Santa Cruz County Line to Pima Mine Rd.
The District has prepared a detailed flood map using a cutting-edge hydraulic model for floodplain mapping, allowing the District and stakeholders to better understand flood risk in this highly complex flood area. This project began a new phase of updating the FEMA floodplain maps in September, 2020 for this reach of the Santa Cruz River.
Pima Mine Rd. to Grant Rd.
The District has removed sediment and improved conveyance from Silverlake Rd to Grant Rd. The District has collaborated with the City of Tucson on the Santa Cruz Heritage Project. The District also cut notches in the grade control structures in the Heritage Reach in order to focus the flows where they can sustain improved habitat.
Grant Rd. to Pinal County Line (Trico Rd.)
The purpose of this phase of the project is to develop a management strategy to balance flood risk management, drainage infrastructure protection, water recharge, recreation, education opportunities, and riparian habitat preservation for the Santa Cruz River from Grant Road to Trico Road.
CONTENTS
Phase 1 – This phase, initiated in February 2018 and completed in October was devoted to existing conditions assessment. Three reports were prepared during this phase:
- Existing Conditions Report – This report documents drainage complaints, land ownership, maintenance responsibility, previous studies and projects that have been done in this part of the Santa Cruz River.
- Infrastructure Assessment and Maintenance Evaluation Report – This report evaluated the state of infrastructure in the Santa Cruz including the state of the soil cement bank protection and conveyance capacity of the River in a 100-yr flood.
- Technical Data Support Notebook for floodplain mapping – This report identified the flood risks along the corridor associated with the 1% annual chance (100-yr) flood and 0.2% chance (500-yr) flood.
The findings of these three reports were used to understand baseline conditions for three sub-reaches of the Santa Cruz River because of the distinctive condition of each sub-reach.
- Grant Rd to Ina Rd Sub-Reach
- Ina Rd to Avra Valley Rd Sub-Reach
- Avra Valley Rd to Trico Rd Sub-Reach
The District will collaborate heavily with the affected jurisdictions, and presented the results of Phase 1 to the Marana Town Council in a study session on September 24, 2019.
Phase 2 – Development of recommended alternatives and an implementation plan. Phase 2 began in October, 2019, and all reports have now been completed.
1) An Alternatives Selection Report was developed which summarizes how alternatives were identified, provides a conceptual design for the alternative, and gives an estimated cost of each project.
2) The Implementation Plan, identifies potential phasing of each of the proposed projects in the Alternative Selection Report, and identifies potential funding sources.
3) The Summary Report describes the entire process and how the reports are used collectively to identify a path forward. This report includes a Public Engagement Report and Stakeholder Engagement Report as Appendices.
Background
The Lower Santa Cruz River in northeastern Pima County is Arizona’s longest effluent-dependent river and creates the County’s principal wetland habitat. Significant steps are underway to improve wetland ecosystems along the effluent-dependent Santa Cruz most notably Pima County’s Regional Optimization Master Plan (ROMP) and the Loop Recreational Trail. Using the successful EPA-funded “Living River” series implemented by the Sonoran Institute as a model, Pima County and the Pima County Regional Flood Control District developed a monitoring strategy and similar reporting tool for the Santa Cruz River in Northwest Tucson and Marana with the assistance of a Technical Committee of experts and stakeholders.
The Regional Optimization Master Plan (ROMP) upgraded the two major regional wastewater treatment plants discharging to the effluent-dependent Santa Cruz River, which began discharging improved water quality to the effluent-dependent Santa Cruz River in 2013. Pima County has been evaluating the effect of effluent water quality upgrades as a result of ROMP on a wetland health.
Living River Reports
Other project publications can be found in the tabs below. Resources and other reference materials can be found at the Lower Santa Cruz River Research Papers and Reports page.
A Living River - Charting Wetland Conditions of the Lower Santa Cruz River
Since the upgrades, A Living River annual reports have documented profound improvements in the wetland health along the effluent-dependent Santa Cruz including:
- Improved river water quality, including lower ammonia and biochemical oxygen demand with higher dissolved oxygen, improving conditions for aquatic life.
- Improved water clarity.
- Broadened diversity of macroinvertebrates, including increased presence of species sensitive to water pollution.
- Five fish species now thrive, whereas none lived in most river reaches before.
- Citizens observed more than 221 bird species; Sandhill Cranes sighted recently.
