It's drought time in the east and other parts of the country, and for pond owners this can lead to trouble. My pond is over forty years old hasn't been this low since it was built. If your pond water level is badly down, here are a few thoughts on the downside of drought plus a few surprise benefits.
The Effects of Drought
As pond water drops, several things can start to go wrong. Water volume and depth decrease, which can result in excessively warm water. Warm water often encourages algae, plankton blooms, and turbidity. For pond owners this summer, poor water quality has stopped many from swimming, which is doubly unfortunate since the summer
was unusually hot.
Warm water can also have a negative effect on fish. As water warms it tends lower in
saturated oxygen content, which can lead to fish kills, especially for cold water fish like trout.
Falling water levels can also affect the pond structure. As shoreline edges become exposed to air and sunlight, clay can crack and compromise the water retaining effect of the earth basin. This may be especially true if a clay liner was added to reduce leakage. Once the water level recovers the cracked clay liner may not be as impermeable as before.
If the pond water level drops below the overflow channel or pipe water circulation is reduced. This can lead to water temperature stratification, with warm water in the top layer, cooler water below. Sometimes the cool bottom layer becomes low in oxygen, which is unhealthy for fish. But if they rise to the top for oxygen, the heat may be fatal.
When the pond stops overflowing, any natural flushing of floating debris out the spillway (leaves, etc.) ends, and that debris winds up adding to the detritus on the pond bottom.
As the water level drops piers and docks on fixed supports stand higher over the water.
Shallower water around docks and piers may be unsafe for diving, with awkward tie-ups for canoes, etc. If the pond has a standpipe overflow, it will become visible, and
stand out like... well, a sore thumb.
Drought can reduce the effectiveness of fire and irrigation ponds. A significant volume loss in a fire pond may reduce firefighting potential, which may be in demand in tinder dry weather. The same goes for irrigation ponds; crops need extra water in a drought, but supply may be limited.
There is one potential upside to lower water levels. Shoreline slopes exposed to sunlight
may kill unwanted weeds. And with edges exposed they can be accessible to weed/cattail/rush removal by raking and digging.
In fact, one traditional pond improvement technique involves draining the water completely and letting the pond lie fallow for a year. This allows the pond keeper to scoop out accumulated sediment which helps restore depth and offers a chance to harvest a load of nutrient rich soil to dress gardens and fields. And expose the basin to aquatic weed reduction by sunlight and frost. Perhaps a bad drought year is an invitation to drain the pond completely and catch up on maintenance and to make improvements.
(See October photo above for example of a droughted pond that offered opportunity to do clean-out and scoop up soil for use in garden.)
Of course, we all want our ponds full and healthy, and there are many possibilities for offsetting drought problems. Next month I'll discuss these fixes, as well as activities to avoid in drought, and some to consider trying.
Photo credit: A. Davis & Jack
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