Frequently Asked Questions
What are riparian areas?
Riparian areas are the zones along rivers, streams and lakes that form the interface between land and water. The word riparian is derived from the Latin word "ripa" meaning riverbank.
Why are riparian zones so important?
They comprise a small portion of total land area, but are more diverse in terms of plant and animal life than upland areas. Seventy-five percent of all Montana plant and animal species depend on riparian areas. The plants in riparian areas also stabilize riverbanks, filter out pollution that storm water collects as it flows through urban or agricultural areas, and shade the water—keeping it cooler for trout and other aquatic life.
How do riparian areas protect property?
Rivers and streams are dynamic systems. Flow amounts vary greatly from season-to-season and year-to-year, and river paths change over time. The land and plants along rivers and streams act like sponges, slowing and absorbing excess flows during times of high water and floods, and then slowly releasing water over a period of time. These areas also allow river channels to migrate over time, as they naturally do, without threatening property.
When native vegetation is cleared, or when roads and buildings are constructed in these areas, less "sponge" is available. Pavement and building foundations cannot absorb water like vegetated land can. Peaks of flow during high water and floods become more severe, and water moves faster than it would if riparian areas and floodplains were left in their natural state. This means more flood damage over a broader area.
When people place "riprap" (most commonly large rocks) or build retaining walls to prevent streams from migrating and eroding their property, the erosive force of the river is increased and channeled directly at the next downstream bank. This process, often spreading from one property to the next, makes the problem worse and worse for downstream neighbors.
The best solution is to leave native vegetation in place, and build or pave as far back from the stream as possible. A distance of 75 to 300 feet from the riverbank is usually recommended. The ideal distance may be longer or shorter, depending on the size of the river or stream, and the lay of the land.
What can I do to help protect these areas?
If you live near a river or stream, leave the native vegetation in place. If vegetation already has been cleared, plant native tree and shrub species appropriate to the location.
Lawns are not a good choice for streamside plantings. Lawns do not provide the bank stabilization, filtering of pollution, wildlife habitat and shade that native trees and shrubs do. Also, many fertilizers and herbicides applied to lawns easily run off and pollute the stream or lake. County Weed District and Extension Offices have information on fertilizers and herbicides that are registered for use near streams, if weed control is required.
Many local nurseries carry native riparian species and can provide advice on what, where and how to plant. County Extension Offices also have information on planting native species.
How do I know if water quality is being degraded?
The signs of degradation vary dramatically. Without testing, there's no way to be sure how clean or unclean water is. Still, common symptoms of pollution include aggressive algae growth, heavy sedimentation, slimy rocks, scum in eddies and backwater areas, and reduced diversity of aquatic life.
What is a safe distance from the bank for siting a home?
This depends on your site and on the river. But generally, the farther your building is from the river, the better it is for water quality. On large rivers, a 300-foot setback isn't too far. Your goal should be to stay out of the floodplain and the riparian corridor. Also, be sure to site your septic tank and drain field according to all regulations and maintain it properly to reduce pollution from sewage.
Are native plants available from local nurseries?
Yes. And many are easy to establish. Common varieties for our area include: redosier dogwood, serviceberry, snowberry, golden currant, Woods' rose, water birch, mountain alder, Rocky Mountain maple and Douglas hawthorn. Willows and cottonwoods can be purchased as "bare-root" stock in the spring.
How should I treat weed infestations along waterways?
Treating noxious weeds can be important for the health of riparian areas, but it can also be tricky along waterways. We recommend that you contact your local weed district or county extension office for information.