From email from Reclamation (Kara Lamb):
Now that fall has arrived, we have several maintenance projects going on across the Colorado-Big Thompson Project. To accommodate this work, most of the C-BT is basically shut down for the next few weeks.
On the C-BT West Slope, our operating partner for the Collection System, Northern Water, is working in the connecting channel between Shadow Mountain Reservoir and Grand Lake. You can learn more information on that project by visiting Northern’s “Latest News” section on their Website at LINK Diversion of West Slope water to the east portion of the C-BT is significantly slowed while this work is underway. The channel work is scheduled through October 30.
We are bringing a minimal amount of water through the Alva B. Adams Tunnel into the Estes Park area. Marys Lake is currently full and will remain high into next week. Similarly, Lake Estes is also near full. The water elevation there will remain around 7473–about two feet from full–through this weekend and into next week, as well. Marys and Estes could start going down sometime next week.
Releases from Olympus Dam on Lake Estes are currently bypassing native inflow–the amount of water normally in the Big Thompson River this time of year. We anticipate that the 35 cfs currently being released from the dam to the river will continue through October.
Pinewood Reservoir will be drawn to dead storage by this Sunday, October 3. The purpose of lowering the reservoir is to facilitate work inside the Bald Mountain Pressure Tunnel, the pipeline taking water from Pinewood to the Flatiron Penstocks. This work is scheduled through October and into mid- November. We anticipate we will start filling Pinewood Reservoir again in late November.
The water elevation at Carter Lake reservoir will continue to drop over the course of October. With Pinewood drawn down, deliveries to the water users on the Big Thompson River will be made from Carter Lake. This means, demands will be pulling water from Carter at both the Flatiron Plant and from Dam #1 for the rest of the month. Currently, Carter is at a water level elevation of 5703. That is approximately 56 feet down from full. While the South boat ramp is out of the water, the two boat ramps at the north end of the reservoir will likely not be impacted this year. The current rate of drop is about 3 inches a day, but that will vary day-by-day and is dependent on the weather. It is likely hotter weather will drive higher demands.
One of the most significant changes for fall operations is at Horsetooth Reservoir. Water levels at Horsetooth have been unusually high all year due to the snowpack, large run-off, and wet spring. Now that the C-BT project is down for one of its annual maintenance periods, no water is being delivered to Horsetooth. With the heat and the nearing of the water year’s end for the reservoir, water users are taking their water. As a result, approximately 760 cfs is currently being delivered out of Horsetooth. Today, the rate of drop was around 2/3 a foot, a day. But just like the draw from Carter, the rate of drop at Horsetooth will also fluctuate day-by-day throughout the month. As of this e-mail, the water elevation at Horsetooth is 5399, about 31 feet from full and about 12 feet above the 3-lane boat ramp in the South Bay. The majority of boat ramps at Horsetooth stay in the water until an elevation of 5385. Normally, we hit that elevation around Labor Day. This year, we might not see it until the second week of October. The water year at Horsetooth Reservoir ends on Halloween, October 31.
We typically complete our annual maintenance work and being bringing the C-BT system back up to full operating status in November. This includes beginning to refill Carter and Horsetooth reservoirs in late November and early December. We typically turn the pump on to Carter first, then start running water to Horsetooth. I will keep you all posted as best I can as we move through this season’s changes.
More Colorado-Big Thompson coverage here.