- Sustained recharge has risen to about 36,600 acre-feet per year, nearly double the pre-upgrade rate, despite an 8% reduction in volume of water released to the river.
- RWRD’s odor measuring technology shows little to no odors leaving the wastewater facilities’ property under normal operating conditions after WRF upgrades; prior to upgrades, odors were an ongoing complaint of nearby residents and river visitors.
- Increased linear park public use, mainly by pedestrians and bicyclists.
- More than four thousand people have attended public education and outreach activities featuring the Living River.
In short, Living River annual reports have documented public benefit of a substantial investment in improved infrastructure, turning the river corridor from a liability to community asset.
Watch a short video on the project.
Historical Conditions Report
The report on the Historical Conditions of the Effluent-Dependent Lower Santa Cruz River was completed in March 2013 to identify baseline and past history of the effluent-dependent reach. The report covers stream discharge and loss, channel morphology, vegetation, macroinvertebrates and water quality. It projects changes that the team thought might occur after treatment plant upgrades.
A
CEP was granted to the District which will help to preserve, protect and enhance riparian vegetation and aquatic habitat within the Santa Cruz River.
A summary of the project progress is now available. This project is in the Alternatives Development Stage. A stakeholder meeting is scheduled for May 21, 2020. In December 2019, the project team held three open houses along the river to discuss public interest and priorities for the Management Plan.
The approximate limits of the Santa Cruz River Management Plan (Grant to Trico) are shown on the project reach map. The lateral extent along this alignment is limited to locations where RFCD has operational control (ownership or maintenance responsibilities).
The lower portion of the Santa Cruz River in Pima County constitutes the County’s principal wetland habitat. Comprised of routine discharge from the Regional Wastewater Reclamation facilities thereby creating improved wetland ecosystems and floodplain aesthetics along the lower Santa Cruz River. This project, with the assistance of experts and stakeholders, will provide strategic planning and planning-level alternatives to help balance environmental, water resource, recreation, education, and flood hazard needs, desires, and concerns.
The Pima County Regional Flood Control District (District) is seeking professional consulting engineering (Consultant) services necessary for developing a Santa Cruz River Management Plan, which will identify flood hazard areas and drainage problems leading to cost-effective, multi-benefit solutions to alleviate or manage flooding in the study area.
The District will participate in community engagement throughout the project. Initial insights will be from a community engagement effort of priorities, values and concerns being conducted by the Sonoran Institute, which has collected over 500 responses from an on-line survey.
Public Meetings: Open houses for the public will occur in each of the subreaches at the following times during the project:
- At initiation of the project to inform the public and solicit input on problems and opportunities (December, 2019)
- To present and discuss possible alternatives (Spring, 2020)
- To present recommended alternatives (Spring, 2021)
Stakeholder Alternative Working Groups: Help develop an appropriate set of reach specific alternatives
Representation includes
- Community Groups
- Community Water Coalition of So. AZ
- Jurisdictions
- Landowners
- Public Safety
- Water Owners
Stakeholder Meetings: These will include representatives of all interested organizations to review the possible alternatives and implementation plan.
FEMA Floodplain Map Revision
The Flood Insurance Rate Map (FIRM) for a community depicts the Special Flood Hazard Area (SFHA) which is the area that has been determined to be subject to a 1-percent (100-year) chance of flooding in any given year. The previous Santa Cruz River Floodplain limits (Grant Rd. to Trico Rd.) shown on the FIRM were outdated.
The Pima County Regional Flood Control District has applied for a Letter of Map Revision (LOMR) from the Federal Emergency Management Agency (FEMA) to request a revision to FIRM panels 04019C0415L, 04019C0420L, 04019C1005L, 04019C1010L, 04019C1020L, 04019C1030L and 04019C1040L along the Santa Cruz River within Unincorporated Pima County and the Town of Marana, as part of the Santa Cruz River Management Plan, Grant Rd. to Trico Rd.
The LOMR request is expected to revise the following flood hazards along the Santa Cruz River:
- SFHA floodplain limits and base flood elevations will increase and decrease.
- The floodway for the Santa Cruz River will be revised from just downstream of the Sanders Road bridge to the Pima/Pinal County border.
Individual properties will be affected by these changes. Maps and a detailed analyses of the proposed flood hazard revisions can be viewed at the links below: