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1\. '1\ II II :If Il ~II II I I I I I I I II II III II " , 6. Of most concern is the construction of the 300 ft berm by Four States Aggregates that is designed to have heights of several feet to possibly six feet or more. When there are volumes of water in excess of6,OOO cfs, the river channel will be artificially confined just north of the Akin property.' This unpedes the natural tendency for the river floodw~ters to spread out and dissipfite. 7. The. Four States Aggregates recognizes this problem. To quote from page,s 27D and 27E: "The construction of vegetated stockpile berms along the pit side closest to the Ijver will also further reduce the ability of the river to change its current channel, which at this point is relatively straight and along the east side of the valley. BeCause of the current channel configuration, there is a greater chance of stream course changes further downstream (such as on the Robinson and Akin properties and beyond) regardless of the Line Camp Pit presence." 8. By confinin'g the channel and preventing floodwaters from spread out in the normal floodplain, greater erosion Qfthe streambed occurs which in this case is just north of the Akin property.. These eroded stream gravels will be dumped in an area where the channel natuIally spreads out. That would be in the braided section on the Akin and Robinson property.. Thus, there is greater flooding and lateral migration of the braided stream channels. Where these new channels would occur is unpredictable, but almost assuredly they would negatively impact the Akin and ,Robinson property. . Conclusion The proposed berm design of the Line ,Camp gravel pit increases the risk of flooding from a high discharge event on the land of Jack Akin 'and Carol Stepe. This type flood event could threaten human lives and buildings on this property. , , Additional ,Comments Obstructing the natural course or channel of waters in the U.S. is contrary to the provisions offederaIlaw (33 U.S.C. Sec. 403). The south bermtbat Four States Aggregates plans to build spans 50 to 60 percent of the width of the Dolores River Valley. During a major discharge eve]~.t that breaches the gravel pits through pit capture, this south berm woUld impede water flow~, The two gaps in the south berm that are designed to drain backup waters in such an event could easily be overwhelmed. Because the berms are composed of soil and gravel fines, the berm could easily be eroded and increase suspended sediment load. This load would ultimately be discharged and deposited in the McPhee Reservoir. In addition, the water flow through the gaps would Affidavit of Dr. Robert W. Blair, Ph.D. Page - 3