It’s all the rage: Let’s ban plastic bags once and for all, for the environment. Several local news outlets began reporting last week on a new online petition pushing for such a ban. The petition, begun by Green Philly Blog, was even signed by City Councilman Jim Kenney, who back in 2009 unsuccessfully co-sponsored a citywide plastic-bag ban himself—originally just a fee, actually, but that was deemed anti-poor.

On its face, sure, this is a good idea. After all, throughout the country, plastic bags create 300,000 tons of landfill waste annually, according to the NRDC and cited by Green Philly Blog in the article that accompanies the currently 402 signatures for a ban. The average U.S. family uses 1,500 plastic bags per year. That’s a lot of petroleum-based waste.

Bans have gone into effect all over the country. The biggest city to ban bags is Los Angeles. Seattle’s ban was made official on July 1, 2012. A similar ban exists in Portland, Oregon. And Pennsylvania State Sen. Daylin Leach unsuccessfully attempted a statewide fee here a last year.

And as with most pressing issues of the day, there are vehement arguments on both sides of this debate. The plastics industry, obviously, hates this and successfully lobbied against the Philly tax/ban proposal in 2009. Among some of the statistics they no doubt deployed to get 10 councilmembers on board: Plastic bags make up less than one percent of space in landfills. Some cities that have banned plastic bags have additionally instituted small fees on paper bags—but doesn’t taxing any sort of bag create a burden on the poor? Additionally, many studies show that the paper alternative may actually be worse for the environment. Producing paper bags takes more water and energy, and more space in trucks to transport. Once discarded, paper bags take up more space in landfills than plastic bags. (Not to mention that a ban on a single recyclable product sort of overlooks the very real long-term solution of recycling. And considering the implications of the single-product ban, please note it takes more energy to recycle paper than plastic.)

Those reusable bags? Often made in China and shipped here using cheap, dirty fuel. Studies show only 10 percent of customers remember to take their reusable stores to the store on a regular basis, even in places where plastic bags have been banned. Then they biodegrade slower than plastic bags—and are piling up as more companies trendily hand them out with your clothing order.

But my additional, personal problem with a plastic-bag ban is really, really specific: Someone needs to clean up all the dog shit. And if I know people—and I do know some—they’re not going to travel through hell and high water, a.k.a. Manayunk, to buy plastic bags for poop-scooping if they don’t have free ones laying around. That means more shit all over the streets.

I’m not just worried about stepping in it. I’m worried about drinking it.

According to the Philadelphia Water Department, dog waste in yards and parks is a source of storm-water runoff pollution. Why? Because we live in the goddamn Delaware River Watershed. According to 2004 statistics compiled by Merritt Clifton, editor of Animal People News, there were 325,271 dogs living throughout the city of Philadelphia. Philly produces about 90 tons of dog poop per year, according to Joanne Dahme of the Philadelphia Water Department. Nationwide, 40 percent of all households own dogs, who produce 3.6 billion pounds of waste each year, equaling—and I’m only telling you this because I love you—800 football fields of animal poop, stacked a foot high. The average dog takes a dump 20 times a week, which means 20 plastic bags a week.

Okay, so what? Well, just as it does on land, animal waste acts as a fertilizer in the water, meaning it promotes plant growth—which can choke waterways, increase algae blooms and rob the water of oxygen, according to phillywatersheds.org. Not to mention that the bacteria that grows in poop can cause disease. Dog waste can additionally contain Toxocariasis, a roundworm that can be transmitted from dogs to humans which causes vision loss, fever, and a cough, among other terrible side effects. The PWD has actually enacted programs over the last few years to combat dog waste’s impact on our water supply—and help spread the word to those who don’t know any better.

But if we ban plastic bags, it sort of won’t matter if we know any better or not. Some people, currently on the verge of caring, will stop. I live in a relatively clean neighborhood, and there’s still dog shit all over the place. Buying separate bags just for dogs? Some people might do that—but I don’t need a study to tell me that some people won’t.