Puntledge River: Higher river flows Thursday to Monday
April 6, 2017
From BC Hydro
"The latest weather forecast has worsened with more rain. The forecast calls for about 80 mm of rain in the upper watershed through tomorrow. Although we increased the water release from the Comox dam last night, it will not be enough to control the Comox Lake reservoir. As a result, we will need to increase the flow from the dam down the Puntledge River from 45 m3/s to about 80 m3/s tonight. The higher river flow rate will likely last through Monday.
We may increase the flows higher than 80 m3/s over the next few days should the inflows be even more than forecast. At this stage, a spill of 80 m3/s will keep the reservoir below 134.5 m.
We are now extending the public safety notice for people to stay away from the Puntledge River throughout the river system.
There is no downstream flood risk.
Experienced kayakers with the Vancouver Island Whitewater Paddling Society will be able to take advantage of these water abundance conditions. There will be good kayak flows."
April 5, 2017
From BC Hydro
"Today we will be concluding another two-day fish migration flow within the Puntledge River. Then beginning tonight, we will increase the Puntledge River flow from the current discharge of about 12 m3/s from Comox dam to about 45 m3/s. This flow rate will be in place until Monday when the generating station comes back online from the maintenance shutdown.
Puntledge River flows will be within seasonal levels starting tomorrow but the area of the river from the diversion dam to the generating station will see higher than normal flows. This area includes Barber’s, Nymph and Stotan falls. For public safety please stay away from this 5-6 km section of river.
The Comox Lake reservoir moved down to about 134.15 metres from last week’s water release, but with the recent storm, has increased to 134.3 metres and slowly rising. The water release through the rest of this week will help control the reservoir level."
March 29, 2017
From BC Hydro:
"The recent rains, and with the Puntledge River generating station being out of service for maintenance, have increased the water level in the Comox Lake reservoir. To control the reservoir level, we will increase the water discharge down the river beginning tonight. For public safety, we ask the public to stay away from the Puntledge River from Wednesday night through Monday.
We are currently in the middle of a maintenance overhaul to our Puntledge River generating station. The work began on March 20 and is planned for completion on April 10. All water flows are therefore bypassing the penstock and generating station. We are providing minimum fish habitat flows through the river system, and today, are concluding a two-day fish migration flow of about 12 m3/s for areas like Stotan Falls. Water releases from the dam have ranged from about 12 m3/s to about 19.5 m3/s. However, water inflows into the reservoir have been around 50 m3/s to 60 m3/s. The reservoir level has increased and is now at 134.45 metres and rising. Water begins to free-spill over the dam at 135.33 metres. For this time of year, BC Hydro likes the reservoir at around 134 metres.
Beginning at 9 pm tonight, the release from the Comox dam will slowly ramp up to 65 m3/s by early Thursday morning. This flow rate will likely be maintained through Monday.
Another fish migration flow is timed for Tuesday and Wednesday.
This will be a good opportunity for experience kayakers to take advantage of the water abundance. With the Browns River currently flowing at about 20 m3/s, the 85 m3/s total flow rate is deal for kayaking conditions below the Puntledge/Browns confluence. Kayakers who enter the river should be members or in coordination with the Vancouver Island Whitewater Paddling society."
Previously: March 22, 2017
From BC Hydro:
"BC Hydro is currently in the early stages of a maintenance overhaul to our Puntledge River Generating Station. The work began on March 20 and is planned for completion on April 7. We do this about three times per year to maintain the facilities, much like people do with their cars, to keep the system safe and reliable. This includes closing off the penstock and de-watering it so we can undertake inspections, and to also clean the fish screen inside the penstock that is intended to screen out the out-migrating salmon that may enter the penstock back into the Puntledge River. The screen is intended to keep the fish from passing through the turbine. We also try to time the shutdown during the time of the year when there are the highest numbers of out-migrating salmon so they pass downstream and not potentially enter the penstock in the first place.
With the current powerhouse planned outage the penstock was de-watered on March 20 and is scheduled to come back on Friday, March 24. During this time Fisheries and Oceans Canada, for their fish hatchery, and the Comox Valley Regional District (CVRD), with their domestic water supply, transfer their water withdrawals from the BC Hydro penstock to the Punltedge River located beside the generating station. When the penstock is watered up they can then go back to withdrawing water from it. The powerhouse remains out of service; we just keep the penstock full of water.
The issue is the modest rains yesterday resulted in the Browns River, which enters the Puntledge River just upstream of the generating station, seeing an increase in sediment or turbidity. As a result, the CVRD stopped withdrawing water from the river early this morning and were drawing from their approximate six reservoirs around the Comox Valley, which have limited storage. Turbidity levels above 1 NTU can result in the CVRD issuing a community boil water advisory. The CVRD is now back to slowly pumping water from the river, as the turbidity level has come down a bit, but that threshold is tenuous should the rain hit again.
We were alerted of the situation by the CVRD this morning and have been considering options through the day.
We are unable to stop the required maintenance work but are working hard to hopefully have the penstock watered up by end of day Thursday, a day ahead of schedule. The water source for the penstock comes from the Comox dam and that water source is cleaner. This will suitably deal with this issue but the potential turbidity coming from the Browns River, and the limited CVRD water storage within their own reservoir system, presents a water quality risk until then. So BC Hydro has also decided, in trying to assist the CVRD, is to dilute the water coming from the Browns River by releasing more cleaner water from the Comox dam and the Comox Lake reservoir. The extra water down the Puntledge River may also push some of the Browns River water more to the left bank of the river and help the water CVRD’s water intakes, which are located on the right bank of the river.
After the completion of a planned and regulated 48-hour fish migration pulse flow that ends at 9 pm tonight, BC Hydro will increase the discharge from Comox dam from 12 m3/s to 45 m3/s – a nearly four-fold increase. The higher river flow rate will likely last through Thursday until our penstock is full of water again.
For public safety, we ask the public to stay away from the Puntledge River from the Puntledge diversion dam to the powerhouse, which includes Barber’s Hole, Nymph falls and Stotan Falls, from Wednesday evening through Thursday evening while the high flow is in place."