Drainage Design Manual - the City of San Luis Obispo

SECTION 11.0RIPARIAN REVEGETATION PLANNING AND IMPLEMENTATION11.1 GeneralStreambank repair and channel maintenance projects may require stream channelmodifications that include shaping, widening, deepening, straightening, and armoring.Many channel management projects also require building access roads for maintenancevehicles and other equipment. These construction activities can cause a variety ofimpacts to existing sensitive riparian and aquatic habitat that, depending on the selecteddesign alternative, range from slight disturbances to complete removal of desirablewoody vegetation and faunal communities. In urban areas within the SLO creekwatershed, riparian vegetation often provides the only remaining natural habitat availablefor wildlife populations. For this reason, the biological consequences of channelmaintenance projects must be seriously accounted, evaluated, and mitigated.Revegetation will often be required on streambank repair and other channel maintenanceprojects to mitigate impacts to natural areas as determined by applications of theCalifornia Environmental Quality Act (CEQA), Section 1600-1607 of the California Fishand Game Code (Lake/Streambed Alteration Agreements), and Section 404 of the CleanWater Act (permitting to fill wetlands). This section of the DDM is intended to provideguidance for revegetation of riparian areas that are modified, created and/or managed forflood damage reduction, stream enhancement, and bank repair.11.2 Design ApproachThe benefits of riparian areas to human communities are many. Riparian areas providesignificant ecological, flood control, water quality, agricultural, aesthetic, andrecreational functions. Revegetation design must always recognize the potential ofriparian areas to function as such and must attempt to accommodate and enhance thispotential within the context of opportunities and constraints for particular projects.11.2.1 Establishing Realistic Revegetation GoalsIt is important for a biologist or revegetation specialist to participate in the initialassessment of opportunities and constraints for a project to help planners and engineersestablish realistic revegetation goals. Maintenance supervisors and personnel responsiblefor the long-term management of a proposed project should also participate inrevegetation goal setting. Revegetation goals that are incompatible with projectopportunities and constraints will almost certainly fail.The revegetation specialist should promote flexibility in hydraulic design toaccommodate vegetation whenever possible. Channel designs that can assume highroughness values and allow for the largest possible rights-of-way usually provide thegreatest revegetation opportunities. Generally, the more space available for vegetationand channel conveyance, the more the design process can attempt to preserve andSLO Creek Drainage Design Manual 135 February 2003