September 18, 1980
TO: JOHN HEUER, HYDROLOGIST, REGULATORY DIVISION
FROM: J. EDWARD CURRENT, ASSISTANT STAFF ATTORNEY ^
RE: Water Resources Law of 1957 "Average Minimum Flow"
Former 373, F.S., provided that DNR could authorize the capture,
storage and use nf water of any watercourse only in excess of
"average minimum flow" at the point of capture.
When required for such authorization, the law required that the
Division of interior resources determine and estcblish the
average minimum flow for each month, January through. December,
for the given watercours- at a given 0oint thereon. The average
minimum flow as used in Lhe law "shall he the average of the five
lowest monthly mean discharge for each moith, January through
December, occurring during the past twenty years of natural flow.
This Law applied in Manatee County in the 1960's. The SWFWMD
Rules were not in effect, therefore, the average minimum flow
established for the Manat-e River "at a given point" near the then
proposed dam would have been higher than Section 40D-1.601(2)
criteria would provide. It is important that this be realized
in any evaluation of the applicable minimum flow.
I understand that Bob Perry is going to c&alulate a Minimum Rate
of Flow for the Manatee River at the Manatee Reservoir using USGS
data from a former stream gaging station (which is now- under the
reservoir) which has records for the period of "natural flow"
between 1945 and 1965.
Please ask Bob to calculate first using the statutory definition
of average minimum flow recited above. Also, that rhe "given
point" be at the station.
The multipliers (USGS 1.4 and MCUS 1.6) should be ccplied to
average minimum flows thus established.
If SWFWMD Rule Section 40D-1.601(2) is used at all it should only
be for informational purposes.
cc: D. R. Feaster
3. T. Ahern
L. M. Blain /
G. W. Kuhl