Winter Season Waterways Information

Aquatic Habitats in Winter
A Salty Situation: Road Salt Effects on Waterways

Nitrates on the Rise in Winter

Winter Safety when Sampling

Salt & Sand in Winter Waterways

Aquatic Habitats in Winter

by Chad Cochrane and Sarah Falkowski From January 15,2000 newsletter During the winter, aquatic organisms face the challenge of adjusting to temperatures low enough to freeze their homes.  To deal with this,organisms have come up with a number of different strategies to survive. These range from remaining active to slowing down their activity to sleeping through the winter.

As temperatures fall outside, life present in and around streams and ponds takes a dramatic turn. Water in the pond freezes over, enclosing and protecting animals that sleep through the winter nestled in mud and those that remain active.  In the slower moving pools of streams,ice forms over the top of the water.  However, ice may never form over the more rapid riffles.  When this happens, the life within the creek must prepare for a long winter spent at a body temperature of only4 degrees Celsius.  Although many organisms die, they leave behind eggs and seeds as their method of survival.  Duckweed, for example,deposits tiny green scales during the winter months.  As springs rolls around, the scales surface and grow.

Fish and other cold-blooded animals adjust their body temperature to the environment they live in.  They are fast and nimble in the summer because the water temperature is about room temperature, but in the winter they slow down as their body temperatures drop.  Some fish – such as the trout, salmon, pike and yellow perch – are specially designed to deal with this.  Even at low temperatures, their bodies allow them to swim easily.  They often take refuge in the deepest part of the stream were the water is warmest.  Other fish, such as bass, sunfish,and catfish must hibernate (pass the winter in a resting state) due to their inability to cope with the cold water.  They move to the edges of the stream or pond and bury themselves in mud or leaves.  There they wait until they can successfully swim again.  Bullhead catfish can often become completely frozen during the winter, thaw in spring, and live without harm.  This is an amazing adaptation to the winter season!

Fish are not the only creatures living in the streams during the winter. Insects also have adaptations to survive the winter. Many invertebrates burrow in the mud or leaves for the winter.  Spending their time as eggs, larvae, pupae, or adults, insects often secrete a fluid that is similar to antifreeze in order to withstand the cold. Huddled masses of water boatmen and backswimmers can sometimes be seen in small air pockets under the ice. When the occasional early spring thaw melts the surface ice, water striders and diving beetles swim in the near freezing water.  Dragonflies and damselflies perform a similar task, but in the larval stage.  Aquatic sowbugs are also active.  Many water fleas display rounded heads in winter, when the water is cold, and pointed heads in summer, during periods of warmth. (The pointed head is thought to be an adaptation to increased predation in the summer.) Horsehair worms have a unique solution to the problem of winter temperatures.  They choose to either hibernate among shore plants or to remain in the host body and parasitize.

Snails become very inactive in winter.  Those present in water that freezes solid, burrow into mud and plant debris to hibernate. Some water mites may temporarily do this as well.  Mussels become dormant (inactive), too.  This is evident from the darker rest rings on their shells, sometimes called “growth rings.”  Mussels do not grow during the winter, yet they are sometimes seen active through clear ice.  Crayfish remain active, but not as active as they are in the summer.  They tend to burrow into wet meadows and banks.  Leeches become dormant and bury themselves in mud or plant debris.  Adult newts and mud puppies remain active, while salamanders hibernate under logs and stones.  Most frogs hibernate in the mud below the ice, though some survive the winter in their tadpole stage.  Many turtles also burrow into the mud and become inactive during the colder months. Snapping turtles, on the other hand, settle beneath plant debris and logs or even stay in muskrat or beaver burrows.  Both snapping and painted turtles become active sometimes, and can be seen crawling around under the ice.

Mammals also overwinter in the frozen streams.  Beavers make large mud and wood lodges that they stay in when the pond behind the dam freezes. Beavers keep their food underwater for the winter and have thick layers of fat and a dense coat of fur to protect them from the cold water. The actual living area inside the lodge is above the water line so that they stay warm and dry when not swimming.  In fact, steam can sometimes be seen rising from beaver lodges on cold days.  Otters and muskrats also stay for the cold weather.  Though muskrats would rather stay under the ice like the beaver, otters love the snow.  They have been observed making paths on the snow banks and sliding on their bellies into the water.

