[Ord. No. 17-0244, 4-24-2017]
A.
Jefferson County Has Thirty-Two (32) Watershed Areas. These areas
are associated with the major rivers — Mississippi River, Big
River and Meramec River — as well as with smaller creeks that
have no flow during dry periods. These thirty-two (32) watershed areas
have been condensed into twelve (12) major watershed planning areas:
Belews Creek, Upper and Lower Big River, Glaize Creek, Heads Creek,
Joachim Creek, Lower and Upper Meramec River, Lower Mississippi River,
Plattin Creek, Rock Creek and Sandy Creek.
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The table below summarizes the main characteristics of each
of these major watersheds.
|
|
Watershed
|
Size
(square mile)
|
Headwater Elevation
(feet)
|
Flow Direction
|
Main Branch Length
(mile)
|
Flows Into
|
|---|---|---|---|---|---|
|
Belews Creek
|
26
|
720
|
Northwest
|
9
|
Big River
|
|
Upper Big River
|
125
|
North
|
Meramec River
| ||
|
Lower Big River
|
72
|
North
|
Meramec River
| ||
|
Glaize Creek
|
33
|
850
|
Souteast
|
10
|
Mississippi River
|
|
Heads Creed
|
32
|
800
|
Northwest
|
8
|
Big River
|
|
Joachim Creek
|
125
|
780
|
North
|
34
|
Mississippi River
|
|
Lower Meramec River
|
44
|
Meramec River
| |||
|
Lower Mississippi River
|
32
|
Mississippi River
| |||
|
Plattin Creek
|
62
|
590
|
Northeast
|
18
|
Mississippi River
|
|
Rock Creek
|
30
|
800
|
Southeast
|
12
|
Mississippi River
|
|
Sandy Creek
|
45
|
740
|
East
|
14
|
Joachim Creek
|
|
Upper Meramec River
|
35
|
Meramec River
| |||
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The entire drainage area for Big River is 955 square miles of
which 197 square miles is in Jefferson County. The entire length of
Big River is 138 miles of which approximately 65 miles is in Jefferson
County.
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[Ord. No. 17-0244, 4-24-2017]
A.
Streams can be classified in a few different ways. One (1) way to
classify a stream is by size. In any particular watershed, the smallest
streams that have year-round water and no tributaries are first (1st)
order streams.
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Further along the course, a second (2nd) order stream may join
another second (2nd) order stream to form a third (3rd) order stream
and so on.
|
 |
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When a first (1st) order stream joins a second (2nd) order stream,
the resulting stream remains a second (2nd) order stream. A third
(3rd) order stream is only formed if two (2) second (2nd) order streams
come together. A fourth (4th) order stream is formed when two (2)
third (3rd) order streams flow together and on it goes.
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B.
The basis for determining stream order within Jefferson County is
the blue line or intermittent blue line on the U.S.G.S. Quad Maps.
C.
Small headwater streams originate from a variety of sources —
snow melt, surface runoff, a lake outlet or ground water which surfaces
as springs. These headwater streams are classified as first (1st)
order and second (2nd) order streams. They are no more than a few
feet wide. These headwater streams have a relatively straight V-shaped
channel. The substrate or stream bottom is composed of boulders and
cobblestones.
Downstream, in the middle reaches of the river system, some
tributaries have entered the stream and added to the flow. The wider,
bigger and deeper U-shaped channel is now a third (3rd) or fourth
(4th) order stream. The middle river reach has a meandering or braided
channel with a substrate or bottom of boulders, cobble and gravel.
Progressing downstream towards the streams mouth, more tributaries
have entered and added more flow to create a mainstream river. The
channel widens and meanders in wide arching loops. The bottom is gravel,
sand and mud.
At its mouth, the river empties into another body of water and
carries its remaining load of sediment, debris and other substances
with it. The water body can be an estuary, a lake or a larger river
system.
A watershed is one (1) interconnected land/water system. An
action in one (1) area of a watershed, even far up into its headwaters,
can affect what happens in distant areas downstream. Any changes we
make to the land surface or to the vegetation also changes some aspect
of the hydrologic cycle.
