Bikes and Horses

You should know that the section in question is only 12’ wide and has deep culverts that drop off quickly on both sides – so any sort of separate of uses is out of the question.

A:  If the trail is paved and has a grassy shoulder, usually asking equestrians to stay on the grass alleviates the poop problem. But it sounds like the trail tread may be stone dust (you mentioned divots).  Divots are worse (deeper) when horses are ridden at speed. You could try posting a sign that limits equestrians to walking only (but that would be such a shame, as rail trails are a favorite place to go faster - good footing, and usually a straight stretch of trail).  A compromise would be "Walk and trot (or jog) only" as cantering, the horse's third gear, causes more and deeper divots than trotting or walking.

Consider asking equestrians to stay to the extreme right side of the trail, leaving the center of the path unmarred by divots. I know you said the trail has a drop off, is there any kind of barrier along the edge? Providing even a visual barrier such as railroad ties along the edge (as opposed to a physical one, a sturdy fence) can provide some comfort and guidance to an equestrian trail user going along the edge.. Unfortunately it is a natural tendency for everyone to "aim for the middle", but merely making the suggestion may help! Horses that are driven have little choice but to go down the middle (or the cart would capsize over the edge). But most rail-trails see more equestrian riders than drivers.

Posting a sign at the trailhead, or signs along the stretch that is open to horses, which says "Please clean up after your horse" may or may not get results. Many people ride tall horses, and find it difficult to mount and dismount when on the trail. Some riders ride because they have physical disabilities, and cannot dismount easily. So they are unlikely to dismount to kick the manure off the trail. The answer to that problem is to separate the parking areas that are used by equestrians and cyclists/pedestrians.

Manure from one or two horses per day on the trail usually isn't a problem. Upwards of ten horses per day gets to be a bit much. Horses produce about 50 lbs of manure per 24-hour day, but from experience I know most of this lands in the barn and trailer where I have to clean it up. The rest is usually deposited at the beginning of a ride (Horses are nervous in their new surroundings, and exercise causes them to "unload"). So you're likely to see more manure at or near the trailhead than farther on down the line. Is it possible to create an equestrian-only parking area, separated from the bike/ped parking area? If it were located 5 or more miles from the bike/ped area, less pedestrians are likely to get that far and encounter the problem.

Finally you can try to put a positive spin on horse manure! It is all natural, recycled material that provides sustenance for various other species (bugs, birds, worms, mice ...)! It also breaks down fairly quickly in the sun, usually leaving no more residue than your lawn mower's clods of wet grass clippings. Educational signage at the trailhead may help pedestrians get over the 'Ew!" factor. My friend Dr. Cyla Allison has an excellent presentation on manure, perhaps you could borrow from it.