A riparian area is the green area next to rivers, creeks, streams, lakes and wetlands where water strongly influences the vegetation (Fig. 1).

The vegetation, in turn, influences the water. Riparian vegetation stabilizes stream banks and reduces erosion. Stream bank vegetation can improve water quality by filtering sediment and capturing excess nutrients in runoff from upland regions. Stream bank vegetation provides shelter for birds and small animals. Overhanging vegetation cools streams for fish and provides debris and organic matter, food for insects and other life in the water.

 The Environmental Protection Agency states that agriculture, particularly animal keeping, has a greater impact on river contamination than any other nonpoint source. Nonpoint source contamination includes such things as silt and nutrients that do not come from pipes, or point discharges. Nonpoint sources of contamination can, when added together, create significant water pollution.

Grazing, particularly improper grazing of riparian areas in the arid west may contribute to nonpoint source pollution by removing the vegetation that prevents some stream bank erosion.

Eroding stream banks, regardless of cause, can fill in downstream wetlands, ponds and lakes as well as waterways, drainage ditches and irrigation canals. In the process, silt can clog fish spawning beds and interfere with recreational uses.

Removing stream bank vegetation also can allow stream channels to cut deeper until they abandon the flood plain. The deeper channel carries water through the riparian area without sustaining the vegetation. This results in a less productive riparian area and an increased flood hazard downstream. The pattern resembles damage from erratic flows, like floods, caused by lack of infiltration in the upper reaches of the watershed. The process is widespread throughout the West.

Waterborne pathogens, and bacteria from manure can transmit livestock diseases such as bovine leptospirosis and mastitis. Fecal pathogens can injure shellfish beds, limit recreational uses and cause a significant health hazard. The amount of contamination depends upon the frequency and timing of grazing, number of animals with access to the stream and the hydrological regime of the watershed. Bacteria can survive for long periods in stream sediments and may keep bacterial levels in water high.

Nutrients in manure may naturally enrich the stream and downstream water bodies. Manure contains high levels of phosphate and nitrogen. Phosphate is the limiting nutrient for growth of most freshwater plants. One pound of excess phosphate may promote the growth of about 100 pounds of algae. Algal blooms make the water murky, preventing light from reaching plants at the bottom of the lake. When aquatic plants die, bacteria in the lake digest the dead plants, using up the oxygen in the water. Without sufficient oxygen, fish and other aquatic animals die. More bacteria consume more oxygen and the lake dies. The name of this process is eutrophication. Excess nitrogen causes the same effect in marine waters.

The Coastal Zone Management Act Reauthorization Amendments (CZMA) became law on November 5, 1990. The CZMA affects most of western Washington. Other legislation affects eastern Washington waters. Under the CZMA, states are to develop coastal nonpoint source management programs by July 1995. These programs must conform with guidelines developed by the Environmental Protection Agency, such as the Grazing Management Measure. The Grazing Management Measure is designed to protect sensitive areas including riparian zones. According to David Davis, deputy director of EPA's Office of Wetlands, Oceans and Watersheds, the measure designates the following practices for sensitive grazing areas:

• exclusion of livestock,
• providing crossings and access for stock drinking,
• providing alternative drinking water locations,
• locating salt and additional shade, if needed, away from sensitive areas, and
• using improved grazing management.

One alternative to grazing riparian areas is to keep livestock away from the riparian area. Livestock managers should consider permanently excluding livestock from riparian areas that have poor recovery potential or when there is no practical way to protect the riparian areas while grazing adjacent uplands. Green vegetation, cool temperatures and water are all lures to livestock.

Herding, salting, developing alternative water sources, and placing drift fencing and exclosures can keep livestock away from riparian areas. In degraded riparian pastures, livestock exclusion can improve and protect water quality by encouraging regrowth of the vegetative cover. Healthy native vegetation, in turn, stabilizes the stream bank and prevents erosion. Improved stream bank vegetation provides habitat for wildlife and fish.

Fencing can develop additional pastures, giving the manager more control over grazing. Better grazing control can improve pastures. Water development—improving stream access or installing water tanks—often improves livestock health and performance.

Fencing to exclude livestock is expensive. Installing and maintaining an electric fence costs up to $1,000 per mile. A three-strand barbed wire fence is about $1,500 to $2,500 per mile. Fencing both stream banks doubles the cost per mile. Interest expenses to borrow the money and opportunity costs of foregoing other improvements also add to the cost.

Fencing some stream banks is impractical.

• Steep banks may preclude fencing.
• Floods may wash out fences in some areas each spring.
• Fencing above high water levels may exclude too much forage.
• Fencing the entire riparian area may prevent access to other management units.
• Building and maintaining crossings can cause frequent fence damage.
• Ranchers need to provide water access for livestock.

Off-Stream Water Sources

Providing water sources away from the stream reduces animal time in the stream and lessens impact on water quality. Sources may include troughs fed by wells, or springs, or water piped from the stream.

Direct deposition of manure into the stream is the principal factor affecting bacterial water quality. The only exception is during rare overland flow events when rainfall or snow melt exceeds the infiltration capacity of the soil.

In an Oregon State University study, Miner and others reported that 8 days of winter observations showed that cattle in a pasture having both a water tank and stream access spent an average of 1.6 minutes per cow per day in the stream. Cattle with only the stream as a water source spent 25.6 minutes per cow per day in the stream. The tank was on level ground and the ground was dry. The animals may have preferred the water tank because it was warmer, or they may have chosen the ease of access over the steep, rough, muddy streamside.

Water Developments

Set water tanks on level, dry ground with unrestricted animal access. Size the water tanks to provide adequate watering for the herd. Use tank heaters to keep the tanks from freezing in the winter. Tank heaters need a power source.

Water for the tanks can come from wells or from the stream. Electricity, generators, windmills, or solar panels can power pumps. Electric pumps need to be self priming and must have a cutoff to prevent overfilling the tank. Gas pumps are usually hand started.

Another type of pump is a hydraulic ram that uses the stream's own power or topographic gradient to pump water to a tank. If the gradient to the stream is sufficient, divert or pipe water directly to the tank. If overfilling is unavoidable, provide a drain system to prevent creating a mud hole.

Improved in-stream watering

If no alternative to using the stream as a water source is practical, improving access can protect the stream bank and water quality. A fenced water lane is possible, but fences across streams tend to catch debris, wash out, or sustain other damage that requires extra maintenance. Creating a graded, cobbled or paved access area is often feasible. Livestock prefer the easiest access.

Attracting Livestock away from Riparian Areas

Feed livestock away from the riparian area when livestock require supplemental feeding. Providing salt blocks away from the riparian zone also attracts livestock away from streams. Livestock, however, will move to riparian areas when not provided with alternative watering sites.

Riparian areas also provide shade in many pastures. Animals may need alternative shade on hot days. After all, on a hot day, what better place is there to loiter than beside a tree with your feet in the water? Providing shade or scratching posts and dusters will reduce riparian loitering. Culling individual loiterers often reduces herd use of riparian zones. Loitering is a learned behavior.

Grazing Strategies that Protect Riparian Areas When There Is No Fence

Even when using fencing, livestock managers may want to take advantage of the forage available in the riparian pasture.

Strategies for timing grazing in an unfenced pasture apply just as well to grazing a fenced riparian area.

Give emphasis to "controlling the timing of grazing: (a) to keep livestock off stream banks when they are most vulnerable to damage; and (b) to coincide with the physiological needs of the plant species," according to Cheney and others, reporting in a USGPO publication, Livestock Grazing on Western Riparian Areas. Adding more rest to the grazing cycle increases plant vigor, allows stream banks to heal, and encourages more desirable plant species. Managers should limit grazing intensity to a level that will maintain desired species composition and vigor.

The vegetation in the riparian area and the steepness of the stream bank suggest the following grazing strategies.

Meandering Streams, Lakes and Wetlands with Trees and Shrubs

Trees such as willow, alder and other brushy species cannot tolerate summer grazing. Frequent browsing depletes food reserves, killing older plants. Dormant seeds in the soil germinate, but browsing and trampling eliminate the seedlings. Trees and shrubs eventually give way to weeds and less desirable vegetation.

Graze riparian areas with brushy banks in the winter when the brush has no leaves and shoots have hardened. The grassy understory, not the brush, will attract livestock grazing. Leave enough understory vegetation, 4 to 6 inches, to protect banks between trees and brush from spring runoff, state Clary and Webster in Riparian Grazing Guidelines for the Intermountain Region. In the Intermountain region, this corresponds to a utilization rate of 30% to 40%, Cheney reports.

Again, when supplementing livestock feed, move away from the stream and provide alternate water sources. Windbreaks or other shelter also can attract livestock away from the riparian area where they may be loafing or seeking shelter from wind. Remember, manure deposited inside the high water mark during the winter will likely wash downstream in the spring. Bacteria in manure may remain viable for at least one grazing season. Nutrients remain even longer.

