November-December 2007

Natural System Functions and Restoration

Thirty years of change at Bear Creek

Tweet

Much effort has been expended in the past dealing with directing stormwater into concentrated flows and then directing those flows into safe locations. There is, however, another approach to managing water that relies not on artificial structures but on maintaining a healthy ecological system. A healthy, well-functioning water catchment (a much more descriptive term than watershed) will filter sediment, buffer high flows, and most importantly keep water on the land longer. Healthy water catchments not only reduce floods and ease droughts on their own but also prolong the useful life of dams and reservoirs by reducing the volume of sediment (which can shorten the life of a reservoir by filling it in) and reducing the need for maintenance of facilities. In addition, because a healthy water catchment has the ability to intercept storm pulses and slowly release the water in more even and well-distributed flows, the size and expense of engineered stormwater structures can be significantly reduced if the catchment is functioning properly.

Critical to creating and maintaining healthy water catchments is recognition of the resilient and dynamic balance between soil, water, and vegetation throughout, but especially in riparian areas. Fortunately, humans have been observing and studying streams and water catchments for a long time, so the physical processes within water catchments are relatively well understood. The key is to manage so those physical processes are in a working order. The social aspects of creating and maintaining healthy water catchments are somewhat more complex. Humans have not always taken care of natural water systems to the best advantage. Ignorance, greed, and apathy have all played a role in creating less-than-ideal conditions along many of the world’s water systems. Fortunately, it is possible to change the way the land is treated, and the land will respond accordingly. But to make such changes, people must be willing to cooperate with each other and believe that they can make a positive difference.

August 1986

Riparian restoration and management has been a major issue in the arid West since the mid-1970s. Early restoration efforts were mainly the responsibility of wildlife and fisheries biologists and concentrated on the exclusion of livestock for habitat improvement. Through experience and research it is now known that the restoration of riparian areas affects much more than just wildlife and fisheries habitat. The condition of riparian areas influences water quality, aquifer recharge, sediment filtering, energy dissipation, runoff timing, late-season stream flows, the rate and volume of erosion, and streambank stability. This is accomplished through what is often referred to as stream function, or the interaction of water, vegetation, soil, and landform. A stream is functioning properly when the stream morphology (shape), hydrology, and vegetation are able to dissipate the energy of normal high flows without excessive erosion, sediment transport, or channel adjustments. This is accomplished by a combination of dissipating energy within the stream channel and the floodplain.

Energy dissipation can be accomplished with large rocks and land form. But more often than not, vegetation is the linchpin to creating a dynamically stable and resilient stream channel and water catchment. This is especially true in areas of fine sediment.

An ideal riparian vegetative community will have sufficient numbers and varieties of vigorous plants of appropriate species to stabilize the soil with their roots and protect the soil surface by dissipating the energies of high flows. Vegetation is often superior to rock for stabilizing a stream channel as it is able to adjust and fill in when there is a change in the stream channel. It not only helps protect soil surfaces, but it can help build and stabilize stream channels as well, by capturing and retaining sediment during high flows.

June 1987

Given the history of manipulating water catchments, streams, and riparian areas, one might ask why it has taken so long to begin to understand these important processes and the consequences of those actions. One reason is that people were, and still are, driven by their values and opinions, and, as someone once said, “Everyone is right from their point of view.” Another reason was not having a common language (terms and definitions) with which to communicate ideas so others could understand. There are many more reasons, but these two became large stumbling blocks toward progress. Recognition is now growing that to produce the values people desire from streams and associated riparian areas on a sustainable basis, these systems must be functioning to a certain level. Only when the basic physical attributes and processes are present and operable in streams and riparian areas are the desired values produced. When this is not the case, it is akin to using up the capital in the system and not producing any interest. The problem is not new. Plato wrote about water running off denuded hillsides into poor-condition streams in 400 BC. He said that water was no longer stored in the ground to be released as springs and streams but instead ran quickly back to the ocean. He also said that “the shrines of extinct water supplies serve as testimony to my hypothesis” (Jowett 1952). In essence, riparian restoration and management is about “keeping water on the land longer,” and everything that is derived from streams and riparian areas results from this process.

June 1988

Today there is a twofold problem facing riparian restoration and management efforts in the West. One is the perception of “instant success,” and the other is the idea of “near-natural rates of recovery.” The first arises partially from the early comparison of livestock grazing exclosures to areas that contained improper or poor grazing strategies for the stream. The grazed areas were usually adjacent to the exclosure where there was a tendency to select sites that appeared to have the potential for a fast recovery. The exclosures commonly had some remnant vegetation, deep soils, or habitat values to protect. Some phenomenal changes were observed in stream recovery when incompatible livestock use was compared to non-use. However, it still took many years to begin to understand the true meaning of these changes. The notion of near-natural rates of recovery arose out of these same observations, and people began to expect all streams to display similar responses given the same management. This happened because differences in climate, soils, stream type, present ecological condition, upland areas, valley gradient, and a multitude of other factors were not considered to the extent necessary to draw meaningful conclusions. For these reasons and others, an upward trend, over time, in stream condition is most often assumed to be producing a near-natural rate of recovery, unless there is sound information that indicates something different.

Bear Creek
Bear Creek in central Oregon gives us a unique opportunity to observe a stream over 30 years of change. As you look at the photos of this stream, taken over a period of 30 years, imagine you are arriving at this stream for the first time and you are having to rate it on its progress and condition. Think about what you would expect the stream to look like the next year, what changes will occur from certain climatic events or changes in management practices, and, finally, what you would expect the stream to look like in 2006.

