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PLEASE DO NOT REMOVE FROM FILES

TECHNICAL SESSION VI WATER AND AIR QUALITY `41* .4";14.,

MAN-CAUSED FLUCTUATIONS IN QUALITY OF WATER FROM FORESTED WATERSHEDS by Robert F. Tarrant Principal Soil Scientist Forest Service, U.S. Department of Agriculture ABSTRACT Water pollution is defined as any impairment of water properties that adversely affects man directly as a living organism or indirectly through reducing the value of his physical objects or possessions or his opportunity for recreation and appreciation of nature. The changes in water quality from altered energy patterns, chemical or physical properties, or abundance of organisms therein that constitute pollution are most often the result of man's activity. Results of worldwide research indicate that man can enjoy the economic and aesthetic values afforded by forested areas and yet maintain an unpolluted supply of water. The key to producing multiple benefits from the forest, including high quality water, is the amount of care that the forest watershed manager can and will exert in all his activities. Man's actions may directly or indirectly cause changes in water quality by altering energy patterns, chemical or physical properties, or abundance of organisms therein. When such changes.adversely affect man, we call the phenomenon water pollution. Effects of water pollution may be direct - a person may become ill from drinking contaminated water. More often, however, effects of water pollution are indirect - man's economic goods are lessened in value or his opportunities for recreation and appreciation of nature are impaired. But no matter whether direct or indirect, damage to man from water pollution is almost always self-inflicted. We frequently use the abstract term water quality to refer to the suitability of a water supply for some activity of man. Water of sufficiently high quality to be consumed safely by human beings might represent the upper end of the scale, but such levels of purity would not be necessary if we were determining quality standards for water to be used as an industrial coolant. Thus, we must first assume that 'water quality" pertains to a degree of excellence or conformance to a standard for a specific use. Water quality standards, especially those pertaining to bacterial content, have long been used in many parts of the world. Man has been forced to arrive at a standard of safety to protect his health. Water quality standards also have been established, again through necessity, in many industries where water of poor quality may result in an unsatisfactory product. We are only now beginning to realize the urgent need for water quality standards to measure the success of forest land managers in maintaining a water supply of sufficiently high quality for the great variety of uses to which it may be put downstream. These include domestic water, recreation and aesthetics, support of fish and other aquatic life, wildlife, and agricultural and industrial uses.

• - 210 • 4011i When we speak of the quality of water from forested watersheds, we are necessarily limited to generalizations based on our best estimates of adequate levels. In the absence of standards, we can only say that stream water quality is adequate when man is not adversely affected either directly or indirectly by its chemical, physical, or bacteriological nature, i.e., when the water is not polluted. A large part of our future task is to establish a better understanding of the water quality goals that forest watershed managers must achieve. The chemical, physical, and bacteriological nature of stream water fluctuates constantly in response both to natural forces and to man's activities. Such fluctuations are usually related to an input, either of energy, a physical substance, or a living organism. In the following discussion, we shall examine some man-caused fluctuations in major parameters of water quality in terms of such inputs. WATER TEMPERATURE Elevation of water temperature to undesirable or even harmful levels is of most immediate concern in connection with energy inputs. Brown and Krygier (1967) have summarized the stream water temperature change process: Temperature change results from heat transfer. In the natural environment, the greatest immediate source of energy for a stream is solar radiation. Energy may be lost or gained through evaporation, condensation, conduction, or convection; but these processes usually affect stream temperature less than solar radiation. The amount of heat received at the stream surface is also influenced by several nonclimatic variables, including surrounding vegetation; topography; stream channel characteristics; inflow of surface water and groundwater; and area, depth, and velocity of the stream. Change in stream temperature depends on the total heat received and the total volume of water heated. Shallow streams at low flows are most responsive to incoming heat. Research results all point to the strong effect exerted on water temperature when shade from streamside vegetation is reduced. Titcomb (1926) found that daily temperature maxima of many streams in northeastern United States were as much as 32.2° C. In one instance where vegetation had been removed from the streamside for a distance of 0.8 kilometer, water temperatures were increased by as much as 5.5° C over those of shaded portions of the stream. Chapman (1962) also found that stream water temperature was raised by 5.5° C in logged areas in Oregon. Greene (1950) compared temperatures of streams flowing through forested watersheds and through open farmland. Over a year's time, maximum weekly temperatures of stream water from the forested watershed were noticeably lower than those from the open watershed. A difference of as much as 7.2° C was noted in the month of May. Stream water temperatures on the farm watershed decreased from 27 to 20° C after flowing only 400 feet through forest cover. Eschner and Larmoyeux (1963) showed that clearcutting resulted in stream temperature increases to levels greater than those that can be tolerated by trout. Careful partial cutting, on the other hand, did not produce such elevated water temperatures. Hornbeck and Reinhart (1964) found that, following clearcutting of a deciduous forest, maximum water temperature increased by 8° F and minimum temperature decreased by 3.5° F. Under the pattern of scattered clearcuts commonly used in the Douglas fir region, little or no increase in maximum stream temperatures would be expected unless a large proportion of the streambed was directly exposed to solar radiation (Levno and Rothacher, 1967). On a northwest facing slope, extensive logging on a forested watershed increased maximum water temperature only after 55 percent of the drainage was logged and timber had been felled along all the major stream channels. In this study, mean monthly water temperature increased by as much as 6.7° C during the period from April through August, following direct exposure of the stream channel by scouring during the previous winter's record flood.

