Drought puts the heat on
poorly constructed ponds
By Robert Burns,
Texas AgriLife Extension Service
OVERTON, TEXAS - “You know it’s dry when your fish have ticks,”
jokes Dr. Billy Higginbotham, Texas AgriLife Extension wildlife
and fisheries specialist.
Jokes aside, it’s a serious matter as water levels drop for the
owners of the more than a million private water impoundments in
Texas. Channel catfish, bluegill and largemouth bass must
survive both a shrinking habitat and dropping water-oxygen
Dropping oxygen levels can be a problem during a hot Texas
summer even when there’s normal rainfall. But there’s nothing
like a drought to highlight a poorly constructed pond and
magnify the potential for fish kills, Higginbotham says..
“It’s hot and dry even by Texas standards, but the ponds that
show the problem first and foremost are those that have either
very small watersheds or those ponds that were built on marginal
soil,” he said.
A small watershed means there is not a large enough area
surrounding the pond for sufficient runoff to maintain water
levels, even during years with average rainfall, Higginbotham
explained. To hold that runoff, the soil the pond is situated in
should contain enough clay.
“These are important construction concepts for landowners to
remember whether they are watering livestock or if fish are an
important recreation use of that pond,” he said. “Fish remain a
primary concern to many owners of small ponds, and there are
more than a million private impoundments found statewide.”
Obviously, Higgibotham said, when ponds are not much more than
mud wallows, there’s little that can be done about saving fish.
“Certainly, when pond levels reach this point, I hope they have
done something about fish populations already, hopefully
harvested them,” he said.
But even if a pond is well-constructed and its water level has
only dropped a foot or two, it still behooves pond owners to pay
attention to fish management and water oxygen levels,
“In any case, we want to avoid trying to carry more than a
thousand pounds of fish per surface acre during the warm
months,” he said.
A thousand pounds of fish per surface acre of water is a good
rule of thumb for a number of reasons.
“As water temperatures increase, the ability of that water to
hold oxygen decreases, so typically, the hot summer months are
when oxygen depletions are most likely to occur,” Higginbotham
Also, as water temperature rises, the metabolic rate of fish,
being cold-blooded animals, will increase, and with that
increase comes a need for more oxygen. But under sunny
conditions and moderate temperatures, aquatic plants - mostly
single-celled algae - will produce enough oxygen to somewhat
offset the low oxygen concentration levels of warm water.
Cloudy days have been rare during the 2011 drought, Higginbotham
noted, but when skies are overcast, photosynthesis is decreased
and oxygen levels drop further.
“If the pond is too heavily stocked, fish can run into an oxygen
debt,” he said. “Hot weather can even bring about oxygen debt in
moderately stocked ponds.
“Furthermore, small ponds that are intensively managed for
high-standing crops of catfish at or above 1,000 pounds per
surface acre are going to be among the first ponds to experience
oxygen shortages as water levels drop.”
Higginbotham said he has found that many pond owners
over-estimate the surface acreage of their ponds by a factor of
two or three.
There are simple methods to determine the size of a pond, he
said. If the pond is more or less rectangular, the simplest way
to determine its size is to measure the length and width in
feet, then multiply one measurement by the other to get surface
area in square feet. Divide this number by 44,000 to get the
approximate area in acres.
As an example, a relatively square pond measuring about 200 feet
on each side will have 40,000 square feet of surface area, or
about one acre.
Calculating a round pond’s size is a little more complicated.
Divide the distance across the pond by two, square the result,
then multiply that number by 3.14.
Once the approximate surface area is determined, the next step
is to determine the pounds of fish in the pond, Higgibotham
“Usually, the pond owner knows how many catfish were originally
stocked in the pond and has a pretty good idea how many have
been removed since stocking,” he said. “By catching a few fish
and weighing them, an owner can estimate the total pounds of
fish in the pond.”
Pond owners who suspect low oxygen concentrations should monitor
their ponds closely, even if their stocking levels are 1,000
pounds per acre or less, Higginbotham said.
“Visit the pond shortly after daybreak,” he said. “If fish are
crowded up at the surface at first light, that’s a pretty good
indication that you’ve got low-oxygen levels.”
If this is the case, pond owners should either immediately
harvest fish to reduce the stocking level or aerate that water,
“Aerate with a pump or boat motor just to get over the hump and
through the immediate emergency in order to raise the oxygen
levels, so you don’t lose an entire pond of fish.”
Cheer camp at the Lodge
Mabank High School varsity and junior varsity cheerleaders and
mascots gather at the UCA cheerleading camp at Great Wolf Lodge
in Grapevine June 27-30. Chris Zitko and Kurt Clark each
received an invitation to try out to join the UCA staff as
cheerleaders next spring.
Monitor Photo/Kerry Yancey
Mabank High School varsity cheerleader Jordan Koskelin and
mascot Dakota Thompson each received an "All-American" ranking
at the UCA cheerleading camp at Great Wolf Lodge in Grapevine
June 27-30. The "All-American" ranking puts both in the top 10
percent of cheerleaders and mascots in the nation.