(b) How and to what extent does increased sediment runoff adversely affect downstream water quality?

Answer. Assuming that sediment production is increased, it is one of a number of factors which impact water quality. It should be recognized that sediment deposition is, in some situations, a natural and needed factor in the building or maintaining of certain alluvial and coastal environments. In most situations, however, an increase in sediment loads is an adverse factor, limiting light penetration and reducing the productivity of biotic communities, blanketing spawning areas and small elements of the food chain with a destructive coating of silt, increasing water temperature through increased retention of heat, and other.

Question 28.

(a) What procedures are followed by each of the agencies to insure that project modifications (including postauthorization changes) which affect. or relate to the channelization or the effects thereof, are reported to BSFW, and that recommendations concerning fish and wildlife are reconsidered by both BSFW and the agency?

Answer. There are no formal mechanisms to report postauthorization changes to BSFW. It may be advised by letter and meet with the construction agency to discuss the significance of the modifications. The situations may range from minor changes with almost immediate construction contract letting to major changes in project sizing and location.

However, project modifications are usually reported to the Bureau by the construction agency. Changes in corps projects, particularly maintenance dredging projects, are reported to the Bureau by letter requesting our review and comments within 30 days or less. Changes in Soil Conservation Service projects are normally reported by letter requesting our review and comments within a prescribed time period. This time period varies greatly. No procedure is available to insure that project modifications installed for fish and wildlife mitigation are operated and maintained after project construction, even though these modifications are part of the authorized project. This is especially true in small watershed projects under Public Law 566. Since mitigation features are authorized to be operated and maintained for the life of the project, the time afforded the Bureau to study project modifications before they are incorporated and made official varies with each corps district. In many instances, this time is not adequate.

(b) Give examples of significant modifications of which the agency notified BSFW too late for BSFW to make an effective input into the decision to proceed with the modification.

Answer. Example will be furnished at a later date.

[NOTE. At the time this hearing went to press, the Interior Department had not provided the examples requested above. However, the General Accounting Office raised a similar question in a letter of October 6, 1972. to the BSFW. The BSFW's reply of January 16, 1973, to the GAO inquiry is as follows:]

7. (a) Do formal mechanisms exist to ensure that project modifications (postauthorization changes) are reported to BSFW, and that recommendations concerning fish and wildlife are reconsidered by both BSFW and the construction agency? What is the usual procedure followed in this situation?

Answer. There are really no formal mechanisms to report post-authorization changes to BSFW. We may be advised by letter and meet with the construction agency to discuss the significance of the modifications. The situations may range from minor changes with almost immediate construction contract letting to major changes in project sizing and location. There are occasions where we found out about significant modifications only by accident or too late to effectively enter the planning picture. On the Bighorn Project in Montana, the Bureau of Reclamation contracted to provide water for coal field development without consulting the BSFW as to impacts on fish and wildlife and the changes in project benefits that might result from any changes in stream flows, return flows, diversion structures, and the like.

Is adequate time given for BSFW study before modifications are made official? What is the usual study time allowed?

Answer:

AREA I

Construction agencies report project modifications to BSFW in ways which probably could not be classified as formal mechanisms. We believe, however, that we are kept pretty well informed. The usual procedure is notification by letter

followed by a meeting for discussion of the proposed modifications and their effects on our interests.

Study time allowed varies widely from project to project. It is strongly influenced by the magnitude of the modifications and their impact on fish and wildlife. Construction schedules also bear strongly on study timetables. Political pressures also influence the time allowed.

AREAS II AND III

Formal mechanisms which ensure that project modifications (postauthorization changes) are reported to the Bureau of Sport Fisheries and Wildlife do not presently exist.

However, project modifications are usually reported to the Bureau by the construction agency. Changes in Corps projects, particularly maintenance dredging projects, are reported to the Bureau by letter requesting our review and comments within 30 days or less. Changes in Soil Conservation Service projects are normally reported by letter requesting our review and comments within a prescribed time period. This time period varies greatly. No procedure is available to ensure that project modifications installed for fish and wildlife mitigation are operated and maintained after project construction, even though these modifications are part of the authorized project. This is especially true in small watershed projects under Public Law 566. Since mitigation features are authorized to be operated and maintained for the life of the project, the time afforded the Bureau to study project modifications before they are incorporated and made official varies with each Corps District. In many instances, this time is not adequate.

