»Ê¹ÚÌåÓýappÏÂÔØ

Introduction

Image Details

Riparian ecosystems provide many important benefits to people and nature, but are often negatively impacted by development and urbanization. Pima County’s Floodplain and Erosion Hazard Management Ordinance No. 2010-FC5 (the Ordinance) requires builders and developers to mitigate for “unavoidable� destruction of riparian riparian
Definition of riparian habitat or riparian areas.

Learn more about riparian areas. For off-site mitigation, Pima County Regional Flood Control District (the District) collects fees from building and development permittees prior to issuing a permit. The District uses the mitigation fees to plan, implement, and design projects in riparian ecosystems that deliver multiple benefits. 

The Ordinance governs how and where development occurs in conjunction with zoning. The District’s mitigation guidelines emphasize preservation of riparian habitat and avoidance of adverse impacts wherever possible. Where impacts cannot be feasibly avoided on a building or development project, project permittees may mitigate through actions on-site, such as replanting native vegetation. Where on-site mitigation is not an option, the District allows off-site mitigation. 

The Ordinance allows the District to prioritize the use of funds from off-site mitigation fees to maximize benefits on county lands.The District may use mitigation fees to restore riparian habitat, provide land stewardship, and acquire land, water rights, and conservation easements. Stewardship and restoration efforts focus on promoting native plants, or plants with historic cultural value. Project areas are often designed to accommodate visitation by the public.  

Safeguarding riparian ecosystem function and services through vegetation management is an important aspect of sound floodplain management for minimizing flood risk and erosion. The District is a regional agency whose mission is to protect the health, safety, and welfare of Pima County residents by providing comprehensive flood protection programs and floodplain management services. The Ordinance promotes stable floodplain functioning by preserving and enhancing riparian vegetation. These services emphasize fiscal responsibility, protection of natural resources, and a balanced multi-objective approach to managing regional watercourses, floodplains, and stormwater resources. 

Key Issues Addressed

Riparian ecosystems are threatened by unsustainable development, industrial pollution, groundwater withdrawal, and prolonged drought. Although the Clean Water Act (CWA) protects major watercourses, it does not necessarily cover the entire floodplain or other areas important for watershed function. The Ordinance provides an additional layer of protection that includes several types of riparian ecosystems. This approach promotes stable floodplain functioning with native vegetation that slows flood flows, provides erosion protection for river banks, and improves water quality. Projects are designed to support wildlife that might be stressed by urbanization, including invertebrates and pollinators, and to provide resources for migratory birds. 

In addition to the Ordinance, Section 404 of the CWA requires builders, utilities, developers and others to mitigate for impacts on Waters of the U.S., as defined in the CWA. Although there is some overlap, there are key differences. The Ordinance includes a broader range of defined types of riparian ecosystems that generally includes more of the floodplain and surrounding vegetation. It is designed to keep people out of erosion hazard areas and from increasing flood risk in Pima County. While Section 404 is also about public safety, it primarily serves to maintain the country’s major watercourses and water quality through protection of defined channels and adjacent wetlands. 

Project Goals

• Oversee Ordinance compliance; collect permit fees and use them to fund priority mitigation projects in unincorporated Pima County
• Provide stormwater management and flood control through preservation and restoration of riparian ecosystems
• Meet multiple safety, ecological, economic, and social objectives through mitigation

Project Highlights

Success in Unlikely Places: The District’s restoration projects have been successful overall despite drought and heavy impacts from previous land uses. At Swan Wetlands, the restoration site was once a landfill. 

• Land Acquisition: The Ordinance in-lieu riparian mitigation fee has allowed the District to acquire 700 acres of land with riparian habitat, such as a recent acquisition in the Brawley Wash area with high-value riparian characteristics along the Santa Cruz River and land in the San Pedro River Watershed.
• Restoration: Through the ordinance, permit in-lieu fees cover installation of native plants and maintenance, including watering and irrigation for a minimum of 5 years or until riparian vegetation has been successfully established. For on-site mitigation on commercial projects, developers are required to do the 5-years of maintenance and irrigation as well as annual monitoring.
• Partnerships: The District’s restoration and flood control projects have provided opportunities for the District to work with Army Corps of Engineers (ACE), the federal agency charged with overseeing compliance with the CWA Section 404 permits. Other partners including Arizona Game and Fish Department and US Bureau of Land Management.
• Regional Planning: The protection to riparian ecosystems that the Ordinance originally provided was integrated into a regional effort to develop the Sonoran Desert Conservation Plan (SDCP). SDCP includes a Conservation Lands System, and Multiple Species Conservation Plan for compliance under the federal Endangered Species Act. Covering a 2 million-acre planning area, SDCP seeks to maintain riparian ecosystems as a key component for improving habitat connectivity for multiple wildlife species.
• Classification and Mapping of Riparian Areas: In October 2005, the county adopted an updated system of classifying and mapping riparian ecosystem types. The Riparian Classification Maps were a result from studies performed for the development of the SDCP. This system allows for clear definitions and mitigation standards appropriate for each type.
• Restoration for Multiple Benefits: Restoration sites provide flood control and habitat for many wildlife species. They also provide many public health benefits by providing green space for recreation, improved water quality, adaptation to increasing temperatures by minimizing the heat island effect caused by urbanization, and by providing outdoor venues for environmental education. One restoration site includes community gardens for a local high school and community foodbank. Property values are improved where restoration sites are transformed from barren land to green space.