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After a forest was clearcut in the Coastal Ranges of Oregon, the daily temperature change of stream water was increased by 8° C during the warmest period of the year (Brown and Krygier, 1967). When streamside vegetation was removed, the mean monthly maximum temperature during September was also increased by 8° C. Brown and Krygier showed also that when streamside vegetation was removed in the Cascade Range of Oregon, water temperature increased by 9° C during midday. These authors point out that small stream systems have low summer flows and a large surface area in relation to water volume. Thus, small streams may reflect microclimatic changes brought about by streamside vegetation removal to a degree not often noticed on larger streams which have greater heat capacity. Any of the following conditions related to temperature are considered detrimental to public water supply (Anonymous, 1968): water temperature higher than 29° C; more than 3° C water temperature increase in excess of that caused by ambient conditions; any water temperature change which adversely affects the biota, taste and odor, or the chemistry of water; any water temperature variation or change which adversely affects water treatment plant operation; 5. any water temperature change that decreases the acceptance of the water for cooling and drinking purposes. Brown (1969) showed that temperatures of small streams can be accurately predicted, even on an hourly basis, by using an energy balance technique. On three streams from forested watersheds in Oregon, Brown predicted hourly temperature changes ranging from 0 to 9° C. His predictions were accurate within 0.6 C more than 90 percent of the time. The energy budget technique offers valuable information which can be applied to control water . temperature by manipulating streamside vegetation. In some cases, stream produttivity might be increased by judiciously raising water temperature. In most cases, however, low water temperatures are greatly desired during the warm part of the year, and an undesirable elevation of temperature constitutes pollution. MICROBIAL POPULATIONS A certain level of most bacteria groups is always present. However, we can assume that land management activities which alter water temperature and chemistry can lead to increases or decreases in the number of organisms present. As human populations rapidly increase, the neglected subject of bacterial populations in streams from forested watersheds will necessarily receive greater research attention. Bacteriological standards for raw water specify maximum levels of 10 000 colonies for 100 milliliters of water for total coliform and 2 000 per 100 milliliters for fecal coliforms, on a basis of monthly arithmetic averages and an adequate number of samples (Zeller, 1969). The total coliform limit may be relaxed if fecal coliform concentrations, considered indicators of recent and possibly dangerous pollution, do not exceed the specified limit. The presence of other coliform organisms suggests less pollution or contributions from nc fecal sources. Coliform content appears to be closely correlated with nitrate content, at least in ground water (Borts, 1949). Whether this association is valid also for stream waters is not known. Even maximum possible protection entirely safeguard the purity of of coliform and Escherichia coli Coliform densities were found to presence of cattle in the stream coliform density.

or degree of isolation of forested watersheds cannot water. Petersen and Boring (1960) reported on densities serotypes present in two semi-isolated streams in Colorado. be quite uniform over much of the sampling period, but the and drainage from flood irrigation both steeply increased

