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DOLORES RIVER GRAVEL PIT IMPACT <br />July 18, 2001 <br />To CFAR Committee <br />INTRODUCTION <br />I was asked by Pat Kantor to provide a summary of the hydrologic impacts that might <br />occur from the impact of gravel pit mining in the Dolores River valley above the town of <br />Dolores. I have not limited myself to the hydrology because this is a systems problem not <br />just a simple cause and effect. <br />I am interested in the Dolores River System including its geologic history and current <br />state. Presently my concern is with the human impact upon the river that could lead to the <br />general degradation and value of the river and to the increased potential of flood hazazd <br />to downstream residents. <br />The floodplain azeas of the Dolores River aze subject to periodic inundation that may <br />result in loss of life and property, health and safety hazazds, disruption of commerce and <br />governmental services, extraordinary public expenditures. for flood protection and relief, <br />and impairment of the tax base, al] of which adversely affects the public health, safety, <br />and general welfare. There have been eight flood events greater than 6,000 cfs and three <br />greater than 8,000 cfs in the past 90 years. <br />QUESTIONS NOT ADEQUATELY ANSWERED <br />`' 1. ~ What aiaza the accumulative impacts of multiple gravel pit mining activities and <br />pits on the floodplain of the Dolores River? <br />2. Do these activities and their modifications to the landscape increase the damage <br />incurred by natural. flooding? <br />3. What other negative impacts do these activities have upon the general welfaze of <br />the community and users? <br />4. What aze the limits of modification of the channel that can be tolerated by the <br />river system without severely increasing flood hazazd? <br />These and other questions can only be tackled from a systematic study of the Dolores <br />River Drainage watershed. I believe that a systems approach to the watershed is the best <br />strategy because it does not just limit itself to the impact of gravel mining but to the <br />impact of all human and natural processes. <br />GRAVEL NIINING <br />Gravel is an important resource for our industrialized culture. In the U.S. 11 tons per <br />person of stone and aggregate aze consumed each year for roads, buildings and other <br />construction projects. Thus, good gravel sources are modern day "gold mines." Gravel <br />