Most agricultural lands have been treated with pesticides. However, most of these lands and water sources are not considered contaminated.
Today’s pesticides have a much shorter half-life in the environment and are considered safer than earlier pesticides.
Chlorinated hydrocarbon insecticides such as toxaphene, dieldrin and endrin were widely used in agricultural production before 1975.
The recommended maximum concentration of toxaphene in soils to be used in aquaculture is 0.5 ppm. The combined concentrations of dieldrin and endrin should not exceed 0.1 ppm. These are general guidelines and have no regulatory status.
When selecting a site for aquaculture, the main concern is soils in low areas where runoff collects, sites previously used for pesticide storage or disposal, and areas where aerial or ground application equipment was loaded or washed.
These areas should be tested for residual pesticides because contaminants in the soil could affect biological processes within the pond or be discharged with effluents.
Typically, contaminants accumulate in the top 6 inches (15 cm) of topsoil, so samples should be confined to this depth. Pesticide analysis can be conducted by private or state chemical laboratories.
If contaminants are found, the affected soil layer should be removed from the site or used in areas that will not come in contact with pond water (e.g., levee cores, building pads, or access ramps).
Sites in rural areas have a lower risk of contamination than those in urban areas. Effluents from urban waste water treatment plants and industrial facilities can contaminate surface waters, and seepage from hazardous waste holding ponds at industrial facilities can contaminate groundwater sources.
Access:
Ponds must be accessed year-round. Roads and ramps to levee tops must allow vehicular traffic for equipment maintenance, water quality monitoring, feeding, and harvesting. Large-volume facilities must be accessible with multi-axle vehicles, so roadways and levee tops must be wide enough to accommodate these loads.
Access to electrical service must also be considered. Most electric companies will provide only a limited number of poles and a limited amount of power line from existing infrastructure before additional charges begin.
The farther the site is from existing power lines, the more expensive the project will be. If wells will be powered by electric motors, or if aerators larger than 1 horsepower will be used, three-phase electricity may be required. This may eliminate some potential sites because single-phase is the predominant electric source in rural settings.
Consider the potential effects of any rights-of-way for power lines, gas pipelines, or railroads that cross the property. Utility rights-of-way are usually sprayed routinely with herbicides to control vegetation. Maintenance for gas pipelines could require the draining of ponds.
Power lines should be high enough that they are not hazardous for loading equipment or feed truck deliveries. Railroad crossings could lead to equipment/train collisions or limit access to ponds during long train passages.
In the site selection process, it is important to allocate land and resources for ancillary facilities such as hatcheries, headquarters, shop, storage, and housing for employees. If the production system is successful, the owner may seek to expand the operation.
Will there be access to adjoining or nearby sites for this expansion? Expansion of a facility across sites distantly removed from a centralized location can lead to management concerns and additional transportation costs.
Environmental concerns:
Several state or federal agencies may have jurisdiction over land use and pond construction. Contact the local NRCS offce for guidance. Additional site review may be required by the U.S. Army Corps of Engineers, which administers and enforces provisions of Section 404 of the Clean Water Act. Section 404 regulates, among other things, the conversion of wetlands to farming, including aquaculture ponds. In some areas, land-use zoning may preclude agriculture in general or aquaculture in particular.
Consider how pond construction and operation may disrupt activities and resources downstream. Construction of facilities and access roads could alter the natural water flows needed to maintain surrounding habitats and downstream environments such as wetlands and groundwater aquifers.
Construction of ponds can lessen or increase the potential for flooding by altering the natural hydrology of the watershed, depending on the size (i.e., storage volume) and position of the ponds and drainage patterns.
Also consider how aquacultural effluents might affect receiving waters, and whether you will need to retain these effluents in constructed drainage systems before discharge. Discuss the frequency of discharge and allowable discharge limits with environmental resource agency personnel.
Avian predators can cause significant losses and spread diseases. Contact your USDA/APHIS Wildlife Services office for information on known rookeries or feeding areas of predatory birds near the potential site. Avian predation may be mitigated to some extent by grouping ponds with vulnerable life stages near areas with lots of human activity.
Author:
Jimmy L. Avery
