This Watershed Improvement Plan (WIP) is for the Upper Granite Creek Watershed,
located in central Arizona in the Verde River Watershed . The goal of the WIP is to identify and prioritize watershed improvement projects critical to restore water quality. This project originated as a community-driven watershed survey and planning effort to address nutrient and bacteria water quality concerns in the watershed, funded by the Arizona Department of Environmental Quality (ADEQ) Targeted Watershed Improvement Plan Grant Program. The Granite Creek Watershed Improvement Council (WIC), a collaborative body with representatives from the City of Prescott, Yavapai County, Prescott National Forest, Arizona Department of Transportation, community members, and volunteers, participates in the planning.
The purpose of the WIP Program is to address specific pollutants that are causing impairment within targeted Arizona watersheds, identify potential solutions, and to develop an implementation plan that will reduce pollutant loads from nonpoint sources that cause surface waters to be listed as “impaired” or “not attaining” surface water quality standards. The goal of the ADEQ Targeted Watershed Improvement Grant Program is to use developed WIPs to focus on future on-the-ground priority projects that will ultimately lead to bringing impaired waters back into attainment of surface water quality standards.
Through data collection activities and local knowledge of the watershed, potential sources of pollution were identified as: aging and degraded municipal sewer infrastructure; failing or ill-maintained septic systems; water reuse; horses, cattle, and other livestock; and pets. Background sources such as wildlife and forest fires also contribute to nutrient loading. The lower subwatershed areas are highly urbanized. Therefore, the types of potential bacteria and nutrient sources are greater than in the mostly undeveloped upper subwatersheds. The urbanized creek segments have been channelized and separated from their natural floodplains, increasing the risk of flooding to nearby properties. The majority of natural riparian vegetation has been replaced by walls or other structures and cannot adequately perform biological filtration functions. Stormwater drainage from roads and neighborhoods is directed into the nearest waterway untreated. The data indicates that the primary factors leading to water quality impairments in the project area are nonpoint source pollutants, increased runoff volumes due to impervious surfaces, and a lack of stormwater detention and infiltration/filtration.
Green infrastructure (GI) is the primary recommendation for addressing stormwater and associated pollutants in the watershed. GI is a broad term for features that rely on natural processes such as soil, water, and plants to provide ecosystem services such as clean air, clean water, and temperature regulation. The WIC recommends that GI be integrated with traditional grey infrastructure to effectively reduce stormwater quantity before it enters the already overburdened sewer system and discharges to the nearest water body.
Because a watershed-aware citizenry is key to improving surface water quality, the WIC also recommends a variety of education and outreach activities to engage the community and raise awareness to targeting different audiences and community groups. Public workshops, mailings, educational articles, and expanding the existing creek signage and storm drain marker programs are recommended.
As part of a comprehensive strategy, the WIP also includes BMP recommendations for golf course turf management, manure management, green waste, forest protection and restoration, and invasive vegetation management. Specifically, the WIP identifies four priority BMP projects which include:
- Bioretention and Sediment Basins at Prescott Rodeo Grounds
- Whipple Street Bioretention Basins
- Green Infrastructure Demonstration at Prescott Community/Adult Center
- Green Industrial Site Practices at the APS Construction Yard
To ensure continued investments in watershed health, the WIC recommends that continuous, local funding sources be investigated.
You can download the full Granite Creek Watershed Improvement Plan 2.0 below. Please note file size.
Granite Creek Watershed Improvement Plan 2.0 (5.2 MB Download)