Lessons Learned

Image Details

• Implementing the Ordinance has encouraged preservation of habitat by informing people of the value of their land. After learning about the Ordinance, permittees often prefer to adjust their plans to avoid impacts that would require mitigation.
• Preservation of open space can benefit both builders and residents. People like to buy houses next to preserved areas and are willing to pay premiums. Close proximity to open space is good for property values. Project permittees can save money because they are aware of what permitting requirements may or may not be applicable on a given piece of land from the very beginning of their project.
• The mitigation fees acquired through the Ordinance have contributed funds to multiple projects in Pima County.
  • Pond and site renovations at  to make more efficient use of water, plant native species, remove invasive plants, create new wildlife habitat, and create educational opportunities.
  • At , the District planted 11,000 plants on 400 acres, created ponds for toad habitat, and created habitat for lizards, ants, and bats.
  • Acquisition of  in the San Pedro Watershed mitigation fees including contributed of $488,000 of riparian in-lieu fees of the total purchase of $1.55 million for 3,200 acres of riparian habitat.
• Enforcing the Ordinance has allowed the District to learn how to run the program to accomplish the goals of preservation and enhancement of riparian vegetation and floodplain functionality.
• The Ordinance creates a regulatory framework that ultimately streamlines the permitting process. When permittees apply for a 404 permit, they can put as a condition that they have met the requirement of the Ordinance. Mitigation for the the Ordinance may be equal to or greater than what would be required for the 404 permit.
• The Ordinance helps the county save money. Buildings and development are more concentrated, allowing roads to be designed for maximum efficiency to facilitate County services (sheriff, emergency vehicles, road maintenance etc), and resulting in less disturbance to the landscape overall.
• The combination of running the off-site mitigation program through the Ordinance, designing and implementing successful restoration projects, and collaboration with ACE on projects has helped the District prepare a proposal to develop a in-lieu fee program to mitigate for impacts under Section 404 of the Clean Water Act within the jurisdiction of ACE. 

Next Steps

• Apply to ACE to develop an in-lieu fee (ILF) program for mitigation under Section 404 of the CWA. Authorized by the CWA, the ACE requires mitigation for damage to aquatic resources. Section 404 provides an option for compensatory mitigation for offsite mitigation through in-lieu fee programs. State and local governments or non-profit organizations can apply to ACE to make their own restoration site a property to receive mitigation funds from Section 404 permits. Sponsoring an ILF mitigation program allows for a third party (e.g. the District) to mitigate damages on behalf of permittees, which offers another mechanism by which funding can be acquired for projects.
• Develop lands associated with , which is currently a park listed on the National Register of Historic Places, as an ILF mitigation property. Funded in part with Ordinance mitigation fees, the District recently restored a  that provides wildlife viewing opportunities, habitat for wildlife, and will be used for irrigating a restoration project. The District has plans to install 30 acres of new riparian and grassland plantings along the Santa Cruz River at Canoa Ranch with the goal of eventually completing a total of 120 acres, and to create a cienega (a wet meadow type of wetland) and pollinator garden. When completed, the project will increase wildlife habitat and connectivity between mountain ranges, and recreational value.

Resources

• in Pima County
• Clean Water Act: 
• . 2008.

Contact

• Suzanne Shields, Pima County Flood Control District: [email protected]

Case Study Lead Author

• Amanda Webb, CART Research Specialist, University of Arizona

Suggested Citation

Webb, A., D. (2019). “Riparian Habitat Protection and Restoration Through Compensatory Mitigation in Pima County, Arizona.â€� CART. Retrieved from /project/compensatory-mitigation-pima-county.