Project Details

Gillespie Area Drainage Master Study

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Past Public Meetings

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Project Contact: Christopher DiMaggio
Region: SW
District: 4 - Clint L. Hickman 5 - Steve Gallardo

The District initiated the Gillespie Area Drainage Master Study (ADMS) in 2010. The purpose of the Gillespie ADMS is two-fold: 1) Identify and quantify flooding problems and flood hazards by developing a hydrology and sediment model for the watershed and 2) Establish development and infrastructure maintenance guidelines to ensure public safety for residents and property owners in the study area.

Phase I of the Gillespie ADMS studied about 148 square miles of southwestern Maricopa County, including portions of the Town of Gila Bend, the Woolsey Flood Protection District (WFPD) and portions of the City of Buckeye. Based on the results of the modeling, the study team recommended mitigation strategies to address flooding issues that could impact existing and future development.

In 2017, the District initiated Phase II of the ADMS, covering an additional 160 square miles adjacent to and south of Phase I including portions of the Town of Gila Bend and the WFPD. Initial work assignments focused on collecting data about topography and storm water drainage as well as the development of recommendations for flood hazard mitigation measures.


Recently completed work assignments for Phase II focused on developing an integrated 1D/2D hydrologic analysis and preparing a Flood Hazard Assessment Report to aid in the development of best practices for operations and maintenance for ongoing flood hazard mitigation throughout the study area.

Available Documents

Document Name Type Size
Flood Hazard Assessment report PDF
Gillespie ADMS Phase I map PDF
Gillespie ADMS Phase II map PDF

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