Pitt Lake Tidal Lake EarthCache EarthCache
Pitt Lake Tidal Lake EarthCache
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Pitt Lake, to the north of where you are standing, is one of the
world's largest tidal lakes with a surface area of almost 54 square
kilometers. It is a pristine paradise of blue waters, glacial
topped peaks and lush forests.
Pitt Lake is surrounded by three spectacular provincial parks-
Golden Ears Provincial Park on the east, Garibaldi Provincial Park
to the north and Pinecone Burke Provincial Park to the west.
It is called a fjord lake as it is a valley that is eroded below
sea level by glaciers.
Although Pitt Lake is a freshwater body of water it is connected to
the Pacific Ocean via the meandering Pitt River and Fraser estuary.
The salt water from the ocean rarely makes it to the Pitt River-
Fraser River confluence which is 30 kilometers from the
Ocean.
Tides are caused by the tidal forces of the Moon and Sun acting on
the oceans due to their relative position to the Earth. Though
tides do occur in lakes and rivers it is often such an
insignificant change in water level that it is not visible. Often
the downward flow of water is stronger than the tidal flow or the
very volume of water is not enough to show any change.
The water levels in Pitt Lake can raise over 1 meter in height. It
is the only freshwater tidal lakes in Western Canada and one of
very few in the world.
The ocean tides push up the Fraser River, up Pitt River and into
Pitt Lake causing the water level to rise and fall. The lake then
acts as a temporary reservoir for this Fraser River tidal flow
causing the depth of the Pitt Lake can change up to 1.2 meters. The
flow reverses in the lake due to the changing of the ocean tides
causing the depth of the Pitt River to change as much as 2 meters.
When the tides are moving, strong currents are created in Grant
Narrows, where the mouth of the lake joins the Pitt River. A flood
tide surface velocity of 71 cm/second has been recorded at the
narrows during this reverse flow.
There is much flow variation in these narrows due not only to the
tidal variations but to the low elevation of this area. A large
delta region of sediment is has also been created were Pitt Lake
joins Pitt River by this backwards flow of water at high tide. This
area forms here is essentially a peat bog and a large wildlife
refuge and a perfect spot to canoe.
Pitt Lake, the second largest lake in the Lower Mainland of
Vancouver, is an amazing lake for canoeists, boaters and fishermen
alike. With its prime fly fishing for Coho, Spring and Sockeye
salmon as well as steelhead and its incredible scenery and
wilderness location it truly is a destination to explore.
To log this Earth Cache please:
1. Email me the name of three of the mountains shown on the sign at
the posted coordinates. These mountains create the valley Pitt Lake
is in.
2. Log a picture of you with your GPS with the water in the
background.
3. Describe in an email something you see in front of you that
shows evidence that this area is tidal.
references:
www.nationmaster.com/encyclopedia/Pitt-Meadows,-British-Columbia
www3.interscience.wiley.com/journal/112694829/abstract?
en.wikipedia.org/wiki/Pitt_Lake
www3.telus.net/driftwood/wmapitt.htm
www.pittriverlodge.com/
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