinct District program. In support of the District's mission, this program plans and facilitates implementation of flood control projects that reduce flooding hazards, while balancing schedule, cost and social and environmental considerations. A second important goal of the Planning Program is to identify potential flood control and stormwater management problems prior to the onset of new development. The objective of this goal, through sound planning, is to avoid or minimize the future need for publicly funded structural flood control projects.
The District's Planning Branch prepares comprehensive studies and analyses; identifies locations and property at risk from potential flooding; and identifies regional flood control facilities that will be required in growth areas. Following an analysis of existing and future flooding problems, alternative solutions are developed to determine the most cost effective and publicly acceptable projects. Recommended projects are then prioritized for inclusion in the District's Capital Improvement Program. Non-structural alternatives are also evaluated and recommended.
The District's planning activities are integrated with the regulatory and floodplain delineation activities. Information developed by the Planning Branch is utilized for completing floodplain delineations and regulating new developments. Conversely, the Planning Branch utilizes information developed in the regulatory and floodplain delineation activities.
Activities in the Planning Program include: Area Drainage Master Studies (ADMSs) and Master Plans (ADMPs); Watercourse Master Plans (WCMPs); site specific plans; project pre-design studies; and the coordination of interagency cooperative projects and agreements.
Area Drainage Master Studies
Area Drainage Master Studies (ADMSs) were originally conceived in 1983 to provide technical information to define and quantify flood hazards. Authority for these studies is found in the Floodplain and Drainage Regulations for Maricopa County. The enormity of the ADMS program required that the county be divided into smaller study areas. The ADMS study areas were identified by first establishing the watershed boundaries, and then subdividing these to arrive at study areas that could reasonably be completed. There are forty-eight ADMS areas established from the watershed boundaries, ranging in size from 15 to 580 square miles. The areas with known flooding and with existing and expected development or population growth are given priority.
The purpose of the ADMS is to identify existing flood-prone areas as well as projections of future conditions. The information obtained is then used to identify areas, which require flood mitigation, and to guide future development. To identify flood hazards, a series of tools such as computer rainfall-runoff models, topographic mapping, soils data developed by the National Resource Conservation Service, and land use data developed by the Maricopa Association of Governments are used.
Area Drainage Master Plans
Area Drainage Master Plans (ADMPs) recommend strategies to mitigate the flood hazards identified in a preceding ADMS. The major components of the ADMP include public involvement, biological and archeological assessments, landscape character assessment, inventory of known hazardous waste sites, engineering analysis and cost estimates for alternative flood protection facilities, evaluation of multi-use potential, and detailed engineering analyses of the recommended project features. The District's objective is to integrate these components to develop a solution that is cost effective, provides a high level of flood protection, and avoids impacting natural and cultural resources to the maximum extent practicable.
In recent years, the planning program has been accelerated to get ahead of development. A goal of the District is to complete ADMPs for the entire developable portion of the County by 2015 subject to available funds.
Watercourse Master Plans
ARS §48-3609.01 authorizes the District to perform Watercourse Master Plans (WCMPs). These plans are similar to the ADMS/ADMP program but focused on watercourses rather than watersheds. The primary goal of the WCMP is to provide information and develop solutions that protect existing and future residents from possible damages associated with floods up to and including the 100-year event. In addition, minimization of future expenditures of public funds for flood control and emergency management is of paramount importance.
The intent of the WCMP is to bring together the public, the business community, property owners, and concerned agencies for the purpose of identifying flood hazards and mitigation solutions. These plans incorporate identified unique characteristics that should be preserved, and plan for ongoing uses - both commercial and recreational, which are often neglected in traditional floodplain management. Often, disregarding these issues can result in construction of expensive structural solutions to solve flooding problems.
WCMPs develop and identify alternative plans for the provision of flood control. Traditional structural flood control alternatives are compared to non-structural flood control alternatives. Selected solutions are based upon the river system hydrology, hydraulics, lateral migration potentials, and sediment trends. An important objective of the District is to provide opportunities for multiple uses including recreation, groundwater recharge, riparian habitat preservation or restoration, and other related enhancements. These goals would be implemented by others providing they are consistent with the District's flood control mission. The non-structural flood control alternatives of floodplain delineation, building restriction ordinances, and floodplain acquisition programs supplement traditional structural floodplain management. The District's objective is to partner with the sand and gravel industry and other property owners to develop plans and implementation strategies that are mutually beneficial.
The updated status of current and previous District planning projects is available on the Projects & Structures page.