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C1 Canal & MS-1 Spillway Water Flow Problem
| C1 Drainage Area & Map |
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| Includes proposed Rediversion Plans |
Overview of C1 Canal Issue
The MS-1 is the water control structure
west of Turkey Creek Sanctuary that lets water into Turkey Creek from the C1 canal. The C1 canal is the large canal,
which goes under Babcock between Port Malabar and Malabar roads. This canal goes almost all the way west to the St.
John's River and drains all the surrounding areas of Palm Bay (100 square miles) into Turkey Creek via the MS-1. Large
amounts of water that would normally go into the ground or into the St. Johns River enter Turkey Creek from the C1.
The
MS-1 uses something called "Amil gates" which open very quickly when water levels in the C1 canal rise high. This causes
a large "wave" of water to push through our creek, pushing large amounts of sediment along with it. These sediments not
only impact the quality of our water, but also fall out and lead to shoals (sandbars) which impede our boating access. Draining this large area also causes our creek to always have suspended sediments,
blocking sunlight, and preventing plant growth on the bottom of the creek. This of course, leads to an impact on all
other wildlife. Historically, Turkey Creek held "clear" water, lots of submerged
vegetation, and deep channels. The water color was still tannic, but did not contain all the suspended sediments that
it does today.
Impact to Turkey Creek and
IRL
Turkey
Creek's drainage area was expanded 10 miles beyond its natural western boundary taking in about 98 sq mi of the Upper St.
Johns River Basin floodplain and marshes. This expansion began in the 1920's and continued well into the 1960's under
the authority and management of the Melbourne-Tillman Water Control District (MTWCD). As a result, the Turkey
Creek watershed was effectively enlarged seven-fold.
Over
90% of the annual volume of fresh water and 68% to 80% of the annual loadings of nutients (N and P) and suspended solids that
are discharged through Turkey Creek are contributed by the MTWCD's primary canal. These unnaturally large volumes of
fresh water and pollutant loads released from C-1 are impacting salinity and water quality and, in turn, the seagrassses within
a 10 to 20 sq mi area of the adjacent Lagoon. (Source: Indian River Lagoon Surface Water Improvement & Management (SWIM) Plan 2002 Update & Turkey Creek Blueway/Greenway Management Plan).
These
large un-natural releases of water into Turkey Creek are also causing massive damage to the upper creek. Within another
year or two, most of the bends in the upper creek will be by-passed. (Reference "Upper Creek Oxbow Damage" slides.)
MS1 Water Flow Monthly Charts Summary (Click on Month & Year Below
to see Charts)
The FOTC monitors Chart 1 to see if the discharge
from the MS1 water control structure exceeds the Critical
Discharge Range and if so by how much and for what duration of time. When
we exceed the Critical Discharge Range, we establish flow rates in Turkey Creek that are capable of moving the sediments in
the creek to areas downstream where it settles out and forms shoals (sand bars). We
then go to Chart 2 to see if the water elevation upstream from the MS1 structure has reached or exceeded 9 feet, and if so
for how long. When the water elevation upstream reaches levels of about 9 feet,
this usually causes both Amil gates (two of the four gates controlling water flow at the MS1 structure) to open and release
large quantities of water through the structure. This sudden and large release
of water is what causes the flow rates in Chart 1 to exceed the Critical Discharge Range. A storm event in the area is usually the cause for
this chain of events (1st the storm, then the water elevation of about 9 feet upstream of the MS1 structure, and
then flow rates in excess of the Critical Discharge Range that is the result of the Amil gates opening).
The data which is provided to FOTC from the Melbourne
Tillman Water Control District, is provided below; along with a cover letter describing what occurred during the month.
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June 2003
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July 2003
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(Cover Letter requires Microsoft Word or the free Viewer)
EXPLANATION
OF CHART 1
VERTICLE SCALE: This scale usually goes from 0 to 1200 cfs (cubic feet per second)
but can change if the discharge during any part of the month goes over
1200 cfs. The dark black line gives the discharge from the MS1 water control
structure in cfs. The dashed blue line gives the cumulative rainfall for the
month as measured at the MTWCD (Melbourne Tillman Water Canal District) headquarters.
The same scale is used for rainfall but 200 is equal to 2 inches and 1200 is equal to 12 inches.
HORIZONTAL SCALE: Gives the day of the month
The top left corner of the
chart gives the Critical Discharge Range (500 to 700 cfs), the Controlled Discharge Range (200 to 300 cfs) and the Base Flow Range (25 to 116 cfs). The Critical Discharge Range is outlined on the chart with two horizontal red lines.
Notes are usually put on
the chart in different colors to explain if weather related or man related events causes a change that is reflected by the
graphs.
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EXPLANATION
OF CHART 2
VERTICLE SCALE: This scale usually goes from 0 to 10 and reflects feet when measuring water elevation and inches when
measuring rainfall. The dark black line indicates the water elevation upstream
of the MS1 structure. The blue line indicates the water elevation downstream
of the MS1 structure. The straight red line is the elevation that MTWCD is trying
to control the water to on the upstream side of the MS1 structure. The dashed
purple line is the cumulative rainfall as measured at the MTWCD headquarters.
HORIZONTAL SCALE: Gives the day of the month.
Notes are usually put on
the chart in different colors to explain if weather related or man related events causes a change that is reflected by the
graphs.
EXPLANATION
OF SHEET 1
Sheet one shows the multiple
readings taken each day, some of which is used to create Charts 1 and 2. It has
other data that is not graphed like NOAA rainfall, radial gate settings, amil gate settings, flow rates from individual gates,
etc.
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