(b) If you feel this to be a problem area, give specific examples of particular problems and projects where this has been encountered.

Answer:

AREA I

We believe this to be a potential problem area, although we have not often been overextended recently.

The Teton Project might be cited as an example of what can happen without a formal mechanism. In that case we discovered during a routine field inspection that the project was under construction and modifications with serious environmental impacts were to be installed. We had not been informed.

AREAS II AND III

Caw Caw Swamp Watershed project. North Carolina (Area II). An informal agreement was made between the SCS and the North Carolina Wildlife Resources Commission to incorporate mitigation features during project construction. These features were neither coordinated with the Bureau nor implemented.

U.S. ARMY, OFFICE OF THE CHIEF OF ENGINEERS

Question 26 (a) and (e). What are the hydrologic characteristics and effects of stream channels, and how does channelization modify them?

Answer. Modification of stream channels, such as by realinement excavation, removal of snags, clearing of vegetation, placement of bottom and/or slope stabilization materials, affects their water-carrying capacity to varying degrees which consequently changes the original or natural order of flow. Secondarily, such modification alters the natural valley storage utilization during the passage of flow through a given stream reach and to a greater or lesser degree the synchronization of tributary stream contributions. Realinement of a stream channel generally shortens the reach length and thereby increases the channel slope. Increased channel slope coupled with reduced stream length produces greater velocity under the most commonly occurring natural stream conditions. Generally, excavation of channel results in reduced surface area which lowers the resistance to flow. Removal of snags (obstructions to free flow) and clearing of vegetation increases velocity of flow by reducing roughness, length of water particle paths. Placement of bottom and/or slope stabilization materials (stone riprap, vegetation and pavement) may result in either increased or decreased velocity depending on the surface roughness, configuration and other factors of the materials placed.

By the continuity equation the quality of flow per unit of time is directly related to the velocity and flow area of the channel. Increased velocity of streamflow will result in an increase in quantity of streamflow per unit of time. Therefore, for a given rate of flow, increasing the velocity will result in a decrease in area, which for normal stream geometry, produces a lesser depth of flow. The depth of flow over a reach length multiplied by the channel width is referred to as channel storage or natural valley storage. Reduced depth of flow consequently decreases the original valley storage which in turn reduces the translation time within the reach and modifies the instantaneous flow of the lower end of the reach. By the improvement of hydraulic efficiency and elimination of channel storage, flood flows transit a given reach more quickly and attain a higher peak or maximum ordinate of the flood hydrograph. Changing the time of travel in the main stream will alter the time relationships between the main channel flows and the tributary streams. Such modification may be either beneficial or detrimental, depending on the location of the reference point in relation to the respective streams.

Question 26 (b). How and to what extent does sedimentation establish or alter the effects of stream channels?

Answer. The process of sedimentation in a stream may result in either a degrading or aggrading streambed at a given location at a specified time. As the sedimentation process is highly dynamic, locations and time must be specified and generalizations can be highly misleading. Whether deposition or removal of sediment will occur in natural streams is largely dependent on the occurrence and sequence of flood flows. During major floods both removal and deposition will normally occur. As the rate of flow increases, velocities are likely to increase, producing greater tractive force which moves the bed material downstream out of a given location. Whether new material will be subsequently carried into the reach is dependent on the stability of the upstream channel bed and amount of suspended material in the water and other factors present at the time. Normally, deposition will occur during the recession of the flood as the slope of the water surface flattens, velocity decreases and suspended load may be at a maximum. Due to the interaction of the numerous factors present in the sedimentation process and the indeterminate sequence of future stream runoff events, how and to what extent sedimentation will affect stream discharge capacity can only be approximately estimated or forecast.

Question 26(c). How and to what extent do vegetation and physical developments modify the effects of stream channels?