August 1993

Background
Bear Creek is located at approximately 3,500 feet elevation in the high desert of central Oregon. Precipitation averages 12 inches per year with peak runoff occurring in mid- to late February. Summer thunderstorms are fairly frequent. The area had been grazed by domestic livestock since the late 1800s, and the licensed use in 1977 was 75 animal unit months (AUMs) from April until September. Surveys during this year revealed that the riparian area totaled 2.5 acres per mile of stream and was producing approximately 200 pounds of forage per acre. That meant if livestock ate all the available forage and used 800 pounds per AUM, it took 1.4 miles of stream to support one cow/calf pair for one month. Streambanks were actively eroding, the channel was deeply incised, flows were frequently intermittent, and runoff events contained high volumes of sediment. The riparian area was storing less than 500,000 gallons of water per mile based on 30% porosity, channel cross sections, and width of the wetted floodplain.

In 1976–1978 the Bureau of Land Management (BLM) partially rested the area from grazing in an attempt to restore the productivity of the riparian area. In 1979 and 1980 the area was grazed for one week in September, and from 1981–1984 it was not grazed. Removal of juniper trees is also evident in the photographs. During 1985 the pasture was divided into three units with money supplied from the County Grazing Board and labor provided by the permittee. The grazing was changed from season-long to a three-pasture late-winter/early-spring use period (mid-February to April 15). These dates normally follow the early runoff events for this stream system. This allowed vegetation to be present for bank protection and regrowth of vegetation during the critical summer months. This regrowth also provided bank protection from summer thunderstorm events and forage for the following year.

Results
By 1992 the licensed use had increased to 300 AUMs, in 1995 the use was 327 AUMs, and in 1997 it was increased to 376 AUMs or five times the amount previously grazed from the area. The livestock permittee reportedly reduced his annual cost of hay by $10,000 because of the increased forage production, which allowed for less winter hay. In 1996 the riparian area had almost doubled from 2.5 acres per mile to 4.9 acres per mile of stream, and the production had increased tenfold to approximately 2,000 pounds of forage per acre. The filtering of sediments by the vegetation had raised the stream bed and frequent floodplain by 1 to 2 feet, and we were now storing nearly 2,096,000 gallons, over four times the original volume of water per mile. Stream length (sinuosity) had increased by one-third of a mile in the 3-mile stretch, also helping keep the water on the land longer by providing a longer path. The effects of improved riparian function were also evident in the timing and temperature of the water. Late-season flows had increased enough to provide open water throughout winter. During the hot season, the water stored in the riparian sponge maintained temperatures that were cool enough for temperature-sensitive species to survive. This was evidenced by the fact that rainbow trout returned to areas of stream that had previously been dry. Since 1996 Bear Creek and its riparian area has continued to improve. It has gone through six years of drought, two floods, and a significant rainfall event that washed out an ephemeral channel and formed a dam just downstream of the recovering reach. Photo points were frequently under 5 feet of water or more. The dam finally eroded through during the spring runoff of 2006. A lot of sediment was deposited in the two years it was a small lake, but the vegetation immediately colonized the riparian area, and the channel is now reforming.

November 1995

A visit to the site in May 2007 (30 years after the first changes in management) showed a vastly different environment. Bear Creek is a stream again, but Reed canary grass is now the dominant stabilizing species. It has changed a lot in 30 years, but primarily it has shown us that given the opportunity to take advantage of droughts and floods, a stream can make miraculous improvement. If the prescribed management does not allow this to occur, streams will not recover. It is that simple.

Conclusions
Since the mid-1970s, much has been learned in the arid and semiarid West about the compatibility of livestock grazing with the restoration and management of riparian areas. While there has been, and still is, dissention, anger, and myths surrounding this issue, people have not given up and have achieved a number of successes through applying some of these important guidelines:

• Values cannot be perpetuated until basic stream function is established.
• One grazing strategy does not fit all streams.
• Present riparian condition is very important in setting goals and objectives.
• Timing, intensity, and duration are usually more important than numbers of livestock.
• The most important factor in success is commitment by the operator.
• Upland condition must be included in any restoration program.
• Climate cycles dramatically affect restoration rates.
• Droughts are just as important as floods to riparian recovery.
• Restoration and sustainability of riparian resources occur through using the interest produced and not the capital.

April 1996

There is still a lot to learn and to do in order to restore the functionality of streams and riparian areas on a landscape scale over a broad geographic area such as the western United States. It can only occur through people working together over time on entire stream systems, which supports the need to foster ways to communicate thoughts and ideas more effectively, to set biases aside to facilitate agreement on common goals and objectives, and to do this whether the stream flows through wildland, agricultural, urban, or industrial settings. An ongoing effort called “Creeks and Communities: A Continuing Strategy for Accelerating Cooperative Riparian Restoration and Management” is aimed at addressing this with an approach to build capacity for collaborative problem solving. The initiative is led by the interagency National Riparian Service Team and implemented by a network of individuals, organizations, and institutions. To learn more about the Creeks and Communities strategy, visit http://www.blm.gov/or/programs/nrst/.

Author's Bio: Wayne Elmore is a riparian specialist and with the US Bureau of Land Management.

Author's Bio: Dennis Doncaster is a hydrologist with the US Bureau of Land Management.