and Losing Streams
Scenario: No. 1
Scenario: No. 2
Scenario: No. 3
Definition of a sinking watercourse
To be considered a sinking watercourse, a watercourse must sink
into the subsurface at a distinct sink point and possess one or
more of the following characteristics:
- Poorly or non-defined channels (including flow over an organic
- Exhibit no evidence of scouring or alluvial deposition
- Flow on the surface for less than 100 metres.
As a minimum threshold, a sinking watercourse must follow a confined,
linear drainage course with a distinguishable cross-sectional
low point, accompanied by the presence of hydrophytic vegetation
(plants that thrive in saturated
Sinking watercourses are considered to be less of a management
concern than sinking streams because of their lower potential for
impacting significant recipient karst features. For example, sinking
watercourses would typically exhibit low-energy water flows, lower
transport potential, and intermittent or ephemeral flows. Nevertheless,
sinking watercourses have the potential to transport sediment,
fine organic material and small woody debris into the subsurface.
For this reason, the management objectives for sinking watercourses
are the same as those for sinking/losing streams.
Recommended best management practices
Where a significant recipient karst feature receives water from
a sinking watercourse, the watercourse
should be managed in a manner consistent with the management
objectives for sinking
and losing streams.
best management practices
are recommended within an appropriately sized riparian management
- Retain windfirm trees with roots embedded in the watercourse
- Fall and yard away from the watercourse to the fullest extent
- Avoid yarding across the watercourse.
- Remove slash and debris that inadvertently enters the watercourse.
- Retain windfirm non-merchantable trees and other windfirm
vegetation (understorey, shrubs, herbs) within 5 metres of the
- Retain windfirm wildlife trees.
These recommended practices, or others deemed appropriate to achieve
the management objectives, should be applied
for a minimum of 100 metres upstream
of the recipient
feature, or to the point where the watercourse is no longer
readily identifiable, whichever is shorter.