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Storms and Ponds
Last Updated: 9/9/09
Rain and Flooding
Snow and Blizzards
I welcome input from others with their ideas for ponds during bad weather.
One of the biggest storm-related problems comes from rain. A little rain, especially during a
drought, is a good thing. A foot of rain over a day though can cause all sorts of problems for
The first problem involves water chemistry. Lots of rain will often lower the pH, alkalinity, and
hardness of the pond, making it closer to rain water. Chemical additives can be added to bring
those back up. Baking soda (sodium bicarbonate) is a quick way to bring up the alkalinity. Rain
may be acidic in some areas. If the pH crashes too much during a heavy rain incident, fish may
die from that.
The next problem is oxygen. Rain water is low in oxygen. If it rains too much, the oxygen level
may fall to dangerous or even deadly levels. Full aeration from air stones, waterfalls, fountains,
etc. should be maintained during heavy rain. If the power goes out, a battery-operated air pump
or generator is a good idea. For more on rain and water in general, see my water page.
Another problem is dirt, chemicals, and debris coming into the pond from a higher level in the
land. It helps to situate the pond at the high point in the yard. For prevention of dirt going into
the pond and how to deal with it if it does, see this section.
The final, and perhaps biggest problem, is overflow. If there is a lot of rain, water will have to
find a way out of the pond. All ponds should be built with an overflow built into them. The
overflow should be made to minimize fish and other animals going downstream with the water.
A grate, rocks, etc. could be associated with the overflow area. The overflow has to be at the
lowest point in the edge of the pond and head to a lower grade. It is a good idea for ponds to be
at the high level of the yard and not at the lower level. Even so, with really bad rain, the
overflow will not be able to handle it, and water may come up over the edge of the pond, with
water and associated animals going downstream. During hurricanes or other heavy rains, fish
have been known to end up leaving their ponds. To help find them, float something light like a
piece of plastic on the water leaving the pond if it's still flowing and follow it downstream.
Otherwise, simply walk downstream searching for water with fish or stranded fish. If kept wet,
koi and goldfish may live for a while after a storm washes them away.
Wind usually causes the most destruction and power outages during storms. Luckily, it is less of
a problem for ponds (aside from taking out power). Sometimes debris will end up in ponds from
the wind which needs to be removed. The biggest problem that results from wind is during the
winter. Wind will strip a pond of its heat quickly in the winter. A pond can flash freeze when
wind blows through as the temperature drops. Fish and other animals who stay near the surface
may freeze into the ice. Contrary to what some people say, they cannot revive when it melts.
Keep in mind that a pond may freeze quickly during high winds. While my 1800 gallon pond
normally has a slowly expanding ice cover, during high wind and temperature dropping days, I
have had the pond go from ice free to 90% ice covered over night. Wind may create ice quickly
on an active waterfall and divert water. The wind may also interfere with de-icers. Placing
boards, plastic storage tub lids, and such over the de-icer to create a pocket with no wind will
help a de-icer to continue to function. For more on de-icer problems associated with wind, see
my winterizing page.
It is often hard to predict hail or prepare for it. If you can, use boards, plastic storage tub lids,
and so on to cover over the pond where there are floating waterlilies and other plants. The
biggest problem with hail is that is puts holes in waterlily leaves and other plants. Usually, all
the leaves are affected. For the health of the plants, it is best to wait until the damaged leaves
show signs of rotting to remove them. By then, hopefully some undamaged leaves will have
come to the surface.
I have not heard of many lightning strikes over ponds but it certainly can happen. Lightning
prefers to strike over land but may also hit right next to a small pond. All electrical outlets
should have ground circuit fault interrupters to shut down the power to the pond if it is hit. Fish
may be killed if the pond is struck. Fish may also be dazed so be sure they are dead before
removing them. Lightning in and around the pond may destroy electrical pumps and equipment.
