BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

some designated boundary or sphere of influence around an activity, remainrestricted to within that boundary. 938.14.3 BIOLOGICAL MONITORINGFreshwater lake nearshore and estuarine biological systems are considereddiverse and complex. Shorezone protection projects may benefit one or morecomponents of the biological system while adversely impacting others.Biological assessments of shorezone protection projects are used to predictecosystem adjustment as well as the importance, spatial extent, and severity ofthe expected biological alterations. In practice, analysis usually focuses uponspecies of commercial or recreational importance; rare, threatened, orendangered species; and sensitive or highly productive habitats. 94Habitat-based evaluation procedures are designed to document the quality andquantity of habitat available for aquatic and terrestrial animals. Theseprocedures can be used to compare the relative value of different areas at thesame time (baseline studies) and/or the relative value of one area at differentpoints in time (impact assessment) as compared to a proposed future scenario.8.14.3.1 BIOLOGICAL DESIGN CONSIDERATIONSThe construction of shore protective structures usually produces short-termphysical and water quality disturbances. These perturbations directly impactbiological communities and may result in long-term impacts. For example,some ecosystems damaged by construction or water quality degradation mayrecover slowly and take years to achieve preconstruction levels. Many of theseimpacts are very difficult to avoid. However, construction activities can oftenbe timed to avoid critical events such as fish spawning or migratory shorebirdnesting. Sometimes protective structures can be located to avoid sensitivebiological areas.Shorezone structures alter bottom habitats by physical eradication and in somecases by deposition or scour. However, certain hard structures may create ahighly productive, artificial reef type habitat. The type of material used tobuild a structure and the surface area of the structure will influence the qualityof the newly created habitat. Some protective structures, which are connectedto the shore and extend some distance lakeward, may potentially interfere withthe migration of certain fish species. To alleviate these concerns the structuremay be modified to include gaps or shortened in length, or located outside thepath of the migratory movement. 9593USACE, 1989, EM 1110-2 -5025, Environmental Engineering for Coastal Shore Protection94USACE, 1989, EM 1110-2 -5025, Environmental Engineering for Coastal Shore Protection95USACE, 1989, EM 1110-2 -5025, Environmental Engineering for Coastal Shore ProtectionTRPA BMP HandbookCHAPTER 8: Shorezone Protective Structures and BMPs2012 Page 8-91