WGFCI Comments: Alternative Options Report

Page 1

August 21, 12

Comments on the Chehalis Flood Mitigation Alternatives Report 1. On page 3 is the statement that a dam would lower flood elevations by “ almost 2 feet at Montesano.� This statement is unclear as different modeling assumptions produce different estimates of the flood elevations throughout the basin. In reviewing Appendix F, we could find only one instance where the flood elevation would be reduced by this amount. This is in Table 8 in which a comparison is made between a 100year flood and the 2007 flood. Given the challenges of understanding the 2007 flood, i.e. gages disappearing and the impact of down timber, we suggest that this estimate may well have a large error factor. We suggest that this statement needs to be highly qualified. 2. On page 3, reference is made to the Anchor QEA fish study. This study is problematic. There is barely a year’s worth of data. Based on conversations with fish biologists our conclusion that this amount of data is not nearly sufficient. It does not take into account different water quality, water quantity, different return rates for salmon and other anadromous species over several years, nor does it include the wide range of salmon and other species that are in the Chehalis. The juvenile fish assessment project in Grays Harbor demonstrates the need for several years worth of data. This study, done by the Wild Fish Conservancy, is beginning its third year. When asked how many years worth of data were essential to reaching reasonable conclusions, the answer was a minimum of three years with the possibility that a fourth or even a fifth year was necessary. 3. During the workshop, three options were presented to the Flood Authority. It is not clear where these came from and we have heard Flood Authority members make the same comment.


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