What would you say to a product that is advertised as the best solvent in the world? This incredible liquid consists of small polarized molecules that can dissolve anything! The solvent is powerful enough to cut through miles of rock as well as your everyday grime. Would you want a bottle of this stuff? You already have it. It is water -- H2O.

So, what does the solvent and corrosive water have to do with trails? You already intuitively know the answer. You probably have ridden on such deeply rutted trails that your horse interfered and nicked the inside of his hind fetlocks. After all, water was responsible for the Grand Canyon, and is the force that moved Niagara Falls seven miles upstream from its original location.

You may have wondered why some trails remain so smooth while others develop those detestable ruts. Maybe you blamed bicycles or overuse. Maybe you tried to solve the problem by taking a line parallel to one side of the rut -- which eventually just created another rut. But somewhere deep down, you knew this was the result of erosion caused by water running down the trail rather than across the trail. The trails that remain smooth and flat are really flat -- they don't go up or down a slope. Water runs across those trails.

When water runs down the trail rather than across, we say the trail is following the fall line. Professor Gene Wood of Clemson University defines the fall line as "the shortest slope distance over which free-flowing water will maximize its change in elevation as it moves down a slope."

Once upon a time, the Colorado River went down the fall line from Colorado to the Gulf of California. That rut you are riding could one day be the next Grand Canyon.

Nobody likes to ride in deep ruts, so what is the solution? Those ruts are always going downhill -- no matter how gradual the slope; if it's rutted, it's downhill. We humans are so smart that we always calculate the shortest distance to our destination, just like water. And straight downhill is shorter and quicker than back and forth across the hill to the bottom. So, we usually ride straight down the hill; down the fall line.

This eventually creates the ruts which are so problematic. The solution is: Don't ride on the fall line! Sure, it's more trouble to reroute the trail that you are used to, but it pays off. The payoff is less erosion for your trail, less risk to your horse and more miles for your workout.

Reroutes can be a lot of work. You have to find a new route which never descends or rises more than 50% of the slope (50% rule: on grades nearing 50%, erosion cannot be controlled). You may have to cut brush and cut in a trail tread.

Rerouting is a lot like washing the dishes or going to the gym. You dread it, avoid it, and find all sorts of excuses not to do it today. But when you finally get started, it's not as bad as you thought. And when you are finished, you feel seriously proud.

Plan on developing only short segments at a time, i.e., less than a quarter-mile at a time. Like any potentially onerous task, break it into doable segments.

So, how do you choose the reroute? You have to think like water. (It should be easy since 80% of your brain actually is water.) Water depends on gravity to find the most direct route down the slope -- the path of least resistance.

The more time water spends on the trail, the more time its physically corrosive and solvent properties have to do their work on the trail tread. You want to choose a reroute that minimizes the amount of time water spends on your trail.

Think like water. Help the water get down the hill by routing the water over your trail rather than down it. This happens when the slope of your trail never exceeds 50% of the slope of the hill you are traversing.

In most areas, you are well advised to keep the grade pitch of your trail around 10% of the slope of the hill. You also help the water get down the hill by outsloping your trail tread so that water can easily flow across it.

To build such a trail, you need to know how to estimate the slope of the hill and the trail. Slope is estimated by the number of feet of vertical rise or fall per 100 feet of horizontal distance, expressed as a percentage. So, a drop of ten feet per 100 feet of trail is a 10% slope. If the hill rises 30 feet per 100 feet horizontal distance, its slope is 30%. In this case, you would not want your trail to exceed 15 feet (50% of 30 feet) per 100 feet of horizontal distance.

As water flows downhill, even with a minimal trail grade, it increases in velocity and, thus, in the erosion it causes to your trail. You minimize this damage by creating wide-sweeping turns every 30 yards or so. A wide-sweeping turn is larger than a switchback in that you can't see one leg of the turn from the other.

When your trail crosses a gully or other natural drainage on the fall line, you make your trail more durable by laying it out so that it curves away from the direction of water flow. This is called a grade reversal. It is built by laying your trail uphill around or through the gully rather than straight down through the gully.

On an eroded trail, you may be tempted to attempt to block water running down your trail with a log, rocks or other obstruction. This is called a water bar. It may sound good in theory, but it rarely works well and will require a lot of maintenance. Water bars often produce a muddy mess on the uphill side. A better solution is to reroute your trail.

This discussion started with a focus on the corrosive effects of water and how we all dislike riding ruts in our trails. This is a brief synopsis of some of the practical information available in an AERC Trail Master class.

Our trails are one of three essential elements of our sport and represent our national heritage. If we want to keep riding and protect our heritage for our children, we must protect our trails. The take-home messages: (1) Think like water, and (2) Don't ride the fall line!

P.S. Any time you work on trails, log in your hours on the Trails section of the AERC website. Thanks.

New members: join online by clicking here or phone the office toll-free, 866-271-2372.

Renewing? Click here, or give the office staff a call at 866-271-2372.

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