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<br />. <br /> <br />. <br /> <br />Groundwater RecharQe: Atthough Muddy Creek provides some groundwater recharge, there is a net <br />Joss of groundwater in the Muddy Creek basin due to consumptive use by hydrophytes and widening <br />and incisement of the stream channel, which has caused a reduction in hydraulic head in wetlands <br />adjacent to the stream. The reservoir will greatly increase the hydraulic head and provide a large <br />source of water that will effectively cause groundwater mounding in the reservoir's vicinity. The <br />groundwater mounding essentially represents an increase in groundwater recharge. Therefore, the <br />reservoir will not only replace the recharge functional value, but will greatly enhance the existing rate <br />of groundwater recharge. <br /> <br />. <br /> <br />. <br /> <br />Flood Stor8Qe and Oesvnchronlzatlon: The wetlands that will be impacted occur on the Muddy Creek <br />valley flat. On the average, streams ovenop their banks and inundate their floodplain one or more <br />times in '.5 years. When a stream overtops its banks, the vegetation on the floodplain slows the <br />velocity of water flow and detains a portion of the flood flow. These processes effectively slow flood <br />flow and desynchronize the flow to minimize damage to downstream areas due to an otherwise 'flashy' <br />flow regime. The effectiveness of the wetland depends on the density of cover and the horizontal and <br />vertical structure of the cover. As indicated, the wetlands associated with Muddy Creek have been <br />overgrazed to the point where flood storage and desynchronization values are relatively low. Further, <br />Muddy Creek does not overtop its banks as often as a stream in a more pristine condition due to <br />widening and incisement which additionally reduces functional value of the wetlands. Reservoirs have <br />been extensively used for flood control and their value in flood storage and desynchronization is high. <br />Therefore, the Muddy Creek Reservoir will more than fully replace this functional value of the wetlands <br />lost with construction of the Muddy Creek project. <br /> <br />. <br /> <br />. <br /> <br />Shoreline AnchorlnQ and Dissipation of Erosive Forces: The widening and incisement of Muddy <br />Creek has left a substantial portion of its banks bare. Most of the vegetation that lined the creek has <br />either been left above the stream, out of effective influence in terms of bank protection, or has <br />sloughed into the creek due to bank erosion. Therefore, the existing wetlands are not of high value in <br />regard to shoreline anchoring and dissipation of erosive forces. The reservoir will inundate and replace <br />a deeply incised segment of Muddy Creek. Because reservoirs have low erosive energy, the Muddy <br />Creek Reservoir will more than substitute for the reduced value of the inundated wetlands. <br /> <br />. <br /> <br />Sediment TrapplnQ: The ability of a wetland to trap sediment is directly related to its ability to store <br />and desynchronize flood waters. Therefors, the discussion presented above for flood storage and <br />desynchronization applies to sediment trapping. Since the Muddy Creek wetlands are generally in very <br />poor condition, their sediment trapping effectiveness is low. This especially applies to trapping of <br />sediments due to over1and flow and flooding of the valley flat area. Wetlands with low vegetative cover <br />and density, such as in the Muddy Creek basin, make poor sediment filters. Reservoirs are well known <br />for their ability to trap sediments. Reservoir design life is based on the calculated time frame within <br />which a reservoir is likely to be rendered ineffective due to sediment deposition and reduced water <br />storage capacity. Consequently, the reservoir's ability to trap sediment will greatly exceed the existing <br />wetland's ability by several orders of magnitude. <br /> <br />t <br /> <br />, <br /> <br />Nutrient Retention and Removal: A large portion of nutrient inflow into a wetland occurs as chemical <br />species attached to sediment particles which are trapped by the wetland vegetation as described <br />above. Currently, the degraded condition of the Muddy Creek wetlands have greatly reduce this <br />functional value. These sediment particles would sink in and be retained by the reservoir. Dissolved <br />nutrients are retained by wetlands through uptake by vegetation. Since the Muddy Creek wetlands <br />vegetation is in poor condition, the actual magnitude of dissolved nutrient uptake is greatly reduced <br />as compared to a wetland in good condition. The greater density of dissolved nutrients will cause the <br />solution to sink to the bottom of the reservoir into the conservation pool. Thus, a large portion of the <br />nutrient inflow is trapped in the conservation pool. Reservoirs act as thermal regulators and nutrient <br /> <br />, <br /> <br />6 <br /> <br />, <br />