Waterfall in basalt canyon of the Rio de Flag, Picture Canyon Natural and Cultural Preserve, Photo Credit: Friends of the Rio de Flag
The Rio de Flag is the primary watercourse winding through Flagstaff, Arizona. The stream channel is ephemeral or intermittent depending on the season or local geology. The project area is located at an elevation of about 6,700 feet and passes through the City of Flagstaff and Arizona State Trust Lands, Section 4, T.21N, R.8E, along the Rio de Flag drainage of the Little Colorado River Watershed.
The area lies just below the City of Flagstaff’s Wildcat Hills Wastewater Treatment Plant (WHWTP). Tertiary treated sewage effluent flows through the project site in a northerly and northeasterly direction.
The stream runs through a narrow basalt canyon and supports an existing wetland plant community watered by upstream effluent discharges. Sometime in the past, the stream channel below the canyon was channelized, removing a number of natural meanders. The channelized section has no access to an adjacent floodplain and supports a very limited riparian plant community. (See Image).
Existing vegetation is primarily patches of bulrush (Scirpus spp.) in the channel proper. Noxious weeds such as yellow starthistle (Centaurea solstitialis L.) and Scotch thistle (Onopordum acanthium) have invaded the site due to the soil disturbance from the trenching activities. The result is a significant narrowing of the riparian area and a rapid transit of the perennial stream flow. There is a decrease in the volume and extent of soil moisture throughout the project area that has caused a decline or elimination of wetland areas.
The approximate length of the channel through the project site is one mile. About 0.75 mile of the channel has the potential for restoration work and enhancement. The stream corridor ranges from 50 to 100 feet in width and is largely bounded by rocky canyon escarpments.
Restoration activities focused on reconnecting the historic meanders and restoring natural stable channel and wetland features and functions. The potential riparian and wetland area will nearly double in size from two to five acres.