I would be interested to learn why Denver Water finds it necessary to abruptly change the flow rates out of Gross Reservoir. Is it impossible to plan or make gradual changes that minimize the impact on the fish and invertebrates that reside in Boulder Creek?
Sloan, Joseph A.
To: Paul Prentiss
I sent your e-mail to staff in our Planning Section. I will send your e-mail and this response to the members of the Citizens Advisory Committee (CAC). The CAC meetings are open to the public and if you have any questions or comments you would like to send to the CAC please contact me and I will make sure they receive your comments.
From Planning -
The water commissioner may order Denver Water to adjust the amount of water we are releasing from Gross Reservoir “to the creek”. The phrase in quotation marks refers to the water we allow to flow past our diversion point for South Boulder Canal. The order may result from a change in the river “call”, i.e. there may be more or less water needed to satisfy downstream water rights, or it could be related to a change in the natural flow entering the reservoir.
Denver Water may need to change the amount of flow we are sending to Ralston Reservoir via the South Boulder Canal. Toward the end of October, we needed to shut off the South Boulder Canal in preparation for a construction project on the canal.
DW has outflow ramping requirements from Gross Reservoir which are part of our Federal Energy Regulatory Commission license. Except during emergencies, we follow these requirements. The Colorado Division of Wildlife and Trout Unlimited were involved in developing these requirements. The flow changes shown in Mr. Prentiss’ attachment adhered to the ramping requirements.
Again please contact me if you have any questions,
Joe Sloan, Staff Liasion to the CAC
Denver Water, Community Relations
1600 West 12th Ave.
Denver, CO 80204
(ph) 303-628-6320 (fax) 303-628-6349
To: "Sloan, Joseph A."
Bcc: Larry Quilling
Many thanks for your prompt and detailed response. I understand the need to adjust the flow and that construction projects may require such action. My question pertains to the transition rate.
Just so I understand.....on 10/22/08 at 8:30 AM the flow was at 80 cfs and over 5 hours it was cut to 11 cfs (86% reduction). No portion of this change could have been implemented over the course of the 10 previous days when it was consistantly running at 80 cfs. The fact that the change was within acceptable limits doesn't make it right. Perhaps I'm missing something or don't understand the process. What I do understand is observing stranded fish in side channels with a low probability of survival.