global warming
air pollution
mercury toxicity in groundwater
mercury in seafood
nuclear waste disposal
organic farming vs. pesticide farming
genetic engineering (and risk of environmental contamination)
smog
toxic emissions by recreational videos in state parks
misuse of public lands in National Forrests
overharvesting the oceans for seafood
deadzones in the Gulf of Mexico from fertilizer run-off
pharmaceutical residues in the public water supply
wetlands destruction in Florida and other states
water shortages in California and the west coast
draining water tables and aquafers in Texas and other dry states
ozone layer destruction
new automobile environmental technologies (fuel cell, hybrids)
invasion of zebra mussels in public waterways
sustainable forrest issues
That is a short list but should give you ample things to choose from
Enjoy