Photo Credit:DNRC Photo Library. The house pictured above would have been safe from flooding had it been located further away from the river, or possibly if the banks were protected with dense plants, shrubs or trees.
What is a Riparian Area
The land bordering streams, rivers, wetlands, ponds, and lakes are unique ecosystems called riparian areas. Riparian areas are transitional zones that exist between a body of water and the surrounding drier upland. These areas occupy only a small part of the total watershed area, 2%-4% of Montana's land base, yet they play a substantial role in regulating many hydrologic processes. Riparian areas act as buffers, moderating flow, temperature, and the amount of nutrients and sediment transported to the water from the surrounding landscape. As such, their influence extends well beyond the small area they occupy, providing numerous social, economic, and ecological benefits. To truely protect Montana's surface water, we need to understand the benefits these areas provide and why they are important to protect.
Services of Riparian Areas
Governments, communities, and individuals spend millions of dollars building infrastructure to replicate natural processes of riparian areas. Below are some of the important services that intact and properly functioning riparian areas provide free of charge.
Montana's 175,000 miles of streams and rivers are all vulnerable to flooding. Riparian areas allow flood waters to spread out horizontally past the channel, providing temporary water detention and storage. The vegetation, debris, and porous soils of riparian areas absorb flood waters, as they slowly return to the main channel. This action can reduce the force, height, speed, and volume of floodwaters. Flood control by riparian areas can mitigate damage to downstream urban, suburban, agricultural lands, and irrigation structures.
Moderate Water Temperature:
Riparian vegetation can help moderate water temperature fluctuations and extremes. The riparian canopy of streams and rivers reduces the amount of solar radiation reaching the water's surface, allowing the water to remain a stable cool temperature. Increaed temperatures decrease the oxygen-carrying capacity of streams and increase the rate at which nutrients become available to aquatic life. Montana's 85 species of fish depend on stable temperature regimes; 26 of these fish are considered game fish, important to fishing and the economy.
Riparian vegetation protects the land against accelerated erosion rates by dissipating water energy. A deep, binding root mass holds soil in place, stabilizes stream banks and prevents excessive loss of adjacent soils. Stream banks that lack these deep roots are unstable and erode easily.
The riparian area essentially acts as a filter or sink, reducing the input of nutrients and sediment to surface waters from the surrounding watershed. Riparian vegetation physically traps nutrients, and the sediment to which they are attached, as it is transported via overland flow. The diverse vegetation of a ripairan area can trap 80% to 90% of sediments transported by fields. Nutrient input to the stream is further reduced by the uptake of dissolved nutrients by plant roots in the shallow subsurface zone. It was found that riparian forests retained more than 65% of the nitrogen and 30% of the phosphorus contributed through overland and subsurface flow from surrounding agruicultural lands. Furthermore, a study done in Maryland demonstrated that riparian areas removed more than three-quarters of the dissolved nitrate transported from croplands.
Riparian areas provide habitat for wildlife, including migratory birds, mammals, reptiles, and insects. Food and water for wildlife are provided by these areas; dense vegetation serves as a high forage area, while the canopy acts as a windbreak and thermal cover; and large woody debris that enters streams and rivers created instream habitat for fish, invertebrates, and other aquatic organisms. Riparian areas are an important breading ground for birds. In western Montana, 59% of bird species breed in riparian habitats and 35% of these only breed in riparian habitats. Corridors that connect other habitats and facilitate movement of wildlife are formed by riparian areas.
Naturally vegetated riparian areas and wetlands enhance groundwater recharge by holding water long enough to allow it to percolate into the underlying soil. This helps maintain surface flows in rivers and streams and is vital to support late summer stream flows.
Protecting Riparian Areas has Payoffs!
Riparian areas are part of what makes Montana such and attractive place to live, work, visit, and play!
Properly functioning riparian areas provide clean water by filtering the pollutant load in runoff and restricting sediment from entering the stream or river. Clean water is important in Montana for recreation, drinking, washing, and irrigating.
Riparian areas maintain water storage and availability, increase vegetation, reduce stream bank erosion, enhance forage quantity and quality, and provide shelter for livestock.
Increases Property Value and Marketability:
Private property values can benefit from the protection of wetlands, ponds, streams, and rivers. People value the amenities that greenway corridors provide; and research indicates that people are willing to pay 6% or more for property near protected riparian areas. Riparian vegetation enhances the beauty of the land and the stream while offering homeowners privacy from anglers and boaters. What's more, properly functioning riparian areas can provide resistance to noxious weeds like leafy spurge, spooted knapweed, and common tansy.