Answer. Vegetation in stream channels can cause both beneficial and adverse effects depending on the point of view. It will serve to provide protective cover and reduce the possibility of erosion. In most cases the stream esthetics are improved by vegetation. It will also provide food and habitat for fish and wildlife. However, the larger types of vegetation can reduce the flow area in the channel and increase resistance thereby seriously lowering the flow carrying capacity of the stream. During floods, uprooted trees and other associated debris may clog bridge and culvert openings and cause more serious floodings. Cleanup of trees and other debris following a flood can be an expensive operation.

The effects of physical development on stream channels can be quite extensive. Some of the more common developments include highways and railroads crossing channels and encroachment by embankment fills. When bridge or culvert openings are too small, they restrict flow and cause higher stages upstream and lower stages downstream. Many developments either urban or agricultural encroach on stream channels and reduce the available flow area. In some cases development has completely obliterated the channels of streams with intermittent flow. Question 26 (d). To what extent does vegetation on the banks of a stream influence sediment load and behavior patterns of a stream whether channelized or not?

Answer. The major effects of vegetation on the sedimentation process in a stream are the reduction in velocity of flow and bank erosion. These items are of course directly related to each other. When the flow of a stream is slowed by vegetation or other reasons, its ability to carry sediment is reduced. Therefore, more sediment would tend to be deposited in vegetated areas than in clear channels if all other factors are similar. Erosion is reduced by vegetation because the slower stream velocity has less erosive force and vegetation provides a form of armor for the soil.

Question 27(a). What evidence exists that channelization of a stream increases sediment runoff?

Answer. Channelization of streams has in some instances increased sediment runoff because of the modification of critical hydrologic and/or hydraulic parameters. This effect has generally occurred where streamflow velocity has been increased and the protective bank cover has been reduced. Evidence of the increase in sediment runoff has been found by the observation of bank erosion where it previously was not a problem. Observation of a few bank erosion problems may not indicate a significant increase in sediment runoff. Streamflow velocities must be increased and/or protective bank cover reduced for considerable distance before significant sedimentation effects are noticed an appreciable distance downstream. Probably the best source of evidence regarding the effects of channelization on the sedimentation process is the photograph of a stream from the air prior to and after its channelization. This information is available in many of our corps offices; however, in the interpretation of the photos it is important to consider runoff conditions at the time of the photo and subsequent thereto. Evidence of changing sediment runoff may in some cases be obtained from sediment sampling stations maintained by the U.S. Geological Survey and the Corps of Engineers. Here again it is important that conditions relating to the collection of the sediment data be properly analyzed.

Question 27(b). How and to what extent does increased sediment runoff adversely affect downstream water quality?

Answer. Sediment in streamflow can cause several deleterious effects insofar as the quality of water is involved. As turbidity increases, the recreational and esthetic values of a stream tend to diminish rapidly. Water contact recreation becomes particularly unattractive. Clear water usually supports the more desirable type of fish and thus encourages sport fishing. When water is to be used for municipal and industrial uses, there are additional treatment costs associated with elimination of sediment and undesirable taste or odors. Nitrates and phosphates are often carried with sediment particles and when streamflow empties into a lake or impoundment, these elements will contribute to the euthrophication or aging of the body of water.

U.S. ENVIRONMENTAL PROTECTION AGENCY

WATER QUALITY CONSIDERATIONS (QUESTIONS 5, 27(a), 27(b))

Question 5

This question asks what are the effects of channelization on water quality. Based on the evidence included in a draft report of the Academy of Natural Sciences and on evidence from scientific papers on topics such as the effects of clear cutting on water quality, we believe that there exists a potential for moderate to severe degradation of water quality. Some of these effects may be attributed directly to the project and some are secondary impacts associated with increasing agricultural production, or an accompanying increase in urbanization. Listed below are those parameters most significantly affected.

1. Temperature. Stream channelization requires trees and shrubs to be cut down along the banks. This cuts down on the shading of the stream and consequently increases the amount of direct solar radiation. In a few cases where occasional "shade" trees have been left in place to create fish habitat, these have been largely ineffective because of increased radiation throughout the rest of the project. In fact, the increase in water temperature on some projects has limited the fish to only a few heat tolerant species of rough and bait fish such as suckers and minnows.

