Solution: The streambank at a particulary vulnerable stretch of the gully will be reconstructed with a living cribwall to control erosion and restore stability to the bank. (The rest of the bank was also re-planted with riparian vegetation).
How a Cribwall Works: Since the materials used in a cribwall are organic, they can usually be found on-site (fallen trees, branch cuttings, etc). These materials are layered up the bank and covered with soil. The live cuttings will quickly take root and add rootmass to the streambank, preventing soil from eroding. The growth of plant matter results in a much more aesthetically pleasing solution than would concrete or rip-rap.
Step One: The bank is carved out by an earth-mover and a footer log (taken from woods near the site) is placed at the base of the foundation. Smaller logs are placed perpendicular to it, pushed into the bank, and secured by hand to build the first level of the wall.