L.D.W.F.
Announces Lake Martin Drawdown
Posted:
9/6/05
The Louisiana Department
of Wildlife and Fisheries Inland Fisheries Division has scheduled
a Lake Martin drawdown to improve water quality conditions
and buttonbush and cypress tree recruitment.
LDWF recommends
lowering the lake on Sept. 19, 2005 and full replacement of
the water, which will be pumped in from Ruth Canal, by Jan.
31, 2006. This drawdown will insure that fish-spawning habitat
will be accessible for spring production. While the drawdown
may impact navigation in parts of the southern end of the
lake for duck hunters in late fall/winter, it is anticipated
that hunting on the majority of the lake will not be affected.
In the fall of
2002 a drawdown of Lake Martin was cut short due to a tropical
storm and hurricane Lili in October that filled the lake with
excessive amounts of rainfall. In 2003 and 2004 the conditions
were suitable and the drawdowns were successful, which led
to stable and satisfactory dissolved oxygen levels and visible
new buttonbush growth.
Over extended periods
of time water quality in the lake has suffered due to nitrogen
inputs from the extensive bird rookery and the impoundment
of water by the levees. The high nutrient levels have encouraged
excessive growth of aquatic vegetation that resulted in a
depletion of oxygen from the water column.
A water control
structure was put in place in late 2001 on the southeast end
of the lake. The structure is designed to release the main
pool of nutrients, near the rookery, into the adjacent 6,400-acre
Bayou Tortue Swamp, largely owned by The Nature Conservancy.
The existing swamp vegetation will take up the drained nutrients.
Exposure of lake bottom sediments to oxygen will allow nitrogen
that is trapped in sediments to be released into the atmosphere.
Since the rookery is relatively shallow, a partial drawdown
of 2-3 feet would greatly improve water quality conditions.
In addition to
improving water quality, a drawdown will expose the lake bottom,
which will serve to control aquatic weed infestations. This
weed control will improve fish spawning and survival of the
eggs and facilitate access for recreational and commercial
use.
The goal of the
drawdown is to restore the lake ecosystem to a condition that
supports a healthy fisheries and wildlife habitat. It is anticipated
that restoration will require drawdowns for several successive
years along with careful monitoring of water quality, fisheries
and vegetation by researchers at the National Wetlands Research
Center and staff biologists with LDWF.
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