The poop is also a health issue, especially in those quantities. Rats feed off it too. And its not like we need more of those.

Motion detector ultra-sonic dog repellent to keep them out of your yard.
http://www.safehomeproducts.com/shp2/product/koolatron-outdoor-cat-and-dog-repeller-with-ac-adapter/electronic-pest-control/159684/159684.aspx

leave a note on the dog

I think the best way is to post a sign in your yard with a picture of a dog shitting and a no symbol over it.

Is there a neighborhood listserv? You can post there and try shaming.

I would start with a letter to your own block. Make it anon. who cares. Just point out politely the district has scoop and leash laws.

If you can identify the dog and owner, I am sure a fine can be mailed to them. This is true in some suburbs. I am not positive about D.C., but I would think it would be a great way for them to collect fines! Bonus points for photo.

I understand this is likely to be the wrong crowd for this request, but here goes. I'm in a central neighborhood with high dog density and inconsiderate owners really cause problems.

When the weather heats up, my whole neighborhood smells faintly of shit because among the many dog owners/walkers, enough of them won't scoop that we have piles of crap... I'd say at least every 20 feet or so... on the sidewalk or in tree wells.

And then there's the leash issue. We're not usually talking dogs that seem aggressive, but even so they get into everyone's personal space, whether we like dogs or not. As you can guess, I... do not. I feel like I shouldn't have to touch them, because owners have an obligation to keep their animals from becoming a nuisance.

And THEN, most of those who do use leashes use expanding leashes or very looooong leashes that create kind of a trip wire effect for other pedestrians on the narrows sidewalks.

I just think this is not cool. Most of the offenders are either quite young-- the busy professionals who get dogs instead of having children, or quite old-- the faded hippies who comprised the first wave of gentrifiers here in the '70s and '80s. Frankly, I find both groups incredibly self-centered in general. Figures that they can't be bothered to curb or clean up after their animals.

Is there any way to get bad owners to take responsibility for their dogs in public places?