U.S. Dept Commerce/NOAA/NMFS/NWFSC/Publications
SESSION IV: Habitat Enhancement
Session Chair: S.H. Smith, Bonneville Power Administration
EVALUATION OF RIPARIAN HABITAT REHABILITATION
William S. Platts
Don Chapman Consultants
3180 Airport Way
Boise, Idaho 83705
Prior to significant white settlement (1850), the Snake River Basin supported annual salmon runs of about 1.75 million returning adult fish. Now, only about 100,000 enter this basin each year. For the past 45 years, stream (riparian1) repair projects have been going on within this basin to enhance salmonid fishes.2 If riparian condition is not a limiting factor and everything was going right over the last 45 years in riparian rehabilitation the results would have shown by now—but they have not. We know that riparian habitats are badly degraded. Platts (1986) gave reasons why riparian habitats were in worse condition in 1986 than at any other time since Europeans entered the western United States. The drought conditions over the Snake River Basin during 1987 and 1988 further exacerbated the situation. Even though riparian habitats are in poor condition overall, water flow management continues to override in importance in the riparian ecoystem.
Riparian Repair on Water Flow Management
One of the major focuses of attention in the upper Snake River Basin has been on channel and bank repair, while the primary factor affecting declines in chinook salmon populations can be attributed to practices affecting water flow regimes.
The fate of chinook salmon in the Snake River Basin today lies not in how many logs or boulders can be dropped into the channel, but depends upon those flow regimes and flow conditions needed to take juveniles to the ocean. Secondarily, their fate is intertwined within land stewardship in the upper drainage rearing areas. I have argued for many years that good land stewardship will produce more, and at less cost, than the benefits from placing gabions, logs, and boulders in streams.
Chinook salmon survived quite well under a wide range of natural perturbations in pristine rivers and streams of the Snake River Basin. Undoubtedly the best fishery management scenario, then, is to maintain these habitats in an unaltered condition. This means, whenever possible, to concentrate on buffering or eliminating those watershed impacts that accelerated the decline in salmon populations and the condition of their habitat. These impacts or major limiting factors relate mainly to flow regimes.
There are many flow regime management concepts worthy of review. Those that could improve the status of chinook salmon are
The available money should be spent where it will do the most good and provide a favorable cost-benefit approach (Platts and Rinne 1985). The days of unlimited funding with little supervision of where and on what this money is going to be spent are about over. In the September 1989 meeting of the Idaho Water Resource Board, a representative of a large supplier of hydro-power testified that the Bonneville Power Administration had recently surpassed the $1 billion mark for fisheries mitigation. The purpose of his statement was to question if this expenditure by the rate payers was justifiable and if a product of equal value was ever delivered. Such questions will become more pointed as power surpluses disappear.
With Gramm-Rudman-Hollings Act spending restrictions soon to make drastic changes in revenue end-points, there will be real questioning whether the expenditures of any monies, whether they be federal, state, or private, are justifiable. When tough decisions have to be made—such as, do we cut catastrophic health insurance, reduce programs such as medicare and the aid to the homeless, reduce drug prevention efforts?—so this same money can be spent on an anadromous fisheries program, then mitigation funding decisions become much more critical.
In addition to direct monies being spent on rehabilitation of chinook salmon runs, decisions that have indirect effects are being made on water issues that have wide influence on regional, state, and local economies and, of course, on major fisheries. For example, the Idaho Water Resource Board has established minimum instream flows at Swan Falls Dam, which effectively limit the amount of upstream agriculture development that can occur in the Snake River Basin. Hydroelectric dams have been curtailed in the Clearwater, Salmon, and Middle Snake Rivers, primarily because of fishery values. There is now even more need to modify additional water resource management strategies in the Snake River Basin to further accommodate anadromous fish requirements. The fishery continues to make more and more demands, and rightfully so, but where is the end point of demand?
My point is that it is extremely important at this time to spend monies very wisely. Misuse of funds on one type of rehabilitation effort now will depress future efforts for more successful rehabilitation.