Approach summer grazing cautiously. If conditions require summer grazing, trees and shrubs may need 2 to 3 years of rest to recover. If possible, avoid grazing during peak roosting periods for riparian bird species.

Meandering Streams, Lakes and Wetlands without Shrubs

Meandering streams, lakes and wetlands that have grass banks and no shrubs lend themselves to two grazing strategies. The basis of both systems is having at least 6 inches of residue available to catch sediments during spring runoff events.

First, allow short-term grazing in the riparian area. Remove livestock when they have grazed the vegetation down to the desired level. Livestock may use the riparian area more than once each season if the forage recovers. Carefully monitor fall grazing because little or no regrowth will occur before spring runoff.

Second, if grazing for longer periods when the forage will have less than 6 inches remaining, remove the grazing pressure in time to allow the vegetation to regrow to at least 6 inches during the remainder of the growing season. Remove the livestock earlier as the elevation increases. Suggested utilization rates are about 50%, according to Cheney.

Streams with Steep Gradients

Some streams are swift moving and have steep banks. Stream banks are vulnerable to erosion by swiftly moving water, particularly during spring runoff. The vegetation in these areas needs plenty of time to recover after grazing and before the spring runoff. Grazing may occur in the spring. This leaves all summer and fall for vegetation to recover.

Vegetation stubble should be 6 inches, preferably 12 inches the next spring.

Grazing pressure will be lighter in the spring. Cold air flows downhill into the riparian area and livestock will not linger. They will move out of the riparian area to higher, warmer areas to feed. Cattle will not eat the trees until mid-summer, so trees and brush will be relatively unharmed.

Bluegrasses in Forested Areas

Along forested riparian areas, sometimes bluegrass (Poa pratensis) will dominate. Bluegrass is a rhizomatous grass, spreading by roots. Graze these areas hard, leaving 2 to 3 inches of grass. This will encourage the growth and spreading of the bluegrass. These areas need time to regrow, however, so do not graze from mid-summer through fall. Note that this recommendation excludes the return of desirable native species, and grazing "hard" in meadows may compact soil and reduce water infiltration.

Make a Grazing Plan

Riparian areas need precise management plans and close monitoring to protect the water resource. Studies throughout the West have demonstrated the value of protecting the riparian area and allowing degraded areas to recover.

• Vegetation improves,
• water quality improves,
• stream banks recover,
• water quantity improves, and
• water tables rise, providing more water retention and longer stream flows.

Cost Sharing and Other Resources

For help in designing riparian pasture management systems, contact your local Cooperative Extension, Soil Conservation Service or Conservation District offices (Table 1). Financial assistance may be available from your local Agricultural Stabilization and Conservation Service office. Volunteers sometimes are willing to help build and maintain riparian fences. Contact your local sporting associations, environmental groups or civic organizations. They may be willing to pitch in to protect or improve downstream community water resources. Adjoining landowners may share the job or be a problem. Involve them!

Stream Corridor Improvement

Deferred Grazing

Fencing

Livestock Exclusion

Proper Grazing Use

Proper Woodland Grazing

Streambank Protection

Stream Channel Stabilization

Troughs and Tanks

Wetland Development or Restoration

Davis, D. 1993. EPA Discusses Control of Nonpoint Sources with Board of National Cattleman's Association. Nonpoint Source News-Notes, May 1993: 12-14.

Miner, et al. Evaluation of Off-Stream Water Source to Reduce Impact of Winter Fed Range Cattle on Stream Water Quality. State of Washington Water Research Center Report 78:65-73.

Cheney et al. Livestock Grazing on Western Riparian Areas. 1990. U.S. Government Printing Office: 1990-775-443/21, 661, Region No. 8

Clary, W.P. and Webster, B.F. 1990. Riparian Grazing Guidelines for the Intermountain Region. Rangelands 12(4): 209-211.

Partial funding for this publication was provided by the Washington State Department of Ecology and the U.S. Environmental Protection Agency through CWA 319 Water Quality Grants.

By Edward B. Adams, Ph.D., Washington State University Cooperative Extension

Eastern Washington Water Quality Coordinator, WSU Spokane.

Issued by Washington State University Cooperative Extension and the U. S. Department of Agriculture in furtherance of the Acts of May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, color, gender, national origin, religion, age, disability, and sexual orientation. Evidence of noncompliance may be reported through your local Cooperative Extension office. Published March 1994. Subject codes 375, 120 A