In the News

Ski Area Erosion
date posted: December 16 2003

By John Cobourn, Water Resource Specialist;
Heather Segale, Environmental Education Coordinator; University of Nevada Cooperative Extension

Skiing represents much that is good about the outdoors: clean air, tall forests, incredible views, and lots of fun. But some other things that are completely out of the view of the skiing public also affect water quality, fish habitat, and even water quantity. These are impacts of construction and maintenance of ski runs and other resort infrastructure. The land management practices that allow us to enjoy the outdoors so much in the winter can turn into an environmental liability the rest of the year.

How do we know the impacts or our practices? Direct measurement of water quality shows that ski area drainage can deliver nutrients and sediments into the streams of our watershed. But, it’s not the same for all ski areas, and it even varies within individual ski areas. The big question is what to do about it. Erosion control best management practices (BMPs) have been used for years, but we are now realizing that some are more effective than others are.

As a former ski area erosion control manager, Michael Hogan, Integrated Environment Restoration Service, understands how difficult it is to get information about what works and what doesn’t. He recently worked with ski area managers and Sierra Business Council to form a team of ski area personnel, erosion control specialists and representatives of the Lahontan Regional Water Quality Control Board to help understand and improve ski area BMP effectiveness. The program uses a scientific approach, employing techniques on the ground in the form of test plots, and then quantitatively measuring the results. In this way, speculation is minimized and effectiveness is maximized. The group working on these issues, known as the California Alpine Resorts Environmental Cooperative, is developing “guiding principles” for approaching any erosion control project, as well as a set of technical notes on BMPs.

While the ski area guiding principles have not yet been released, Hogan and his group already have some tips that will be helpful in many different situations where we need to control erosion on slopes, even in our backyards.

Hogan and other researchers have studied native mountain soils for years. When undisturbed by humans or vehicles, they are usually noncompacted and have organic matter mixed well below the surface. They are loose soils with a duff layer of decomposing needles or leaves on the surface, and they can absorb great amounts of rainfall like a damp sponge. For effective erosion control, we need to have soils with characteristics much like those of native mountain soil.

Proper soil preparation before planting is the key to success in stabilizing slopes. The combination of good soil and healthy plants will generally prevent runoff and erosion. When plants become established, they create an extensive root system, a microbial community and a physical structure that is sponge-like. To build such a sponge:
1. Include adequate soil organic matter such as good compost, wood or bark chips.
2. Till the organic matter into the soil to a depth of 6 inches to 12 inches, and then be careful not to compact the soil with vehicles or foot traffic.
3. Choose the appropriate plant material. Ski slopes are generally seeded with native grass species that require no irrigation or fertilization once established.
4. Top off the soil/plant community with a generous layer of mulch, such as pine needles, wood chips or bark chips. Mulch is spread on top of the soil to protect it from raindrop impact, to prevent the bare soil surface from becoming sealed, and to provide a very slow release of plant nutrients into the soil.

There are many benefits to creating this kind of natural erosion control. It is self-sustaining once established. The health of the soil is maintained by the growth of plants and an adequate layer of mulch. Porous soils promote infiltration of moisture deep into the ground, where it is available for tree roots. This prevents rapid runoff of sediment-laden water to streams. Instead, the water is filtered as it moves slowly downslope through the soil to the local aquifer and eventually to the stream or lake.

As erosion control professionals continue to share the results of their research, ski areas and other property owners will be able to incorporate their findings to help restore the natural functions of the Lake Tahoe watershed. That process will take years, but most resource managers agree that the effort will be necessary to protect the beauty of Lake Tahoe for future generations. So if you have a chance to ski Tahoe this winter, be sure to take a moment to consider the work being done to control erosion at our ski areas, appreciate the beauty and fragility of our mountain environment.

For more information, contact Hogan, Integrated Environmental Restoration Services, Inc., (530) 525-1335.

Watch for “The Lake Tahoe Report” in the North Lake Bonanza each Friday, and tune in to KOLO-TV News Channel 8 Tuesdays at 5 p.m. to learn more. In next week’s article, learn how the residents of one Tahoe neighborhood have challenged themselves to complete implementation of their home best management practices by the time their local EIP project is finished. “The Lake Tahoe Report” is a collaborative effort of the Lake Tahoe Environmental Education Coalition, University of Nevada Cooperative Extension, UC Davis and the USDA Forest Service. For more information, contact Heather Segale, University of Nevada Cooperative Extension, (775) 832-4138, or logon to www.lteec.org or www.unce.unr.edu.