SFPUC 2001 Alameda Watershed Management Plan

XII. SUMMARY OF COMMMENTS AND RESPONSESB. SUMMARY OF COMMENTS AND RESPONSEScumulatively significant impacts that negatively affect riparian and aquatic wildlife. Nowhere inthe EIR are the negative aquatic and hydrologic impacts of grazing analyzed.” (Alameda CreekAlliance)Comment K-6: “Ecologist A. J. Belsky (1999) recently conducted a systematic literature reviewof peer-reviewed experimental studies on the effects of livestock grazing on stream and riparianecosystems in the west. Livestock grazing was found to negatively affect water quality andseasonal quantity, stream channel morphology, hydrology, riparian zone soils, instream andstreambank vegetation, and aquatic and riparian wildlife. These impacts obviously havesignificant cumulative negative effects for aquatic and riparian special-status species. No positiveenvironmental impacts were found. This study is included as Appendix 3. The followingassertions about grazing impacts are based on verifiable scientific data, have been published inpeer-reviewed technical and scientific journals, and are referenced in Appendix 3. The negativeinfluences of cattle grazing on riparian and aquatic ecosystems can be summarized as follows:• Water qualityCattle grazing increases nutrient concentrations and bacteria and protozoa. Sediment loadand turbidity are increased, as well as water temperature. Dissolved oxygen levels possiblydecline.• Stream channel morphologyChannel width increases, and water depth decreases with cattle grazing. Gravels in thechannel bed tend to be lost in the erosional environment and fine sediments increased in thedepositional environment. Streambank stability is reduced, streambank undercuts arereduced in quality and quantity, and pools decrease in number and quality.• Hydrology (stream flow patterns)With cattle grazing, overland flow from runoff increases, and peak flow and flood watervelocity also increase. Summer and late-season flows decrease, and the water table islowered.• Riparian zone soilsGrazing increases erosion, the amount of bare ground, and soil compaction. Infiltration ofwater decreases. Litter layer decreases and soil fertility declines.• Instream vegetationAlgae growth increases with grazing, but higher plants (submerged and emergent) oftendecline in abundance.• Streambank vegetationHerbaceous cover, biomass, productivity, and native plant diversity decline due to grazing.Overhanging vegetation and tree and shrub biomass and cover decline. Plant speciescomposition is altered and plant structure (horizontal and vertical) is simplified. Plant agestructure becomes even-aged and plant succession is impeded.NOP 96.223E: Alameda Watershed Management Plan C&R.91 ESA / 930385