a. Hydroriparian includes any drainage with perennial surface water regardless of plant species composition; Mesoriparian includes any drainage without perennial surface water but any of the following species: Arizona Walnut (Juglans major), Fremont cottonwood (Populus fremontii), Gooding willow (Salix gooddingii), Arizona sycamore (Platanus wrightii), Arizona ash (Fraxinus velutina), netleaf hackberry (Celtis reticulata), or seep willow (Baccharis salicifolia); Xeroriparian includes any drainage with intermittent/ephemeral flow but not containing the above indicator species; Xeroriparian areas will have a representative vegetation volume of 0.500 m3/m2 or greater.

b. The lateral riparian boundary is a contiguous line along the canopy margins of the predominant overstory vegetation species parallel to a riparian area, where the lateral distance between canopy margins of individuals of the predominant plant species is less than two times the height of the tallest individuals. Where the distance between canopy margins parallel to the channel are greater than two times the height of the tallest individuals, the boundary is considered to be the top of bank of the channel.

c. Boundary between Meso and Xeroriparian habitat types -- any gap between Mesoriparian indicator species of 1,000 ft or greater will indicate a transition to xeroriparian. Mesoriparian boundary will be at indicator species’ canopy.

d. In braided riparian systems where ‘islands’ may occur, these are included as part of the riparian area. Islands more than 200 feet wide, or whose surface elevation is significantly higher than surrounding channels, are not included.

e. Because of natural variability, not all areas within mapped riparian areas will support the overall representative vegetation volume. Additionally, mapped riparian areas may include areas without representative vegetation volume, but do contribute to regional riparian system functions (e.g. drainage connectivity, sediment and nutrient transport, channel meander, etc.).

f. Riparian areas disconnected hydrologically from downstream riparian areas by human disturbance or impacts are not included.

g. The criteria for determining an upstream starting point (headwaters) of Riparian Areas with representative vegetation volume is where a discernible channel with an ordinary high water mark begins.

h. Vegetation volume within a riparian area will be determined using Pima County Regional Flood Control District Technical Procedure 116: Quantitative Methods for Regulated Riparian Habitat Boundary Modifications and On-Site Vegetation Surveys.