REDUCED WATER levels in Mississippi farm ponds can be both negative and positive. "A very common concern among recreational farm pond owners is the impact reduced water levels have on fish," said Marty Brunson, Extension fisheries specialist at Mississippi State University. "No fresh water entering Mississippi farm ponds means no water to dilute the common nutrients and metabolic wastes from fish. Increased concentrations of ammonia, for example, can be potent and dangerous to fish even at low levels."
The more shallow the water, the more susceptible the pond is to the sun's heat. Shallow water cannot sufficiently protect fish from heat; temperatures greater than 85 degrees stress fish.
With significant amounts of shoreline exposed, there is less pond floor underwater. The soils in this area are a primary refuge and nursery for many aquatic insects which provide a natural food supply to many fish species. With less water, fish also are crowded together. The combination of heavy stocks of fish, shallow water and high water temperatures is bad for the pond's fish.
"Such conditions predispose fish to diseases that can sometimes kill them," Brunson said.
Another concern for farm pond owners is livestock's taking refuge in the pond because of severe temperatures. "Don't allow livestock to access the entire pond. Fence in a section of it for them, because livestock muddy the water and increase the likelihood of bank erosion as they walk in and out of the pond over time," Brunson said.
Not all effects of drought on farm ponds are negative. One very positive aspect is that fertilization can be put off because existing fertilizer tends to remain effective for longer periods of time with no new water entering the pond.
"Drought seasons are ideal opportunities to make shoreline repairs, such as deepening the edges to the desired 18- to 24-inch depth, adding piers, adding gravel beds or fish attractors, and liming the pond in the early fall, since the dry shallow areas are accessible for maintenance," Brunson said.
Those intending to build a pond should plan ahead to minimize drought effects. Be sure the pond size matches the surrounding watershed. For example, each surface acre of ponds in Mississippi needs 7 to 10 acres of surrounding watershed. Having the adequate watershed insures the right amount of water will flow in during rains.
Constructing the pond with the minimum depth of 18 to 24 inches will help insure the pond has adequate water, even during droughts.