Standing Water lakes and ponds

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Standing Water lakes and ponds Lakes result
from either barriers to drainage or when
depressions (or excavations) form along a
drainage system Majority of lakes are found in
glaciated areas and are formed by glacial
action Others are formed in river channels
(oxbows), by geological faulting, volcanic
action, or sea level changes
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Beavers form ponds by blocking drainage and then
excavating the basins and seal the dam with the
mud they dig uplakes and man-made reservoirs are
formed in much the same wayexcavation and
impoundment.
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Glacial lakes
The vast majority of lakes in the world occur in
glaciated areas74
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Glaciers can form lakes in the following
ways Ice can impound the flow in a drainage
system The flow can be blocked by glacial till
or moraines Ice flow can scour or deepen a
basin Ice blocks in till can melt out to form a
kettle or pothole which then fills up with
seepage or surface flow
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Moraine dams tributary stream
Moraine
Mountain glacier
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Moraine
Glacier recedes

• After the mountain glacier recedes a large lake
  can fill the scoured out valley.
• The moraine damming the lake outflow maintains
  the level

Glacier recedes
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Moraine at the outlet of Upper Waterton lake
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• A Proglacial lake
• A river is blocked by ice, usually from a large
  continental glacier
• the water flowing toward the glacier forms a
  large lake at the glacier margin

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Proglacial lakes

• Following the retreat of the last
• glaciation most of the Canadian landscape
• was covered by proglacial lakes
• Species tolerant of coldwater (salmonid
• and coregonids) became very widespread.
• Opportunities for dispersal of
• cool and warmwater species were much more limited
• because these water bodies disappeared with the
  ice.

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Proglacial lakes in southwestern Alberta and
Montana (around 12,000 Bp)
western extent of the continental glacier
Probable Waterton glacial lake at the height of
the Wisconsin glaciation gt12,000 yr bp.
Present Waterton lakes
This lake would have been fed by the all of the
tributaries of the Oldman system
This lake probably served as a major refugium
from which fish and invertebrates colonized the
SSRB, after the ice age. Genetic studies
indicate that many lake trout populations across
western Canada came from this glacial refugium
Eastern extent of the cordilleran glaciers
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Waterton Lakes have a similar originBoth
Waterton and Memphremagog have contain glacial
relict animal species in their deep waters.
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Freshwater mysid shrimp are important glacial
relicts and have a restricted range because of
this. They have been introduced to many lakes
because fisheries managers thought that this
would improve fisheries yields This has largely
backfired because Mysis tends to compete with
epilimnetic zooplanktivorous fish, and because of
their vertical migrations are difficult for these
fish to consume. Most of the mysids for the
introductions to other western lakes came from
Upper Waterton Lake