Small amounts of natural or man-made electricity may cause fish to develop a bend in their
spine. There are other causes for bent spines as well (fish tuberculosis, dietary deficiencies,
physical injury, and genetic abnormalities).
What to do in preparation for a hurricane:
- If the pond is under a few hundred gallons, and the hurricane is supposed to be bad, consider
bringing the fish and maybe other animals inside to aquariums until after the hurricane
- Get a battery-operated air pump or generator if you do not have one. If you have a battery-air
pump, and the power is very likely to go out, set out the air pump before the storm so it is going
when the power goes out. Protect the air pump with something like a ziploc bag, cinder block
(pump inside, block on top of that), or something to keep water out of the air pump.
- Cover the pond with netting for larger ponds (to keep out leaves, small branches, etc.),
boards (with room for air exchange) for smaller ponds, or anything else you can find. Weight
those down with rocks, bricks, etc. so they stay in place.
- If a lot of rain is expected, and the pond might flood, bail it down some. You can also use
the pond pump to pump out some water.
During the hurricane, stay inside for your own safety!
After the hurricane passes:
- Get power up as soon as you can. When there is no electricity, try to get some battery or
generator-driven aeration. See my section on what to do during power outages. Most fish that die from hurricanes die due to
lack of oxygen due to a lot of low oxygen rain and power outages preventing aeration.
- Clear away large debris from in and around the pond.
- Locate and account for the pond animals and plants. Upright plants, remove dead animals,
retrieve fish, and so forth.
- Check the pond's pH and hardness and adjust them if needed. If the pond water is
discolored, or chemicals were washed into the water, add a mesh bag of activated carbon to the
filter (assuming you have main or backup power) to help remove those.
Here is a link to a thread in my forum about Hurricane Rita in 2005:
Recovery After Storms
I follow a routine when it is snowing. This is what I do after the snow is done. If I am home, and
it is daytime, and it is not too bad outside, I will do these things while it is still snowing as
- I put on knee boots for shallow snow and my hip waders for deeper snow.
- I walk to each pond in turn. First, I clear away the snow near where the de-icers are. If there
is a lot of snow, the de-icer and opening in the pond may vanish. Getting air to the fish comes
first. I will wear gloves or aquatic gloves and then dig like a dog in the snow with my hands.
Sometimes, I will use a plastic container or bucket to pitch the snow instead.
- After clearing where the pond opening is, I will clear off the electrical equipment. This
means the top of the air pump so oxygen can get in there and all the electrical outlets to keep
water out of the outlets. It is important to do this before the snow melts and re-freezes as ice
which cannot be removed.
- For my big pond, I clear the snow off of the top of the waterfall and biofilter. In the winter, I
cover the top of the biofilter with a Rubbermaid tub lid and weight that down with diver's lead
weights. I now put the de-icer into the top of the open biofilter, floating there. With the
Rubbermaid lid suspended on top of that, it keeps the wind and snow off of the de-icer so it
continues to function properly.
- If the snow is really deep, that is all I can really do at first. Normally, snow is shallow, and I
continue with clearing snow around the stream and off the pond net if there are nets still out on
the pond. I keep a net on the deep end of my big pond year round now to keep off the herons.
The snow will collapse the net so I have to get the snow weight off of it. I also clear the edge of
the net which I have to lift up to get into the pond before that ices up. That way, I can get in and
clean the filter sooner
- In the cases where I need to get into the pond, and the net is frozen down, I can use a hair
dryer to try to get up the net. Sometimes I poured hot water but that usually freezes and makes
things worse. I use the hot water to pour down the waterfall and melt some ice and openings. In
frustration, a few times, I just have torn the frozen net to get into the pond. It was much easier
before having the net on in winter!! If you do not have heron problems, do not use the net in
winter. I have only done that since about 2004 when the herons came.
See my pond winterizing page for more on ponds in the winter.
Read my pond newsletters for stories of my daily struggles
with the ponds all year.