2. Sediment. The turbidity of the stream is usually increased because of the increase in suspended sediments. This increase in sediment load can come from a variety of sources including eroding channel banks and croplands. Secondly, sediment is not allowed to settle out as it would do under natural conditions. Basically what occurs is that the speed of the current keeps the sediment in suspension. Suspended sediment can have several environmental consequences such as attenuating light and being abrasive to fish gills. (See also discussion under 27(a) and 27(b).)

3. Nutrients. Nutrient loading may increase in streams as a result of both increased runoff and bringing more land into agricultural production. This in

crease in nutrient loading may lead to an increase in the rate of eutrophication downstream. While there are many contributory factors, the Army Corps of Engineers in their report "Environmental Reconnaissance Inventory of the State of North Carolina" quote the Carolina conservationist as saying (that in addition to nitrogen wastes from Farmers Chemical Association fertilizer plant in Tunis) "The Chowan is also threatened by nutrient runoff from over a million acres of farmland in Chowan Basin." Other evidence that channelization increases nutrient loading are studies of individual projects. These studies indicate that in several cases blue-green algae were found. These algal species are indicative of high nutrient loading.

4. Chemical. Increased chemical contamination of rivers can occur as a result of bringing more land into agricultural production and because of increased runoff. Additionally, it is not an uncommon practice to spray the channel banks to keep brush from becoming reestablished. It would be very difficult to keep these chemicals out of the stream itself. The present literature does not allow us to quantitatively estimate chemical runoff as a result of channelization. However, the evidence we do have would indicate that there exists a potentially significant effect on water quality.

Other water quality parameters are much harder to assess. For example, we would expect that the dissolved oxygen in a slow, meandering, sluggish stream would be greatly increased by channelization. (A moot point if all desirable fish are killed by temperature or habitat destruction.) We would also expect BOD levels to increase in some areas because of increased organic loading to the stream.

In summary, for question 5 there exists a potential for moderate to severe degradation of water quality. Further, we feel that stream channelization will cause and has caused severe destruction of fishery habitat. However, we will defer to the Bureau of Sport Fisheries and Wildlife to discuss these problems. Although the scientific literature in this area is not extensive, documentation for the above can be found in an attached bibliography found at the end of this enclosure.

Questions 27 (a) and 27(b)

Questions 27(a) and 27(b) focus on the relationship of channelization and sedimentation. Question 27(a) asks what evidence is there that channelization itself increases sediment runoff. Although the literature is meager, informed deductions based on elementary physical principles are possible.

In the natural state, the gradient and velocity vary in the different reaches of a stream. Material picked up in the faster portions is deposited in the wider, slower moving portions. Thus a stream tends to clear itself partially as it moves toward the mouth. Channelization tends to constrict the width of the river and shorten its overall length by removing the curves. This shortening increases the gradient. The constriction of the width and increase in gradient cause an increase of velocity which results in an increase in the stream's tendency to erode the bottom and banks and also an increase in the transporting capacity at that point. Since channelization projects are directed principally at the wider, slower moving portions the stream retains its carrying capacity throughout its entire length, resulting in sediment runoff.

Question 27 (b) zeros in on the adverse effects of sediment on downstream water quality. The general effect of fine-grained sediments such as silts and fine sands in an aquatic environment is to reduce drastically both the kinds of organisms present and their total number. The sediments alter the existing environment by screening out sunlight and changing the heat radiation. As particles settle to the bottom, they form a blanket which creates an undesirable environment for organisms which normally occur. It often smothers developing eggs of fish and also other organisms. Coarser-grained materials also blanket bottom areas to suppress bottom life. Where currents become strong, the abrasive action of these materials has a severe effect upon the benthos.

Other adverse effects of excessive sediment deposition on the stream systems or on downstream receiving waters can result from nutrients or pollutants which may be adsorbed on fine-grained soil particles. Nutrients such as phosphorus and nitrogen in generous amounts can cause accelerated eutrophication (enrichment) of waters with the accompanying increases in algal vascular plant nuisances, foul odors, and water treatment problems. Organic matter such as fatty acids, higher-order alcohols, and products of plant life also may be adsorbed to soil particles to contribute to displeasing taste and odor in water supplies.