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<br />.. <br /> <br />00101~ <br /> <br />. <br /> <br />. <br /> <br />be all wetlands within 1,000 feet of the channel and which were located to the <br />'south-'southwest of the channel. Direction of flow is important since overland <br />flows in Stages 3-5 generally come from the north-northeast direction. The <br />wetlands adversely affected by conveyance channel construction Were determined <br />to be 4,946 acres. <br /> <br />The road construction adjacent to the wetlands was estimated to affect about <br />80 acres, based on a 20-foot road width. Only direct displacement of .etland <br />acreage was considered here. <br /> <br />The total acreage of wetlands adversely affected by conveyance channel and road <br />construction is therefore 5,026 acres. Approximately 25 acres of the 5,026 <br />acres of wetlands affected by conveyance channel construction occur on the <br />Blanca liliA. <br /> <br />The acreage of wetlands in the project area that could be potentially impacted <br />by project pumping was also determined. These wetlands were determined using <br />the 1978-1980 water table maps as having ground "ater within 2-1/2 feet of the <br />ground surface. Hetlands with ground water within 2-1/2 feet of the ground <br />surface but outside of the projected USGS drm,down areas were deleted. Hetlands <br />impacted by the construction of the conveyance channel were not included again <br />under wetlands affected by project pumping impacts. A final delineation was <br />made to include only the percentage of wetlands that was shown to have high <br />infiltration rates (0.25 foot/day) from BR infiltration tests in the project <br /> <br />area. <br /> <br />Using the above criteria, it was determined that 3,434 acres of wetlands would <br />be adversely impacted by water drm,downs. Approximately 173 acres of the 3,434 <br />acres of drawdown affected wetlands occur on Blanca l~lA, while about 670 acres <br />of wetlands in the San Luis/Head Lake area are affected. <br /> <br />Thus, total wetlands adversely impacted by the project would be 8,460 acres. <br /> <br />In addition to the quantifiable impacts to wetlands identified above, a whole <br />series of indirect impacts could be expected, mainly as a result of decreased <br />plant vigor when ground water tables are drawn down. The following items <br />illustrate this thought: <br /> <br />(a) Increased wind erosion of soils, which could lead to more sediment <br />deposition in wetland depressions; <br /> <br />(b) Reduced biomass in the wetlands as vegetation species lose their vigor <br />and experience decreased density; <br /> <br />(c) Reduced retention time of overland (surface) runoff coming into <br />existing wetlands. As the project area in the vic~nity of these wetlands becomes <br />"drier" due to drawdown pumping, more of the surface runoff will tend to <br />infiltrate into the ground quicker. Retention of surface runoff in the existing <br /> <br />9 <br /> <br />~,~,~~%':~3:!t~~~~t~~~ :~..:~)~?~~. '~,.,_':;.:_ '... '.,~ , l~:~"~~.,~:,~~;"~~\~~~~lf';"!~~'V~~{('~~~'f.~r:r~~~~'::"~~~~~:~~~ <br />