Granite Creek Watershed
Area Description
The Granite Creek Watershed is roughly 50 square miles in size and includes two lakes and nine named creeks totaling approximately 60 linear miles. The boundary of the watershed is formed by the Sierra Prieta and Bradshaw mountain ranges. The area of interest for the Watershed Improvement Planning project is the upper portion of the watershed, defined as Granite Creek and its main tributaries south of Watson Lake.
Land use and ownership in the watershed is diverse; the creeks’ headwaters reside in the Prescott National Forest, run through the grasslands of unincorporated Yavapai County, and then through urban areas of the City of Prescott. In 2008 Prescott’s population was estimated at 43,280 residents.
Impaired Waters
In 2004, Arizona’s 303(d) List of Impaired Waters (waters not attaining their water quality standards) listed two water bodies in the upper Granite Creek Watershed: Watson Lake and Granite Creek.
150-acre Watson Lake was listed as impaired for low dissolved oxygen, high pH, and high nutrient (nitrogen and phosphorus) levels. A 13.4-mile segment of Granite Creek was listed as impaired for low dissolved oxygen.
Although neither water body is presently impaired for E. coli, testing of bacteria levels in both bodies have consistently exceeded state water quality standards.