Urine Luck!

I strongly suspect that this question may be some type of prank, but our motto here in the basement, "Per Omnia Respondea," calls on me to treat your query with respect. Urine is not the human effluent with which we need be overly concerned. Of all your choices, peeing next to the road is the one I would dis-recommend -- particularly if it is dark, as you might be hit by a passing motorist. Urine is very high in nitrogen and, although relatively clean, can potentially carry pathogens; for that reason, it is best to avoid peeing into storm drains that lead directly to bodies of water, or even to sewage-treatment plants. Similarly, if you have a well, don't pee on top of it, and don't pee into rivers and streams. Peeing in your garden (particularly onto the compost pile) or in the woods is fairly innocuous. The soil, if healthy, will filter out the nutrients it can use and eventually break down whatever bacteria might be present.

In terms of snakes and wildlife, use the same judgment that would guide you in any non-peeing outdoor situation. I have not heard a single anecdote about snakebites during woodland evacuation. Do be very cautious of certain poisonous plants -- poison oak, poison ivy, even nettles -- about which peeing horror stories abound. You know what they say, "Take nothing but memories, leave nothing but footprints." Poison ivy is not a pleasant memory, but it can stay with you for weeks after an unlucky sylvan sojourn.

Haunchily,
Umbra