Horse and Mule Manure in National Parks: Keeping Trails Clean and Water Safe

Image from the National Park Service's page

Pack animals haul supplies to remote corners of national parks and carry visitors to and from their destinations — improving the visit and bringing supplies where people would otherwise go without. But with horses and mules comes manure. People are asked to leave no trace; the same goes for stock. Concessioners who run pack and riding operations are responsible for limiting their animals' impact, and should follow the Leave No Trace principles for stock.

On the trail and in camp

• In the backcountry, scatter, rake and disperse manure off the trail where possible. Hikers and cyclists share the trails, and nobody wants to step in or ride through it.
• At trailheads and busy spots, clear manure from the trail as soon as possible. Clearing it also aerates it, which keeps flies and larvae away and lowers the risk of polluting waterways.
• Manure within about a quarter mile of a trailhead or stable is often hauled back to the stable — but concessioners should check their operating plan for where removal is required.
• Near camp, disperse manure piles daily.

Properly dispersed, horse manure is unlikely to spread disease to people; harmful bacteria such as E. coli in it are killed by sunlight.

What manure does to the land

Equine manure contains nitrogen, phosphorus and carbon. Managed well, those nutrients make good fertilizer. Managed badly, they reach groundwater and streams through runoff or by leaching from piles, and ammonia reaching surface water can trigger excess algae, harming the waterway.

Caring for the stock

• Feed weed-free hay, a key part of the standards stock are evaluated against. Hay with weed seeds spreads invasive noxious weeds through manure; these crowd out native plants, increase erosion and reduce biodiversity, and are hard to control.
• Use eco-friendly fly protection. A University of Minnesota study found reusable leggings with ingredients such as citronella worked best, keeping animals clean, comfortable and less exposed to disease.

Composting

Horses and mules produce 30 to 70 pounds of waste a day. Composting turns it, through heat, chemistry and beneficial bacteria, into rich soil cheaply and cleanly:

• Put the pile close to corrals and stables for easy hauling.
• Keep it from getting too wet, which slows composting and causes odor as microbes run short of oxygen.
• Make sure drainage doesn't reach any stream, river or other water.

Concessioners should look for local partners — community composting programs and farms — to use the compost as fertilizer on fields and pastures, or as potting soil, mulch and yard fertilizer.

More: NPS on invasive plants, and EPA on reducing methane from livestock manure.

Sources

Based on "Equine Manure Management and Environmental Impacts," National Park Service; a work of the United States government in the public domain.