At February’s Cowichan Watershed Board meeting, a motion was passed asking the Cowichan Valley Regional District to finance the annual operating cost of approximately $5,000 for an Automatic Snow Pillow Station on Heather Mountain. This request went to the CVRD board and has been approved for the 2012 budget. The watershed board will now go about the task of raising the $30,000 needed for the equipment, installation, and site preparation for having the ASP in operation for the winter of 2012/2013.
I would like to share some background and history about why a ASP is important and why local government is supporting the annual operation of one. I have included an article from Living Rivers explaining exactly what a ASP is. They talk about the snow pillow operated by the Ministry of Environment at Jump Creek in the Nanaimo River watershed.
When the ministry announced cutbacks in 2002, the Heather Mountain snow pillow in the Cowichan Watershed was decommissioned because it was hoped that the Nanaimo data from Jump Creek would be close enough for Cowichan forecasting. Unfortunately, it’s not even close.
Every summer, the Catalyst Weir goes into operation to ensure there are sufficient flows in the Cowichan River for downstream users and environmental and cultural needs. It is all about how much water flows into Cowichan Lake. How much water can be stored in the lake? How much water can be allowed to escape down river through the gates of the weir? Will there be enough water left in the lake to meet Fisheries conservation targets for salmon in the low water periods in the fall?
The incredibly difficult part of this process is that for the last 10 years since the Heather Mountain snow pillow was cut, the experts have had very little reliable data to forecast how much snow and water was stored in the mountains surrounding our watershed. It is extremely difficult to forecast how much water to allow past the weir during the summer, and still have enough for fish migration in the Fall, when you have no idea how much water and snow is stored in the hills above the lake.
The Cowichan Basin Water Management Plan is recognized as an important tool for protecting our watershed and having a clean and reliable source of water for future generations. There are increasing pressures from downstream users, and if we are going to effectively manage this precious resource, we need to know how much snow is deposited in the hills during the winter and spring.
The measurement of the snowpack in the hills may just be the difference between salmon swimming upstream to their spawning grounds, and people transporting fish in trucks, to save future salmon runs.
I hope you take the time to read the article from Living Rivers called What is an Automatic Snow Pillow Station? We are all stewards of this resource called Cowichan Lake. The more we all know about the tools used to protect this jewel we all love, the greater the chance our children and grand children will grow to love it as we do.
What is an Automatic Snow Pillow Station?
Our B.C. snow pillows consist of three metre diameter bladders containing antifreeze solution. As snow accumulates on the pillow, the weight of the snow pushes an equal weight of the antifreeze solution from the pillow up a standpipe in the instrument house.
This weight of the water content of the snow is termed Snow Water Equivalent. The distance the antifreeze is pushed up the standpipe is recorded by a float connected to a shaft encoder. As well as the vertical standpipe from the pillow, the instrument shelter contains the electronics, consisting of a Data Collection Platform, a shaft encoder which tracks the movement of the float in the standpipe from the pillow, 12-volt wet cell batteries for powering the electronic equipment, and regulators for the externally mounted solar panels for recharging the batteries.
The DCP contains a transmitter to send the recorded data to the Geostationary Operational Environmental Satellite. The GOES then transmits the data to the River Forecast Centre’s satellite data receiving system in Victoria.
On the outside of the instrument shelter are the solar panels for the charging system, and an air temperature sensor. At most snow pillow sites, precipitation gauges and snow depth sensors are also installed. The precipitation gauges consist of a 380 millimetre diameter PVC standpipe varying from 1.2 to 1.8 metre in length, depending on the amount of precipitation expected in the area.
A pressure transducer is mounted externally to the bottom of the standpipe, its output giving a reading of the total amount of fluid in the gauge. To inhibit freezing, the precipitation gauges are “charged” with propylene glycol. A 12-volt pump is used to circulate the fluid inside the precipitation gauge to further inhibit the potential for freezing. The gauges are mounted on top of a 3m high tower to keep them above the snow pack.
The snow depth sensor is mounted on an arm extending from a 6m high tower, and points toward the ground above the pillow. The ultrasonic sensor works similarly to an auto focus sensor in a camera in that it measures the distance from the sensor to the surface below it. As the snow depth increases the distance measured decreases.
All of the Ministry of Environment’s ASPs are installed and maintained by staff of the River Forecast Centre. Our data base and graphs also include ASPs operated by B.C. Hydro and Alcan.