4.1. Reporting and analysis subwatershed units

The reporting and analysis units were based on geographical subregions of the Feather River Watershed, which in the Report Card are called subwatersheds. The Feather River Watershed, a subbasin of the Sacramento River Basin, consists of the watersheds of the Feather, Yuba, and Bear rivers. The logical reporting subregions were fairly predetermined by organizations and agencies working in this region. These areas are divided based on the upper and lower reaches of the river in relation to the major reservoirs on the river. For example, the reaches of the Lower Feather are designated below Lake Oroville, and the Lower Yuba below Englebright Dam. Deer Creek had its own reporting unit based on the availability of data for this Yuba River tributary, and how the subwatershed is influenced from a social and geographical point of view.

The USDA Natural Resource Conservation Science (NRCS) watershed boundary dataset, CalWater, was used to create the reporting regions. The Hydrological Area Boundaries (HAB) provided the boundaries for the East Branch North Fork Feather, Lower Feather, Lower Yuba, Middle Fork Feather, Middle Yuba, North Fork Feather, North Yuba, South Yuba, and Upper Bear. HAB name alone didn’t designate the regions, for example, South Honcut Creek, Sutter Bypass, and below Oroville Reservoir, were assigned to the Lower Feather subwatershed and Ute Mountain was assigned to the Lower Yuba. The other two boundaries, the Lower Bear and Deer Creek were constructed using the Hydrological Super Planning Watershed boundaries (HSPW). For Deer Creek, this included the designations HSPW Upper Deer Creek and Lake Wildwood, and for the Lower Bear, these included Upper Dry Creek, Clear Creek, and an undefined region associated with the Bear River. CalWater’s planning watershed at the mouth of the Lower Bear was assigned to the Lower Feather, so this region was clipped so that it could properly be assigned to the Lower Bear.

Analyses were conducted for planning watersheds (small creek drainages) within subwatersheds, or for the subwatersheds as a whole. All results were reported at the subwatershed scale (e.g., Lower Feather, South Yuba)