Across
- 7. a system of supplying water to dry land
- 9. growing or living naturally in a certain country
- 11. a person actively involved in conservation
- 12. a wall built to keep back water
Down
- 1. waste water
- 2. the wearing away of topsoil by wind and water
- 3. the dying out of species
- 4. a chemical substance used to kill weeds
- 5. all the different types of plants and animals
- 6. illegal hunting
- 8. thrown away after being used
- 10. a substance which causes pollution