Habitat enhancement has both positive and negative results. The positive results are
The negative results are
Riparian repair methods have not changed much, but treatment priorities have changed during my tenure. When I first came on board in the late 1950s, one of the main stream repair methods used was the removal of large organic debris from channels; this method was used through the late 1970s. At that time it was called channel cleaning or channel maintenance and took most of the available fisheries monies. The first channel cleaning project I encountered and spoke out against got me ushered off the District. Some of this thinking is still with us and exemplifies our lack of understanding in dealing with a limited subset of habitat variables and not being able to deal with true limiting factors.
Because we have many streams in the Snake River Basin presently in an artificially stressed state and barely adequate for salmon survival, and other streams that do not naturally provide suitable habitat for salmon, we have streams that lend themselves to some type of riparian rehabilitation. There is a definite need for this stream rehabilitation analysis, however, to be done within a hydro-geologic, contact historic, and futuristic approach, while making sure it is planned under a priority system.
Streams can react violently or slowly to a stress and then naturally rehabilitate themselves quickly or slowly. Those streams with fast recovery times do not usually need monies spent trying to repair them. Those streams with long recovery time or that can never recover need careful consideration.
Long-term records of ecosystem responses to natural or artificial control are rare. Therefore, we have great difficulty visualizing the past conditions or states of a stream. Frequently, people look at a stream in a badly degraded state and firmly believe that it has always looked this way. Historic influence and changes usually go back farther than present minds can comprehend, and easily beyond documentation.
Artificial riparian repair never should be used to circumvent the real causes of stream degradation. Pouring time and money into a degraded stream that is going to be continuously disturbed is futile. A decade ago, Binns (1980) recommended that prior to installation of structures, fishing pressure should be evaluated to determine if the project is justified and if shelter is the only factor limiting the population.
Artificial stream repair should not be substituted for vigorous, responsible stewardship of the surrounding watershed. The cop-out for using stream repair in place of good land stewardship has made the overall program much weaker. The many case histories lying around out there back this statement. Also, stream repair must be done in a watershed and even in a basin perspective.
The stream and its watershed function as a unit. If the watershed is not conducive to enhancement, stream repair structures will soon cease to be productive. Few stream repair projects are compatible or fit within the needs of the valley-forming processes. The state of the art for this type of analysis has not kept up with project demand. The real test of a stream repair or enhancement project is not only if it will be cost effective but also whether or not the project survives over time in compatibility with valley-forming processes. The stream must not be divorced from its valley in the analysis.
The point in this long abstract is that it is time for the profession to ask some serious questions and develop well thought out and justifiable answers. Is riparian repair producing a favorable cost-benefit ratio? Would this money be better spent on gaining better stewardship or on the more controlling limiting factors? Is our spending of monies today being done wisely enough that it will not jeopardize future funding sources? Are we integrating spring chinook management into the needs of the complete economic system? These questions should be answered.
Binns, N. A. 1980. Improvement and evaluation of fluvial trout habitat in Wyoming. In M. E. Seehorn (coordinator), Proceedings of the Trout Stream Habitat Improvement Workshop, p. 20-23. U.S. Department of Agriculture, Forest Service, Atlanta, GA 30301.
Platts, W. S. 1986. Managing riparian stream habitats. In Proceedings of the 21st Annual Meeting, Colorado-Wyoming Chapter, American Fisheries Society, Fort Collins, CO. p. 81-86. (Available from American Fisheries Society, 5410 Grosvenor Lane, Suite 110, Bethesda, MD 20814.)
Platts, W. S., and J. N. Rinne. 1985. Riparian and stream enhancement and research in the Rocky Mountains. N. Amer. J. Fish. Manage. 5:115-125.
1Riparian is defined in this report as most federal and state agencies use the term. Riparian includes the channel, water column, streambanks, and all surrounding vegetation influenced by an almost continual water source.
2Riparian repair or riparian rehabilitation are defined in this report as any effort to increase the fish-producing potential of an already degraded habitat. Riparian enhancement is defined as any effort to increase the fish producing potential above what the habitat was capable of producing in any of its naturally occupied states.
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