Tourism and Recreation:
If you enjoy hunting, fishing, canoeing, bird watching, or hiking, you probably owe intact riparian areas appreciation. Montanans spent more thatn $678 million on such activities in 1995, adding to the local economies through travel, equipment, outfitting services, food, and lodging. Montana's booming recreation industry depends on healthy streams and rivers and therefore the adjacent riparian areas.
Ensuring a healthy stream and riparian area protects out land, our water, aquatic life, and downstream neighbors. How do you know if you have a healthy riparian area and stream? Check the following characteristics for indicators.
Unhealthy Riparian Areas
- Eroding or undercut stream banks
- Barren stream banks
- Poor water quality
- Water murky with suspended sediments
- Abundance of noxious weeds and non-natives
- Lack of vegetative diversity
- Absence of shade-providing trees
- No wood debris
- Upland vegetation growing next to the stream
- High water temperature
- Limited diversity of aquatic life
- Dry stream banks
Healthy Riparian Areas
- Stable banks anchored by vegetation
- No excessive erosion
- Shaded, clear and cool water
- Channel contains leaves and woody debris
- Dense, diverse vegetation
- Diverse wildlife
- Stream banks are saturated or moist
Best Management Practices to Protect Your Riparian Areas, Streams, and Assests
These ecologically sensitive and beneficial areas are increasingly threatened by developmental pressures of expanding urban, residential, and agricultural areas. Human activities such as building construction, livestock grazing, and landscaping can harm riparian areas. Best management practices (BMPS) are strategies to prevent or minimize the harmful effects of human-related activities on riparian resources, functions, and values.
BMPs to Help Stream and Yourself
- Keep riparian vegetation intact.
- Limit building in riparian areas.
- Leave no soil bare! Plant native grasses, hedges, shrubs, and trees.
- Let plants grow, and avoid mowing within 10 to 25 feet from the edge of a stream or creek.
- Eradicate noxious weeds. They cannot anchor stream banks as effectively as diverse native plants, and riparian areas serve as corridors for dispersal of invasive species.
- Maintain natural woody debris in riparian areas. It can dissipate erosive energy and act as a nursery for aquatic life.
- Size culverts properly to accommodate passage of extreme flows and debris and avoid ponded conditions. Use debris screens at the inlet and inspect often.
- Avoid applying pesticides, herbicides, and chemical fertilizers near the riparian area.
- Build bridges long and high enough to accommodate floods.
- Locate buildings away from riparian areas. Depending on the stream, a safe distance might by 50 feet or 100 feet. If the building is located next to a larger river it might be several hundred feet. Many Montana counties, cities, and subdivisions have regulations governing minimum distances between new buildings and rivers, wetlands, and streams. Contact your city or county planning offices.
Grazing and Riparian Areas
of the 93 million acres in Montana, about 56 million are in agricultural production; 18 million acres are in cropland and 38 million acres are in pasture and range. Farming and ranching are and integral part of Montana's history, economy, and cultural heritage. Consequently, recognition of the challenges they pose is imperative to keeping riparian areas healthy and intact.
Common Impacts of Unmanaged Grazing in Riparian Areas
- Trampling by livestock can change channel shape and flow
- Loss of anchoring vegetation
- Destabilizing stream banks
- Pathogens and nutrients from cattle excrements deposited in water
- Accelerates erosion and increases sediment load to water
It is important to maintain farming and ranching productivity while seeking to minimize negative impacts to our waterways. Complete and permanent exclusion of livestock from lush, high forage riparian areas is one option that has not been widely adopted; particularly because it is costly in terms of materials, maintenance, and loss of productive forage. Presenting farmers and ranchers with more feasible options for protecting streams, while protecting their agricultural productivity, will make taking action to preserve waterways more attractive.
The negative impacts of livestock grazing in riparian areas can be prevented, minimized, or improved by controlling when, where, how long, and with what intensity livestock graze the forages in the riparian area. The BMPs listed below can help promote livestock health and productivity, and protect riparian areas that safeguard water quality and quantity.
Avoid grazing in riparian areas during rainy season.
- Limit livestock time in pastures with riparian areas.
- Develop off-stream water in locations where adequate forage is available on upland sites.
- Rest riparian pastures during the critical growth period of plants that provide stream bank stability.
- Leave enough plant growth to protect stream banks and filter sediments and relocate to the next grazing unit.
- Provide adequate regrowth time and rest for plants.
- Set grazing periods and specific rest periods to protect stream bank stability.
- Alternate the season of use from year to year.
Downloadable form of this webpage (Best Management Practices in the Riparian Zone)