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Low Impact Development

The Pima County Regional Flood Control District has begun an effort to coordinate policy decisions about Low Impact Development (LID) and Green Infrastructure (GI) practices for stormwater within Pima County.  An initial Planning Committee composed of water resources professionals from the Pima County Regional Flood Control District (RFCD), Pima Association of Governments (PAG), City of Tucson (COT) Office of Conservation and Sustainable Development, Watershed Management Group (WMG) and GeoSystems Analysis, Inc., formed to initiate a dialogue among local and regional jurisdictions about the management of LID and GI practices within our semi-arid environment.  Looking at LID and GI in semi-arid climates is necessary because the main body of literature and policy has originated in wetter climates in the eastern United States.  This effort continues through the LID Working Group which includes members of local jurisdictions, the consulting community and non-profit organizations.

LID/GI practices for stormwater can be used to improve water quality, lower urban temperatures and reduce potable water consumption.  These practices reduce stress on traditional stormwater  infrastructure and restore natural drainage with a variety of stacked benefits for the environment.  Although different disciplines may not have formally applied practices in the name of LID, examples of LID include technologies that improve infiltration, enhance or maintain vegetation, and/or capture and reuse stormwater.  On a large scale, LID/GI practices emphasize the preservation and restoration of natural landscape features.  On a small scale, LID/GI practices may include porous pavements, infiltration planters, onsite rainwater harvesting or stormwater harvesting/capture in public rights-of-way, open spaces or common areas.

This page provides information about the efforts being undertaken by the District.

Below are links to items relevant to the Districts effort to coordinate LID/GI practices in Pima County.  Many of the documents presented are in Adobe PDF file format.  If you have not already done so, you will first need to download and install Adobe System’s free Acrobat Reader software to view the documents.

An article in the ASCE Source newsletter highlights the work that Pima County has performed.

LID Working Group

The LID Working Group is an ad-hoc group of government, private and non-profit stakeholders formed to support the development of LID/GI in our region.  Initially, it worked to develop guidance and prepare case studies which were two needs identified in the March 15, 2011 LID Workshop held by the Pima County Regional Flood Control District.

The LID working group helped develop a Resolution Supporting Low Impact Development and Green Infrastructure that was passed by the Pima Association of Governments (PAG) Regional Council on June 14, 2012. 

The LID Working Group meets every other month.  For more information contact Evan Canfield.

Low Impact Development and Green Infrastructure Guidance Manual

In the semi-arid climate of Pima County, Arizona, rainwater and stormwater are valuable resources that have many beneficial uses, but have historically been disposed of as a nuisance and a hazard.  The concept of LID/GI encompasses an approach to stormwater management that preserves or mimics the natural drainage of stormwater runoff to mitigate the effects of increased impervious surfaces.  As part of Phase II of the City/County Water and Wastewater Study, an evaluation of the best approach for using rainwater and stormwater as a supplemental water source concluded that capture and use at the lot and neighborhood scale result in the best opportunities. 

The final Low Impact Development and Green Infrastructure Guidance Manual provides non-regulatory technical guidance for implementing neighborhood-scale water harvesting, Green Infrastructure and Low Impact Development (LID/GI) Practices throughout Pima County to improve surface water quality. This manual is intended to be technical guidance for professionals on the use of neighborhood-scale low impact development practices within Pima County, the City of Tucson and similar areas in the desert Southwest.

Cost Benefit Study

Pima County Regional Flood Control District (RFCD) and Pima Association of Government (PAG) contracted with Impact Infrastructure, LLC and Stantec to beta test AutoCASE™ in arid southwest region. AutoCASE™ is currently in the beta stage of testing for stormwater infrastructure. AutoCASE™ analysis provides a comprehensive assessment and takes a broad perspective, looking at the value to the community, government, and the environment. The analysis makes the case that these investments pay back in more than cash terms, and the benefits cited above all have value to a wide range of stakeholders. The project team collected data and calibrated the tool specifically for arid southwest region. The report demonstrates that the approach used in AutoCASE™ can calculate comprehensively defined value using regionally specific values and that the calculations can be run inexpensively as the design changes.

Final report


Business Case Evaluator Spreadsheets (BCE)

  • BCE spreadsheets for the eight practices, and two clusters in the report can be obtained from Evan Canfield.


LID/GI Case Studies

The Pima County Regional Flood Control District (RFCD) is compiling Case Studies reflecting design solutions embracing the evolving mandate for sustainable design: Low Impact Development (LID) and Green Infrastructure (GI) practices. The Case Studies show local projects that use LID/GI practices.  The Case Studies can be used to help groups, professionals or individuals learn more about the value of LID/GI development, what worked, lessons learned, etc.

LID Case Studies Inventory Map

You can create your own self guided tour of the sites mentioned in the above report using the LID Case Studies map created by Pima Association of Governments which can be viewed through Avenza PDF Maps, an offline map viewer for your mobile device.
  1. Download the free Avenza PDF Maps app from Google Play or the Apple App Store.
  2. Open the Avenza PDF Maps app and go to Maps. Click on “+" to import map
  3. Paste http://www.pagregion.com/LIDMap to “From the Web” to import LID Case Studies Inventory Map. 

Create Your Own Case Study

Thank you for your interest in sharing your project and creating a case study for others to follow.  Below you will find documents to help guide you through the process of creating a case study.  Please begin by downloading How To Create a Case Study.  Please use the Case Study Report Outline (Microsoft Word format) template so that the format of your report is consistent with other case studies.

The following Case Study summary templates (Microsoft Excel format) are provided for your convenience based on the project type: