Classification of Wetlands and Deepwater Habitats of the United States
Definition. The Lacustrine System
(Fig. 5) includes wetlands and
deepwater habitats with all of the following characteristics: (1)
situated in a topographic depression or a dammed river channel;
(2) lacking trees, shrubs, persistent emergents, emergent mosses
or lichens with greater than 30% areal coverage; and (3) total
area exceeds 8 ha (20 acres). Similar wetland and deepwater
habitats totaling less than 8 ha are also included in the
Lacustrine System if an active wave-formed or bedrock shoreline
feature makes up all or part of the boundary, or if the water
depth in the deepest part of the basin exceeds 2 m (6.6 feet) at
low water. Lacustrine waters may be tidal or nontidal, but oceanderived
salinity is always less than 0.5 .
Limits. The Lacustrine System is bounded by upland or by wetland
dominated by trees, shrubs, persistent emergents, emergent mosses,
or lichens. Lacustrine Systems formed by damming a river channel
are bounded by a contour approximating the normal spillway
elevation or normal pool elevation, except where Palustrine
wetlands extend lakeward of that boundary. Where a river enters a
lake, the extension of the Lacustrine shoreline forms the
Description. The Lacustrine System includes permanently flooded
lakes and reservoirs (e.g., Lake Superior), intermittent lakes
(e.g., playa lakes), and tidal lakes with ocean-derived salinities
below 0.5 (e.g., Grand Lake, Louisiana). Typically, there are
extensive areas of deep water and there is considerable wave
action. Islands of Palustrine wetland may lie within the
boundaries of the Lacustrine System.
- Limnetic. -- All deepwater habitats within the Lacustrine System;
many small Lacustrine Systems have no Limnetic Subsystem.
- Littoral. -- All wetland habitats in the Lacustrine System.
Extends from the shoreward boundary of the system to a depth of 2
m (6.6 feet) below low water or to the maximum extent of
nonpersistent emergents, if these grow at depths greater than 2 m.
Classes. Rock Bottom, Unconsolidated Bottom, Aquatic Bed, Rocky
Shore, Unconsolidated Shore, and Emergent Wetland (nonpersistent).
|Fig. 5. Distinguishing features and examples of habitats in the Lacustrine System. |
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