Colorado-Big Thompson Project update: Winter refill for Carter Lake should start up in December

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From email from Reclamation (Kara Lamb) that was buried in my inbox since last Friday:

As we move into the weekend, we have several operational changes taking place across the Colorado-Big Thompson Project on the east slope.

Visitors to and residents of Estes Park will likely notice that Marys Lake and Lake Estes are gradually going down in water elevation. By the end of next week, Marys Lake will be dropped down for maintenance and inspections. It is anticipated that its water level will begin to rise again by mid-to-late December.

At Lake Estes, the drop in water level is to accommodate some annual maintenance and inspection at Olympus Dam. The reservoir is expected to drop about 12 vertical feet by Monday morning, November 21. It will begin to rise again by late Monday afternoon.

As the water level at Lake Estes drops, the release from Olympus Dam to the Big Thompson River through the canyon will also slowly decline. Today, it dropped approximately 30 cfs from 300 to about 270 cfs. Releases will continue to drop through the weekend and into the top of next week. By Monday night, November 21, releases to the Big Thompson River should be back to normal flows for this time of year, which are approximately 25 cfs.

Diversion from Olympus Dam to the southern power arm of the C-BT is currently off-line while other project maintenance is underway. The contractor continues to work on the replacement of the open-faced Pole Hill Canal, installing closed box culverts. This work is split into two phases, the first of which is being completed this fall and is scheduled to wrap up in mid-December. Attached you will find a photo of the work currently underway along the Pole Hill Canal.

With Pole Hill off-line, no water has been flowing into Pinewood Reservoir, which has maintained a high water elevation through October and well into November. This will change starting Monday, November 21. On Monday, we will begin to draw Pinewood’s water elevation down to accommodate a maintenance project on the Bald Mountain Pressure Tunnel, which carries water from the reservoir to the Flatiron Penstocks. Residents of and visitors to Pinewood will see the water elevation decline through the week, hitting a low of about 6550 by the the following Monday, November 28. It will remain at the low level well into December, until the work on the Pressure Tunnel is complete. We have been in close contact with the Newell-Warnock Water Association at Pinewood so they are aware of these changes to the maintenance schedule.

We are anticipating that the southern power arm of the C-BT will start to “water up” by mid-to-late December.

Meanwhile, water elevations at Horsetooth are still climbing slightly, but will level off as these changes across the project go into effect.

Water levels at Carter Lake are likely to continue dropping, as is typical for this time of year. We anticipate the start of refill for Carter to begin in mid-to-late December, as normal.

From email from Reclamation (Kara Lamb, November 16):

In order to accommodate on-going maintenance at the Shoshone plant, we will reduce our releases from Green Mountain Dam to the Lower Blue River from 300 to 200 cfs. The reduction will be made in two steps of 50 cfs each. This afternoon, we dropped releases to around 250 cfs. Tomorrow morning around 8 a.m. we’ll drop releases to about 200 cfs. We will keep 200 cfs in the Lower Blue through Thanksgiving.

More Colorado-Big Thompson Project coverage here.

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