Natural landscapes, natural foods, natural fibers – natural should be a good thing. But "natural" is not always good, as anyone who's dealt with a natural disaster will tell you. Erosion is a natural process and has created some amazing landscapes on the planet, but on a smaller scale such as a slope near a sidewalk or house, it's not something you want. If you have open land on your property, you need to control for erosion. You can't stop the basic process of water washing soil away, but you can modify the ground so that the soil doesn't go anywhere. If you don't, you end up with much more than a mess. 

Impassable Sidewalks and Shoulders

Soil flowing onto a sidewalk or road shoulder makes that area impassable, which is bad for people in wheelchairs and who have other mobility issues. You might not have a problem walking on mud, but that does not mean others just have to deal with the mud, too. Plus, that mud can be slippery, and that's a slip-and-fall lawsuit waiting to happen. If nothing else, for your insurance policy's sake, you've got to control the erosion on that slope.

Unstable and Uneven Ground

Erosion creates uneven ground that's harder to walk on, and the ground can even become unstable if erosion has undercut a section. That can lead to damage as edges of parking lots become unstable and unusable, for example. You increase the risk of tripping and falling, too, and structures that are constructed nearby may need to be relocated or torn down.

Exposed Utility Lines

Utility lines are not buried just below the surface of the ground, but in some cases, they can be as close as 18 inches below. Serious erosion that isn't addressed can eventually expose parts of the utility lines. And if the erosion has reached that point, then you're likely looking at unstable soil surrounding the lines, too, which could mean having to shore up the lines' stability. By controlling erosion, you could avoid all that future work.

Dead Landscaping

One of the reasons you see so many plantings along slopes beside roads is because the roots of those plants help hold soil in place and fight against erosion. However, if the slope erodes and there is landscaping at the top of the slope, the roots of those plants become exposed. When they're not surrounded by soil, they can't absorb nutrients and water from the soil, and that kills the landscaping.

Erosion control takes several forms. Have an environmental engineering or landscaping company look at the area, and they'll be able to tell you which options would be best.