Secondary Site Locations on Large Reservoirs

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Secondary Site Locations on Large Reservoirs
Issue 1 How to select tributary arms for
criteria monitoring Missouris large reservoirs
are highly dendritic and monitoring should be
limited to the largest of tributary arms.
Issue 2 Where to locate monitoring site within
tributary arms Sites need to be located down-lake
of transition zone but far enough away from main
lake to eliminate influence from main channel.
Issue 3 How to calculate the predicted total
phosphorus value Should the theoretical dam
height be reservoir specific or based on an
average relationship between water depth and dam
height?
Issue 4 Will mode of action at secondary sites
be dependant on the mode of action at dam
site? If the dam site is in Zone A and nutrients
are being held to current long-term mean
conditions, should secondary sites with
phosphorus levels in Zone B be allowed to
increase up to regional reference values?
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Issue 1 How to select tributary arms for
criteria monitoring In order to limit secondary
sites to only substantial tributaries, the
following conditions should be met
A tributary arm must be connected to the main
lake. The main lake is defined as either the
major river stem (ex. Osage River in Lake of the
Ozarks) or in situations where there is no single
dominant river, the open water extending from the
dam (ex. Smithville Lake). A tributary arm
should have 1 ½ miles of length for every 10 feet
of depth at the mouth of the arm. Length is
measured from the mouth of the arm to the point
where riverine conditions become obvious. Depth
at the mouth of the tributary arm should be at
least ¼ the depth at the dam.
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Issue 2 Where to locate monitoring site within
tributary arms In order to avoid locating the
site in the transition zone while reducing the
possible influence of the main lake, sites should
meet the following conditions
A site should be located at least ¼ of the arms
length from the mouth, but no farther than ½ the
arms length from the mouth. Depth at the site
should be at least 1/3 the depth of the tributary
mouth.
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Issue 3 How to calculate the predicted total
phosphorus value The ratio of dam height to water
depth ranges from a low of 1.40 (Table Rock and
Mark Twain) to a high of 7.7 (Clearwater).
Reservoir specific dam height to water depth
conversions should be used
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Issue 4 Will mode of action at secondary sites
be dependant on the mode of action at dam
site? If the dam site is being held at current
water quality levels, then secondary sites should
not be allowed to become nutrient enriched.
If the dam site is Zone A, then all secondary
sites will be held to the highest of the
following the long-term mean or the predicted
phosphorus value.
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Table Rock Lake
James River Arm
Upper Lower Depth (feet)
60 100 Dam (feet) 84
140 TP µg/L 14 10
Whole Section Depth (feet) 40 Dam
(feet) 56 TP µg/L 18
Conversion 1.4
Long Creek Arm
Kings River Arm
Upper Lower Depth (feet)
80 120 Dam (feet) 112
168 TP µg/L 12 9
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Table Rock Lake
Predicted 14 µg/L Long-Term Mean - 27
µg/L Recent Mean 17 µg/L
Predicted 18 µg/L Mean - 21 µg/L
Predicted 12 µg/L Mean 13 µg/L
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Gravois Arm
Lake of the Ozarks
Depth (feet) 70 Dam (feet) 115 Predicted TP
(µg/L) - 11 Mean (µg/L) - 29
Osage River
Grand Glaize Arm
Niangua Arm
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Pomme de Terre Lake
Lindley Creek Arm
Pomme de Terre Arm
10
Stockton Lake
Big Sac Arm
Little Sac Arm
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Truman Reservoir
South Grand River Arm
Osage River
Pomme de Terre Arm
12
Smithville Lake
Platte River Arm
Camp Branch Arm
13
Mark Twain Lake
Indian Creek
North Fork
Middle Fork
Lick Creek
South Fork
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Lake Wappapello
Lost Creek
St. Francois River
Asher Creek Most of section is less than 10 feet
deep.
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Thomas Hill Reservoir
Sinking Creek Arm Maximum water depth 10 feet
through whole section.
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Long Branch Lake
Maximum water depth 10 feet through whole
section.
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Black River
Clearwater Lake
Logan Creek Maximum depth in most of section is
10 feet.
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Lake Taneycomo