Laserfiche WebLink
<br />OOJ8-:.8 <br /> <br />Cimarron Dredging Environmental Assessment <br /> <br />tubifex worm. Whirling disease has devastated the rainbow trout population in the Gorge and by <br />increasing sediment the problem may be increased. <br /> <br />Response: The proposed project is designed to eliminate or minimize the amount of sediment <br />transported as a result of the dredging project. The river will be monitored while dredging <br />activities are occuring, and stopped if suspended sediments start to deposit in the Gunnison River <br />below Crystal Reservoir. The great majority of sediment in the Gunnison Gorge is caused by <br />!lash !loods downstream from Crystal Reservoir and by tributaries upstream from Crystal. <br /> <br />. <br /> <br />Comment 3: The Report notes that Reclamation will visually monitor the water quality in Crystal <br />Reservoir and if the lower end becomes significantly turbid, dredging activities would be <br />stopped. Often. including the past few weeks when the Cimarron River was running high due to <br />heavy rains in the Cimarron drainage. the reservoir was clear but releases out of Crystal were <br />extremely turbid. The monitoring must be done in the river below Crystal Dam at the East <br />Portal. The report does not identify the agency that would make that decision. The Colorado <br />Division of Wildlife should be consulted for their evaluation. <br /> <br />Response: The Colorado Division of Wildlife was consulted and will continue to be consulted <br />during the dredging project to address concerns to fisheries resources. Monitoring will be <br />conducted at the East Portal below Crystal and is indicated as Crystal South Tailbay Site. Water <br />quality measurements will be taken at the 7 sites identified in the EA before and during the <br />dredging activity. The CDOW will be consulted and the visual monitoring of Crystal will be in <br />addition to the 7 sample sites. It is true that Crystal Reservoir does discharge cloudy water even <br />when reservoir surface water appears clear. <br /> <br />US Geological Survev <br /> <br />Comment I: It would be helpful to include in the EA a description of how releases are made <br />from Crystal. For example. the elevation of the release relative to the bottom of the reservoir. <br />This would be useful in determining how sediment may move through the reservoir. <br /> <br />Response: A description of how releases are made from Crystal Reservoir is included with <br />discussion of the Aspinall Unit under the Socioeconomic section. <br /> <br />Comment 2: There is no mention of the threshold at which dredging would cease. Which <br />parameters will be used to determine whether cessation of dredging would occur? As we <br />discussed, there are ways to determine if turbidity is associated with sediments or nutrients and <br />the associated plant growth. Using secci disc and measurement of chlorophyl-a and nutrients <br />(low level method) a determination could be made about what is effecting the trophic status of <br />the reservoir. Once that is established. you could use secci-disc measurements to monitor the <br />reservoir and determine the trophic status (once you establish the trophic status of the reservoir is <br />not sediment or nutrient limited then you could make the assumption that amy changes in <br /> <br />29 <br />