Coralville Lake Regulation Schedules

The following material was received by C. Newsom on March 19, 2001 from John Castles of the U. S. Army Corps of Engineers, as a replacement for Table C-2, Schedule A, B, and C. of the Regulation Schedule in the Regulation Plan for Coralville Lake.


Schedule A
Normal Flood Control Operation

Pool elevation at or forecast between 683 and 707
Conservation pool Schedule


          Date           Operation
          
    15 Feb - 20 Mar      683 to 679^
    20 Mar - 20 May      Hold 679^
    20 May - 15 Sep      Hold 683
    15 Sep - 15 Dec      Hold 683-686*
    15 Dec - 15 Feb      Hold 683

Notes: ^ Variable draw down based on snow cover, ice, and 30 day climactic conditions coordinated with IDNR
* Dates and elevation of fall pool raise coordinated with the IDNR

Condition Operation
A-1

All Dates
Regulates pool level as nearly as possible without adversely affecting downstream conditions.
Do not release less than mimimum outflow of 150 cfs
A-2

15 December though 1 May
Maintain conservation pool according to schedule without exceeding release of 10,000cfs except as limited by conditions A-3, A-6 or A-7
A-3

15 December through 1 May
Stage at above or forecast to exceed...
Lone Tree 16.0 feet
Wapello 22.0 feet
Reduce release to not less than 1,000 cfs to control flow to those discharges as near as possible during three days of crest at the respected station with due allowance to travel times.
A-4

1 May through 15 December
Maintain conservation pool according to schedule without exceeding release of 6,000cfs except as limited by conditions A-5, A-6 or A7
A-5

1 May through 15 December
Stage at above or forecast to exceed...
Lone Tree 14.0 feet
Wapello 21.0 feet
Reduce release to not less than 1,000cfs to control flow to those discharges as near as possible during 3 days of crest at the respected station with due allowance to travel times.
A-6

All Dates
Stage at above or forecast to exceed...
Mississippi River at Burlington - 18.0
Reduce release to 1,000cfs during seven days corresponding to the crest flow on the Mississippi River with due allowance for travel time.
A-7

Flash Flood: Any date flow at above or forecast to exceed 16,000cfs at Iowa City
Reduce release to not less than 1,000cfs to keep flow at or below 16,000cdf at Iowa City

Schedule B
Major Flood

Pool elevation at above or forecast to exceed 707 feet NGVD
Condition Operation
B-1
Inflow has not Peaked
Determine the pool elevation that would occur at the peak of the inflow hydrograph. Release not more than allowed on table below:

15 Dec - 1 May       1 May - 15 Dec
Elev.    Outflow     Elev.   Outflow
707      10000         707      7000    
708      10000         708      8000
709      10000         709      9000
710      10000         710     10000
711      11000         711     11000
711.1    12000         711.1   12000
711.2    13000         711.2   13000
711.3    14000         711.3   14000
711.4    15000         711.4   15000
711.5    16000         711.5   16000
711.6    17000         711.6   17000
711.7    18000         711.7   18000
711.8    19000         711.8   19000
711.9    20000         711.9   20000
712.0 and above - Gates Fully Open
B-2
Inflow has peaked
Determine the minimum outflow required to utilize the remaining storage below 712.0.
Release that flow or the present outflow - whichever is higher.
B-3
Reservoir Pool Falling
Release outflow established by B-2 until elevation 707 is reached then gradually reduce flows to Schedule A
B-4
Emergency: flow forecast to exceed the control flow established by the U.S. Army Corps of Engineers for public exigency downstream.
Reduce release to keep flow at or below the control flow established by the "Corps".

Schedule C
Drought -- All Dates

Any time pool below conservation according to Schedule A and inflow not sufficient to get to conservation pool.
Condition Operation
C-1
Pool between Conservation and 678.0 feet
Release 150 cfs
C-2
Pool between 677.0 and 678.0
Reduce release to 100 cfs
C-3
Pool below 677.0 feet
Reduce release to 75 cfs
Note: This is a draft. Final wording and form will be added as it is received. CRN--Mar 19,2001