Overview

The goal of the Planning and Development Division (PDD) is to promote prevention of flood-related damage by conducting detailed studies to delineate regulatory floodplains, by encouraging avoidance of floodprone areas through land use and other planning efforts, and by reviewing proposed land development projects for conformance with the floodplain Ordinance. PDD assists commercial and multi-family residential project planners in avoiding floodprone and erosion hazard areas.  By overseeing land use planning and development for flood control concerns, PDD helps assure that growth and development in unincorporated Pima County conform to the development standards of the Floodplain Ordinance. In addition, PDD performs public outreach to ensure that owners of floodprone property are aware of the hazards and provides guidance to reduce flood risks to people or property.

PDD customers are primarily developers, engineers and other County departments. We provide services through:

• Long Range Planning
• Basin and Watershed Management Studies
• Development Review
• FEMA Floodplain Mapping Coordination

Long Range Planning

Through the application of sound floodplain management principles during the planning process, PDD achieves substantial flood hazard prevention before specific development is proposed or lot densities are established. These principles are applied during the County’s Comprehensive Plan Amendment and Rezoning processes, as well as through courtesy reviews of projects in neighboring jurisdictions including Marana, Oro Valley, Sahuarita, the City of Tucson and adjacent counties. In addition, PDD reviews State Land Permit Applications, minor land subdivision applications, variance requests, and other requests in order to ensure that these proposals are compatible with the Ordinance. Staff is available to meet with applicants to ensure that proposed development conforms to sound floodplain management principles.

Another component of PDD is coordinating the long range plan for the District. Under the umbrella of the Community Rating System (CRS), the tasks and functions of the District are evaluated in order to determine their effectiveness. To date, this has resulted in the District’s CRS rating of Class 5 (PDF format) by FEMA.

Basin and Watershed Management Studies

In support of the planning effort, the District analyzes flood hazards within individual watersheds. These analyses, called basin management plans, evaluate the existing floodplain characteristics including riparian habitat, the adequacy of a watercourse to convey the base flood, the flood damage potential to existing development, and the impact that potential new development would have on these conditions. By performing a basin management plan, all parties have a better understanding of the constraints that land management and flooding present to development. Data from these plans are used to make informed land-use decisions and protects both people and property in and adjacent to areas of flooding and riparian habitat.

An example of such a study is a project with the U.S. Geological Survey (USGS) to assess debris flow hazards, a little studied but significant flood hazard. The results of this ongoing study may impact how flood hazards are assessed and delineated by accounting for sediment build-up, and may lead to modification of our operation and maintenance procedures to ensure sufficient capacity in our major watercourses.

Another example is a major Basin Management Study southeast of Tucson in the Lee Moore Wash area. The Lee Moore Wash area is expected to be an area of growth, and this study will be used to create “Rules of Development” within the area.

Due to the impact that a basin management study has on land-use decisions, the District constantly strives to ensure that these plans incorporate reasonable assumptions in the hydrologic and hydraulic models through the use of Technical Policies. For this reason, the District has provided guidance on the use of accepted methods to determine peak flow rates and floodplain mapping. For example, the District requires the use of PC HYDRO V-5 for small watersheds and allows the use of models with routing capabilities, such as HEC-1 or HEC-HMS for large watercourses.

Development Review

Development Review staff review subdivision and commercial development proposals which have been submitted through the Subdivision Development Review process established by Pima County Development Services.

Development Review staff evaluate the completeness and correctness of the Hydrologic and Hydraulic Analysis (PDF format) for the development proposal.  Reviews also include ensuring the development is in conformance with all applicable rules, policies and procedures. Please visit the Development Review page for additional details of requirements and services provided.

FEMA Floodplain Mapping Coordination

Through the National Flood Insurance Program (NFIP), Federal law requires the purchase of flood insurance for structures within a Special Flood Hazard Area (SFHA) as identified on FEMA-issued Flood Insurance Rate Maps (FIRMs) when the property is purchased using federally-secured mortgages, loans, grants, etc. SFHAs are areas determined to be affected by 100-year floods (the flood that has a 1-percent-annual chance of occurring in any given year). (Within FEMA Other Flood Areas and District mapped floodplains, flood insurance optional but is highly recommended.) PDD works with FEMA to ensure that information provided on the FIRMS to the public is correct. All known regulatory floodplains can be viewed for your property on a Flood Hazard Map. FEMA floodplain maps also can be obtained from the FEMA Flood Map Store.

The District is mandated to ensure that new development within an SFHA is constructed to FEMA standards. In order to do this effectively, the District strives update the FIRMS with the best available information. Updates or revisions to the FIRMS often occur when new development alters the floodplain, or when new technical information, such detailed topography, is available to analyze a watercourse more accurately. PDD staff reviews applications to revise floodplain designations submitted by property owners and developers. While map revision requests are reviewed and approved by FEMA, an applicant is required to get the District’s acknowledgement of any request for a Letter of Map Revision (LOMR) in unincorporated Pima County prior to submittal to FEMA.