Fish diversity is tightly connected to the quality of aquatic habitats in any river or stream. To assess whether aquatic habitats are supporting desirable fish communities, we compared the species present in an area to the species that the Arizona Game and Fish Department has identified as desirable or undesirable.
How is it scored?
The Verde Watershed Fisheries Management Plan developed by the Arizona Game and Fish Department includes 82 management units. For each unit, Arizona Game and Fish maintains a list of desirable and undesirable species. Species present that are not on either of these lists (i.e., are deemed neither desirable nor undesirable) are also included. Indicator grades were calculated as the difference between the fraction of desirable species present and the fraction of all species present that were undesirable.
For the 2025 Report Card update, the Fish indicator was changed to Native Fish indicator. The updated methodology focuses on the presence of native fish surveyed in each region.
The Verde River Watershed was home to 11 different native fish species that were common in the Verde River and its tributaries as recently as the 20th century. Due to anthropogenic threats, including but not limited to the introduction of invasive species, habitat degradation, pollution, and low flows due to overuse of groundwater and surface water, several native fish species have since struggled to persist. Scores are based on the percent of historical native fish species that were found during surveys within each region. It should be noted that the number and extent of surveys varied across regions, which can also affect the number of native species found in each region and the resulting scores.