Agricultural Nutrient Removal
C. W. SHEFFIELD, Pollution Control Officer
Orange County Pollution Department
Orlando, Florida
INTRODUCTION
For many years man has been diverting water for irrigation of his land. This has
resulted in many productive acres of valuable farm land. This practicing of land
irrigation has unfortunately caused many problems throughout the country. The
problems associated with the discharge of agricultural waste into the receiving waters
are as follows: 1) increased nutrient load; 2) discharges and fallout of pesticide
material; 3) water management problems from sporadic water uses; and 4) increase
of mineral content.
In Florida the use of surface waters in irrigation of agricultural lands has resulted
in providing thousands of acres of very productive and profitable grove and truck
farming lands. Each using surface waters in a slightly different manner, but both requiring tremendous volumes.
This paper will discuss the quantity, quality and removal of nutrients from the
organic soil farming water discharge. The farms to be reviewed are located on the
north shore of Lake Apopka. This truck farming operation was created as a municipal corporation by the passage of a special act in 1941, Florida Legislation (1). This
act enabled the farming interest to dike off approximately 15,000 acres of the lakes
rich peat bottom, pump the water out, and start a vegetable growing operation.
The major crops are corn, celery, radishes and leaf crops which are grown
throughout the entire year (2).
This farming area is broken into two areas; 9,000 acres comprising the Zellwood
Drainage District on the north and northeast shore of Lake Apopka; with another
6,000 acres owned by eight individuals on the Beauclair Canal west and east banks as
shown in Figure 1.
On an average the water level in Lake Apopka and the canal is held between
66.4 and 67.2 MSL and the farm land surface elevation lies between 62.5 - 64.0 MSL
(3). The United States Geological Survey records indicate a low water elevation of
64.3 MSL was observed in August 1956.
The earthen levee, separating Lake Apopka from the farms, has a maximum
elevation of 70.0 MSL. Water levels in the lake are controlled by the Beauclair Lock
and Dam. The existing lock and dam was completed and in operation in 1955.
Prior to this date, lake levels were maintained by a temporary wooden structure.
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