Environmental science puzzle

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Across
  1. 4. Method of extracting oil or natural gas
  2. 5. Reduction in dissolved oxygen from a certain point
  3. 6. Most effective way of pollution control
  4. 12. lakes with low nutrient levels, clear waters
  5. 13. Method of cleaning rivers via waste consuming bacteria
  6. 15. Addition of nutrients to a water source
Down
  1. 1. Eutrophication due to human activities
  2. 2. Rapid increase in algae due to eutrophication
  3. 3. areas of water where aquatic life can't live due to low oxygen
  4. 7. Process of treating water, removing color, smell, and killing most bacterias
  5. 8. dumps a small city worth of pollution
  6. 9. Decreasing concentration by adding water
  7. 10. Water used at home or through industrial practices
  8. 11. Most significant oil spills in the world
  9. 14. lakes that have lost too much oxygen and aquatic life begins to die off