Most aquatic plants die in autumn to prepare for winter.  However,they only die back to their roots, which means that they can grow back when the weather gets warmer. Plants that are partially submerged either wholly or partly disintegrate during the winter. Algae on the other hand,remain photosynthetic all winter long, or survive as spores in a dormant state.

Along the water’s edge, chlorophyll is being broken down from the leaves of deciduous trees and shrubs during the winter months.  This is why the leaves change colors in the fall- they are dying.  Before these leaves drop from the limbs, though, they sprout winter buds that carry embryonic leaves and flowers through the period of winter dormancy. Although deciduous trees don’t grow during the winter, conifers do perform photosynthesis when the temperature rises above freezing.

Mallard ducks stay near ponds as long as there is some open water. They can swim in cold water and stand on ice because they have thick feather insulation and their feet are adapted to keep out the cold.  In contrast,many other species of birds migrate when the weather begins to chill. A few kinds of butterflies do as well.  Cold-blooded toads, water snakes, and garter snakes head under decaying logs, in stone piles, burrows,or other holes, and hibernate.  Raccoons only become active on mild days, on cold ones they hibernate in their dens.  A raccoon’s hibernation sleep accompanies near normal body temperature with only slightly slowed circulation and respiration rates.  Deer change their diet for the winter.  They eat tree buds, twigs, bark, and conifer foliage. Moose do the same, with the addition of aquatic plants as well.

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A Salty Situation: Road Salt Effects On Waterways

Researched by: Katie Howlett, Dhira Dale
Written by: Dhira Dale  From January 2001 Newsletter It’s that time of the year again when the snow is falling… and falling and falling and falling.  Despite how nice it looks on tree branches or rolled up into a snowman, if snow is left unattended on the roads it can cause problems.  So what has man done to remedy this situation?  That’s right!  Snow plows and salt!  The yummy salt (NaCl) that goes on your mashed potatoes also goes on the roads to melt the ice and snow for safe traveling.  According to the PA Dept. of Transportation, each year Pennsylvania uses approximately  90,000 tons of salt (mostly NaCl) to de-ice the 40,500 miles of highways and roads (Kundman, 1998).  Now the question is, how does this extra salt affect our waterways?

Many roadways drainage systems empty rain, melting snow, and slush directly into nearby waterways through pipes, culverts, and ditches without treatment.  Storm drains do not always connect to a municipal treatment facility.   In addition, salt gets mixed in with the snow on the roads and then finds its way to the nearby soil through plowing, runoff, and cars splashing it onto the berms.  So the salt from roadways can enter streams directly from the road or from surrounding melting snow (runoff) and groundwater.

The salt then gets dissolved by the water and becomes part of the Total Dissolved Solids of the creek.  Total Dissolved Solids (TDS) are minerals, organic matter, and nutrients that have dissolved in the water.  Consequentially, salt from the roads increases the TDS of a waterway.  Specifically it raises its salinity.  Salinity only deals with salts and is defined as the concentration of all ionic constituents that includes, halides, bicarbonates, and sodium chloride (NaCl).   Large bodies of water, such as rivers may not feel the effects of road salt.  TDS readings tend to decrease in the winter months due to heightened water discharge.  Small streams and creeks are the places where the amount of TDS from salt may jump a considerable amount.

A sudden or extreme change in TDS and salinity can be harmful to aquatic life.  Aquatic organisms require a certain amount of TDS in the water.  If the amount of TDS is too great it will affect an organism’s ability to regulate the amount of fluids in and out of its cells.  This process is called osmosis.  If the ionic concentrations in the water become greater than the fluids within the organism, the creature will lose body fluids and dehydrate.  So putting your happy little goldfish into the salty ocean will cause it to have to spend more energy on controlling its osmotic regulation, adding much more stress to its life.   In some studies, adult freshwater fish have been found to tolerate TDS concentrations up to 10,000 mg/L (Sorensen et. al, 1996), much higher than you probably have found in your creek, and some insects such as net-spinning caddisflies may not affected by higher salinity (Kundman, 1998).  Other studies do suggest that pollution such as salinity can cause insects to drift, let go of the creek bottom, enter the water column, and float
downstream to more favorable conditions.  Nevertheless, it is hard to determine how spikes in stream salinity concentrations can have an affect on aquatic life behaviorally or physiologically.

