Chloride is a serious threat to Missouri's freshwater lakes and streams. Chloride does not break down or settle out of water, so prevention is the only solution. As a result, our lakes and streams are getting saltier. At elevated levels, salt—specifically the chloride part of salt, or sodium chloride—is toxic to fish and other aquatic life. One teaspoon of salt pollutes five gallons of water. 

Chloride occurs naturally in lakes and streams, and many organisms need it to carry out the basic functions of life. But elevated levels can cause cells to lose water and become deprived of nutrients, ultimately killing fish, amphibians, plants and other aquatic organisms. On land, excessive amounts of chloride can harm pets, soil, cars, bridges and more.

Although scientists have known about the potential for chloride to cause problems in the environment since at least the 1960s, it wasn't until recently that researchers began to learn the true extent of the problem.

How Chloride Pollution Affects Our Lives

  • Drinking water — In some areas of the state, salt has contaminated groundwater, affecting its taste and healthfulness.
  • Fish and aquatic organisms — At low levels, chloride can negatively affect aquatic life structure, diversity and productivity. High amounts of chloride are toxic to fish, aquatic organisms and amphibians.
  • Plants — Chloride in streams, lakes and wetlands harms aquatic vegetation and can change the plant community structure. Salt can also kill plants and trees along the roadside. 
  • Soil — Salt-laden soil loses its ability to retain water and store nutrients and is more prone to erosion and sediment runoff.
  • Pets — Salt can sicken pets that eat it, lick it off their paws or drink salty snow melt/runoff. It can also irritate their paws.
  • Wildlife — Some birds, like finches and house sparrows, can die from ingesting deicing salt. 
  • Infrastructure — Chloride corrodes road surfaces and bridges and damages reinforcing rods, increasing maintenance and repair costs.
  • Agriculture - Chloride also gets into the environment through fertilizer use, livestock waste, dust suppressants, industries and other inputs. 

What You Can Do to Fight Chloride Pollution

When clearing snow from walks

  • Apply a liquid deicer before it snows to prevent snow and ice build up.
  • Shovel, snow blow, plow and sweep early and often. The more snow and ice removed, the less salt needed.
  • Less is better. A coffee mug full of salt is adequate for a 20-foot driveway or 10 sidewalk squares. If leftover crystals are visible, the salt has been over-applied. 
  • Use a handheld spreader that applies salt consistently.
  • Wait for warmer weather. When ground temperatures are below 15 degrees F, it’s too cold for ordinary sodium chloride to work. At those temperatures, it's better to use sand.
  • Use the right deicer. Calcium chloride works at much lower temperatures than sodium chloride.
  • Sweep up extra salt. If it is visible on dry pavement, it is not doing anything and could be washed into water.

When considering, choosing or using a water softener

  • Find out the hardness of your water by calling the city, consulting a professional or using a hardness testing kit. If water is at an acceptable level, think twice about softening. The chloride standard for drinking water is 250 mg/l.
  • Check your unit’s settings. It may have been set at an unnecessarily high level at the factory.
  • Soften only the water that needs it, not outside spigots or cold drinking water taps.
  • Monitor your softener. If it uses more than one bag of salt per month, work with a water quality professional to optimize efficiency.
  • Look into lower-salt methods. Pre-filters can be used to remove iron, manganese and hydrogen sulfide without help from water softeners.
  • Upgrade your softener. Look for demand-initiated versions that are more salt efficient, operate based on how much water you use and can reduce salt use by up to 60%.
  • If you have a timer-based system, see if you can extend the time between cycles.

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