Many people with pets justify the use of regular nasty plastic grocery bags with cleaning up their pets' poop.
But have you heard of biodegradable poop bags? If you've got to throw away poop from pets, it's a great solution.
Here's another idea- while not as perfect as the idea above, it's a way to reuse something that would otherwise be thrown out anyway: Why not use another readily available bag? ...Sure, if you're trying to be more green, you're choosing items with less packaging and waste. But let's face it- some items will come in a bag and there is nothing you can do about it. Bread, chips, a lot of crackers and cookies... these all usually come in a sealed bag. You can re-use this bag for picking up after the pets instead.
For a cat's litterbox, some recommend flushing. However, if you leave near a coastal area or near rivers or other water sources, it's best not to flush it. Sea otters are being infected with a toxin that could be coming from the flushed cat poop and litter. The best solution is, again, a biodegradable plastic bag.
Before reading further, keep in mind:
Do NOT use cat or dog poop in compost that will be going on or anywhere near your vegetable garden!!!
Their poo contains toxins that you don't want coming near anything you eat. Eewwwww.
You can compost your cat's poop and litter remnants:
If you are interested in composting your dog's doody for gardens without vegetables, here's an article about how you can: