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Water: Educator Resources

How is the quality of our waters determined?

Every state adopts goals or standards that need to be met for its waters, based on the intended uses of the waterbodies. Different goals are set for different waterbody uses. For example, if the water is going to be used for cooling machinery in a factory, it doesn't have to be as clean as water used for drinking. Scientists monitor the waters and give them one of the following scores:

(GOOD) The waterbody fully supports its intended uses.

(IMPAIRED) The waterbody does not support one or more of its intended uses.

What is the quality of our waters?

Surface waters are waters that you can see. These waters include rivers and streams, lakes, ponds, reservoirs, wetlands, coastal waters, and estuaries. For the U.S. waterbodies sampled most recently, about 40% are rated as impaired. The charts here show, by the type of waterbody, what percentage of the assessed waters were rated GOOD and what percentage were rated IMPAIRED.

How many uses for water can you think of?

Make a list of how water is used by people, plants and animals. Here are a few ideas: drinkstamp

  • drinking
  • swimstamp
  • swimmimg
  • showering
  • watering the lawn
  • homes for fish, bugs and wildlife
  • irrigating crops
  • heronstamp
  • navigation
Scientists group these uses into a few overall categories, like Aquatic Life, Drinking Water, and Recreation. They then decide what categories of uses a waterbody should support (for example, virtually all waterbodies should support aquatic life), and monitor the waterbody to see if it supports its uses.
What percentage of all waterbodies are assessed?
We don't have the money or technology to sample all the waterbodies in the U.S. The nation has more than 3,600,000 miles of rivers and streams alone! If all the rivers and streams were placed end-to-end, they could wrap around the earth 144 times. Each state assesses only a portion of its waters, Here are the lates numbers we have for percentage of U.S. waters assessed:
  • 19% of rivers and streams
  • 43% of lakes, ponds, and reserviors
  • 36% of estuaries
  • 6% of ocean shorelines
  • 92% of Great Lakes shoreline

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