Visit the CDC’s COVID-19 Integrated County View Map
This site includes an interactive map that shows various data points, including county test positivity and total new cases per 100K: https://covid.cdc.gov/covid-data-tracker/#county-view. Users should scroll over to see the full table, but moderate transmission starts with 5% and then goes up. So, when CDC says universal use of eye protection for resident care for facilities in communities with at least moderate-substantial transmission – that is essentially the same as having a facility in the >5% test positivity (or yellow and red counties).
More detail about how CDC defines “moderate” and “substantial” transmission can be found in the table on this webpage: https://www.cdc.gov/coronavirus/2019-ncov/hcp/framework-non-COVID-care.html.