– Kundman, J. M., 1998.  The Effects of Road Salt Runoff (NaCl) on Caddisfly Drift in Mill Run, Meadville, PA.   Meadville, PA:
Allegheny College.
– Sorensen, D.L., V. Mortenson, and R. L. Zollinger, 1996.  A Review and Synthesis of the Impacts of Road Salting on Water Quality.
Salt Lake City: Utah Dept. of Transportation UT-95.08.

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Nitrates On the Rise in Winter

From Nov. 10 and Dec. 10, 1998 newsletters. You might start noticing something with your nitrate test results as we enter the winter season – they might increase.   Nitrates (converted from nitrogen) is a nutrient needed by living organisms for protein development and DNA / RNA synthesis, and it is naturally present in our aquatic systems.  The levels of nitrates can fluctuate seasonally from both natural and human influences, as shown by Graph 1.     Note an increase in this level begins in November.

Why is this happening?    What are some of the natural causes for this increase that happens in all streams?  Think about what is happening out there in the environment during this time of year that would add nutrients to soil and streams.   What might be some of the human influences for the change?

Nitrates (a form of nitrogen in water) are needed by all living plants and animals to help build proteins, DNA, and RNA.   From soil,plants retrieve nitrates with their roots; animals obtain nitrates by eating plants directly or indirectly.  Eventually, all the accumulated nitrates in an organism are returned to the soil through excretion (waste production)or by dying and decomposing.  This is a simplified version of the nitrogen cycle.

The winter rise…There are a number of reasons why nitrate levels increase during the winter.   Bethel Park High School knew that decaying leaves and dead terrestrial (land)  and aquatic plants were adding nitrates.  Because vegetation is dormant (not growing) during this season means that the roots are not taking up nutrients.   Instead they can be washed into the stream by rain and snow melts, especially off of bare agricultural fields.

Meadville High School  knew what causes the slight rise in the summer – increased use of agricultural and lawn fertilizers.  This can also be an input all year round. They also knew that sewage can be added to a stream any day.  This includes malfunctioning septic systems outside of homes and failing municipal sewage plants.  Any outdated plants that treat both sewage and storm runoff cannot handle high volumes of water after snow melts and storms.   So it is sometimes sent into the waterway only partially treated.    In addition to human sewage, animal waste from pastures is another nitrates input. Ever see a cow standing in a stream?  Plop, plop.

But aren’t nutrients needed in a stream?  Yes, but too much can disrupt the normal aquatic environment.  More nutrients in the water would encourage excessive algal and plant growth.  Green soupy water could appear.  Even though plants produce oxygen, needed by the creatures living in the water, there is still a problem.  Eventually the algae dies.   When plants die, the process of decomposition (bacteria at work here) sucks up the oxygen – taking it away from the fish, insects,and mussels living in the water.   Bethel Park knew all about this problem called eutrophication.. Meadville High School pointed out that if this occurs, you would only find organisms that are poor water quality indicators (Group 3 that can tolerate low oxygen levels or pollution).  Another good point was made concerning the disruption of the aquatic food webs if algae is overabundant.   Adding more herbivores (vegetarians)might bring things out of balance.

Nitrates in drinking water may also be a health risk to humans, especially babies.   Therefore, the EPA sets a limit of 10 ppm of nitrate for public drinking water.   So keep an eye on your and other school’s nitrate levels and see if there is any increase during the winter.

