Baggs

There are more than 4,000 ponds in Denton County today. The last nationwide estimate in 1980 was 2.1 million across the U.S. For years, many farmers and ranchers built ponds for livestock water and irrigation.

More than 75 percent of the livestock in the county depends on surface water from ponds for daily survival. With the higher demands of water and the effects of drought still in our minds, more landowners are considering digging a private pond.

However, the purposes for building these ponds have changed in the more urban environments. Ponds are serving more of a variety of purposes, such as fire protection, landscape aesthetics, conservation, wildlife habitat and recreation.

Recreation activities include swimming, fishing or just sitting under a shade tree on the bank, watching the kids on a hot summer day.

During these hot summers, cloudy days present the greatest possibility that fish deaths will occur. The majority of these fish die-offs can be attributed to oxygen depletion.

Warm water cannot hold as much oxygen as cool water, yet fish need more oxygen as their metabolisms increase. A pond usually can carry 2,000-3,000 pounds of fish per acre during the winter months, but not during the hot summer.

To check for oxygen depletion, observe the pond at daylight — when the oxygen level is at it’s lowest. Fish will be striking the surface of the water to gulp oxygen. Typically, larger fish will be the first to exhibit signs of oxygen stress.

Oxygen in the water comes from absorption at the surface level and photosynthesis of aquatic plants. Still, hot days in succession will reduce photosynthesis and, therefore, oxygen production.

Applying aquatic herbicide treatments during hot weather may kill off vegetation too quickly, resulting in oxygen depletion. Excessive feeding or fertilizing will result in nutrient decomposition or phytoplankton die-off, also causing oxygen depletion.

Many steps can be taken to correct this problem, including aeration and reducing the amount of fish load in the pond to less than 1,000 pounds per acre.

An easy aeration process involves submerging back end a boat on a trailer in a fixed position and using the motor to circulate the water.

Fresh water from a well may also be added, but be sure it is properly aerated before entering the pond.

A circulation pump can be used, but set the intake near the pond surface. Pumping water off the bottom and spraying it over the surface only worsens depletion of oxygen.

But, first and foremost, watch for signs of oxygen depletion and take action in time to avoid a fish die-off as the temperature rises.