October 13, 1982
TO: R. V. McLean
FR: L. M. Blain
RE: Major CUP's from streams
The new methods for analyzing the yield of in-stream and off-,
stream reservoir system looks interesting. I feel that this
method does have merit. My concern, however, is that the
parameters are not changed after the system yield is developed
because the data would then no longer be accurate. For example,
contours of the stream bed may become modified, flow rates may
become restricted or more open, or the drainage basin may be
enlarged or reduced by drainage ways.
Other than my concern expressed above, I am impressed with the
potentiality for this new method as a useful tool in water
supply and CUP stipulation analysis.
,/ LMB/mm /
september 29, 1982
TO: W. D. COURSER, Director, Resource Regulation Department
L. M. BLAIN, General Counsel
FROM: R. V. McLEAN, Supervisor, Project Development and Management a M----
RE: Major CUP's from Streams
Over the past couple of years, we have done a great deal of work on the analysis
of potential water supplies from both surface and ground water sources in the
Manasota and lower Peace areas of the District. In the case of ground water
we've used the standard model approach employed by the District, but no such
standard method was available for withdrawals from streams. As a result, we
developed a method to analyze the yield of both instream and offstream reservoir
systems as well as those systems used in combination.
The method involves the following general steps:
1. Determine the historical stream flow at or near the point of withdrawal.
This sometimes requires the development of transfer data from nearby
streams with similar watershed characteristics and adequate record
(this is an established practice).
2. Using the historical record as base data and a standard synthetic
stream flow generator model, develop extremely long term synthetic
flow records. This statistically derived data covers the range of
monthly (or seasonally, etc.) flows that are probable based on actual
flow. This method gives more reliable results than the shorter term
actual flow data.
3. Develop a model which simulates the physical water supply facility.
The model includes such items as raw water storage capacity, pump-
ing capacities, evaporative loss, rainfall gain and ground water
losses and gain, and mathematically simulates the actual supply
4. Streamflow plus any constraint or combinations .of regulatory constraints
aQre_ ajied to give a "developable" yield. There is unlimited flexi-
bility in the application of these constraints and they can include
minimum flows, upstream withdrawals or any other possible constraint.
5. The developable yield is used in the system simulation to determine
a 95% dependable system yield with the given constraints.
This methodology allows rapid and precise analysis of a system's yield based on
the system, stream flow and any other constraint we wish to analyze. It can
provide a powerful and flexible tool not only for water supply analysis, but -
W. D. Courser
L. M. Blain
September 29, 1982
very importantly a standarized method for the analysis of potential CUP
stipulations. Every step of the process can be scientifically explained and
justified for use in the CUP process.
If ou believe t Mthod has merit, and would wish to pursue it further, just
us believe h tcan be refined and documented so that
it ould be applicable to all streamflow withdrawals in the District. Copies
of two recently completed reports are attached which illustrate the potential
instream and offstream applications. Please review the offstream report since
it is still in Draft, and let me know what you think. If you have any comments,
please get them to me by Ootobgr th
This process offers an excellent opportunity for the Resource Management
Department to assist in the regulation effort.
cc: Gary Kuhl