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Winter Safety when Sampling

We do expect you to do some sampling in the winter – on safer days with no blizzard and maybe slightly warmer weather.   Please emphasize safety to your students since it is cold out and the water is cold.   No one should enter the water without proper hip waders/chest waders, and even then you might want to be prepared for someone getting wet. Have a blanket and/or extra change of clothes.  It might be a good idea just to stay out of the water completely until spring.   Make sure students watch for slippery stream banks and be cautious of leaning into the stream to get a sample (we do have milk jugs on a stick to retrieve samples more safely).  If sampling from a bridge, make sure no one stands on top of piles of plowed snow when bailing.  We don’t want any students falling into the creek to get the sample.

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Salt & Sand in Winter Waterways

by Lindsay Herendeen

From December 5, 2003 Newsletter

Winter has arrived, and with winter comes slippery sidewalks and icy roads.

To battle these conditions, the Pennsylvania Department of Transportation applies chemical de-icing agents and abrasives to roads throughout the state. During the months of November through January, the roads of Pennsylvania, like most in the Northeast and Midwest, receive large doses of salt and sand combinations. Together, salt and sand help to melt snow and provide traction. However, a large percentage of these products end up in streams, rivers and lakes as a result of runoff, plowing, and splash from motor vehicles. In return, these chemicals and abrasives have negative effects on water quality. Each year, local and state governments spend millions of dollars on water clean up from road salt.

Salt is applied to roads to speed up the process of melting snow. Most road salt is applied just before or during the beginning stages of snowfall because it dissolves in the water and lowers water’s melting point so that snow melts faster than it accumulates.

Since salt has a high solubility, it dissolves readily in water and is easily transported with runoff, contaminating surface water and groundwater. As salt levels increase in a body of water, total dissolved solids also increase. If total dissolved solids become too high, aquatic life has trouble executing basic life processes such as respiration and photosynthesis. High salinity in groundwater can also contaminate drinking water and water used for irrigation; that can have potential negative human health impacts. Salt-laden runoff can even damage riparian (stream-side) vegetation, inhibiting its ability to buffer the waterway against the salt inputs.

Sand is used as an abrasive to help motor vehicles get traction on slippery or icy road surfaces. Pennsylvania uses some form of sand or stone to fulfill this purpose. Although sand is beneficial for traction, it does little to get snow off the road and must be combined with salt or other chemicals to be effective.

Since sand and stone do not dissolve in water, they are transported with runoff as snow begins to melt. If too much sand is applied to the roads, it can clog the drainage systems that would normally transport the sediment rich runoff to sewage treatment plants. Instead, the sediment enters the nearest creek or waterway. In large amounts, sand can increase turbidity, making life processes difficult for macro-invertebrates by clogging their gills. Sediment buildup can also disrupt habitats by filling cracks and crevasses. To make matters worse, sand can absorb and transport oil and other pollutants into waterways. Sand-clogged drainage systems can even lead to flooding.

De-icing agents are not beneficial to the environment, but are necessary for safe transportation in the winter months. The future of de-icing looks promising as state departments of transportation research techniques for de-icing in a more environmentally friendly way. For example, calcium magnesium acetate is being evaluated to replace salt because it melts snow as efficiently but with fewer consequences on water quality. The Salt Use Improvement Team at the University of Michigan recommends magnesium chloride as a salt and sand alternative. These and other more eco-friendly products are slightly more expensive than conventional de-icers but this cost is outweighed by the important ecosystem functions that they protect. Many states are also creating stricter requirements regarding the storage of road salt and sand in attempt to prevent disastrous leaks. Other preventative measures being taken by departments of transportation include natural snow fences along open stretches of highway like the one planted by Maplewood High School last year, and pre-treatment of roads before snow piles up.

For now, states in the Northeast and Midwest, including Pennsylvania, must continue to battle the economic effects of salt and sand on the environment.

Winter is here and streams may begin to freeze over, but water quality issues are still prevalent.


PennDOT: Pennsylvania Department of Transportation. <> (1 Dec. 2003).
Pennsylvania Department of Environmental Protection. <> (24 Nov. 2003).
Road Management Journal. <> (24 Nov. 2003).
USGS Water Resources. <> (24 Nov. 2003).
Hodel, Lindsay. “Safer De-icing Chemicals.” Mother Earth News December/January 2004: 56-57.

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