Watery Doing?

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Across
  1. 3. Naturally occurring liquid or frozen H2O containing no salt
  2. 5. Describes salty water
  3. 9. Make something impure by exposure to a pollutant
  4. 10. A repeated process or cycle of improvement
  5. 11. Necessary for life
  6. 12. The introduction of harmful materials into the environment
Down
  1. 1. A body of porous rock or sediment saturated with groundwater
  2. 2. Useful tools for monitoring water resources
  3. 4. When mountains block rainfall needed for plant growth it has this effect
  4. 6. A chemical that repels or kills pests, such as insects
  5. 7. A device used to remove something unwanted from a liquid or gas
  6. 8. Synthetically cause rainfall by putting chemicals into the atmosphere