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Kunkle and Meiman (1967) measured bacterial groups in water from mountain watersheds in Colorado. Total, coliform, fecal Streptococcus, and fecal coliform bacterial groups were closely related to the physical parameters of the stream and were especially dependent on the "flushing effect" of runoff from snowmelt and rain, summer storms, or irrigation. The seasonal trend for all bacterial groups was similar: (1) low counts prevailed while the water was at 0o C, although bacteria from all groups were isolated during winter; (2) high counts appeared during rising and peak flows caused by June snowmelt and rain; (3) a short "postflush" decrease in bacterial counts took place as the runoff receded in early July; (4) high bacterial counts were again found in the July-August period of warmer temperatures and low flows; and (5) counts declined in September. There is some evidence that the forest floor can act as a bacterial filter. Nikolaenko (1962) found snowmelt water that had passed through a strip of forest on the bank of a reservoir contained fewer bacteria than water that had not passed through the forested strip. Probably the major source of fluctuations in bacterial content that can lead to pollution levels in stream water is the presence of human beings in forested watersheds. Forest workers and recreationists are major sources of dangerous organisms in stream water. Concentrations of livestock or big game animals are also potential sources. The causes of variation in bacterial numbers of a small, unpolluted stream were studied by Morrison and Fair (1966). These authors concluded that the most important cause was summer rainstorms of short duration, which cause overland flow. When streamflow is stable during periods of no precipitation, bacterial numbers can be related to the size of the waterstreambed contact surface. As streamflow increases after precipitation, bacteria are deposited in the ground water associated with the stream and are later released into the stream as it recedes. Bacterial numbers fluctuate during the winter even when temperatures o are as low as 0-5.5 C. When cattle graze in marshy areas adjacent to the stream, the bacterial density of the stream also rises. If bacterial content of stream water is to be kept below pollution levels, strict attention must be paid to all sources of potential contamination by living organisms. The discharge of wastes from railroad trains passing through forested watersheds has become a problem (Anonymous, 1961). Discharge of fecal waste, garbage, waste water, or other polluting materials from any land or air conve y ance passing through or over watersheds is a potential source of bacterial pollution. While these examples are perhaps of minor importance in the overall problem, such sources of potential bacterial contamination warrant mention as they will increase as populations increase. SUSPENDED SEDIMENTS Natural erosion occuring at low rates on undisturbed areas is not often harmful to water quality. Man's activities, however, can greatly accelerate the erosion process, causing sediment loads in streams that are intolerable in terms of our definition of water pollution. Preventing excess sedimentation is not difficult, requiring as it does only intelligent care in all land management activities (Wallis, 1963). This point is well documented in the literature, but attaining forest practices that will assure minimum sediment loads is sometimes difficult. Thus, the role of the watershed manager is vitally important in controlling water pollution caused by suspended solid material. The effects of forest treatments associated with timber harvesting have been reviewed in detail by Packer (1967). These studies show generally that streams flowing from undisturbed forests contain only small amounts of suspended sediment and quality of their waters is usually suitable for drinking purposes. Timber cutting may substantially increase streambank erosion caused b y increased streamflow peaks. Logging can sometimes increase sedimentation considerably, depending on the location and drainage of skidways, she erodibility auU stoniness of soils, and the rapidity of revegetation of skidways. Forest roads that are inadequately drained or located too close to streams are often the main cause of high sediment content in streams frcm forested watersheds (Rothacher and Glarebrook, 1968).

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Along with physical soil disturbance, the removal of vegetation by fire is a significant cause of sediment in stream waters (Rich, 1962). Other papers presented in this seminar deal extensively with the problem of suspended sediments so there is little need of discussing further how soil particles reach flowing streams. The results of fire and logging operations on suspended sediment content of forested streams are perhaps better documented than any other area of the water quality problem. DISSOLVED SOLIDS Studying nutrient cycling in small watersheds may be an efficient means of better understanding the problems of occurrence and fluctuations of chemicals in stream water (Bormann and Likens, 1967). In such a study of the forest ecosystem, budgets for calcium, magnesium, potassium, and sodium were calculated by Likens et al. (1967). These authors found that chemical balances in small, well-defined terrestrial ecosystems may be fairly well determined. With the possible exception of potassium, they found a net loss of the major alkalies and alkaline earths from the system, but on the assumption that the biota in soils of the ecosystem are near dynamic equilibrium, they believe loss of all the chemicals listed is counterbalanced by chemical decomposition of underlying bedrock and till. Nitrogen is the nutrient element of perhaps greatest interest in the forest situation. Some evidence has been offered (Smith et al., 1968) to indicate that complete removal of forest vegetation leads to an increase in chemoautotrophic activity which in turn might lead to increased nitrate in stream water of denuded watersheds. Further work by Bormann et al. (1968) suggests that complete denudation of a forest ecosystem tends to deplete the nutrient capital. In the small stream system studied by these authors, nitrate concentrations have exceeded 10 parts per million for more than 1 year after all trees were removed and the remaining vegetation killed with chemicals. Algal blooms appeared during the summer after this extreme treatment. The nitrate concentration in stream water from this denuded watershed increased from 0.9 milligrams per liter before all vegetation was removed to 53 milligrams per liter 2 years later. This nitrate mobilization was equivalent to all other net cationic increases and anionic decreases observed in the drainage water (Likens et al:, 1969). The topographical character of the watershed and texture of the soil strongly affects the amount of suspended sediments, dissolved solids, and organic matter. Tikuishis (1965) showed for several watersheds in northwest Russia that up to 45.07 tons per square kilometer per year of dissolved solids were discharged into one river. The most intensive chemical erosion was noticed in watersheds in which the soil consisted largely of sand or clay. Less intensive chemical erosion was found where soils were of sandy loam texture, and the least erosion was found in pure sand. As the forested area increased, the discharge of dissolved solids, organic matter, and suspended sediments decreased under the same topographical conditions. A good example of the effect of such amounts of dissolved solids in water is given by Bartsch (1968) who stated that when only 11 grams of phosphorus or 454 grams of nitrogen are mixed with 1 acre-foot of water, objectionable algal growth occurs. Precipitation has also been shown to be important in determining the chemical content of stream water. The chemical content of precipitation entering one small forested system formed a major portion of that of the drainage effluent (Johnson et al., 1966); 410 kilograms per square kilometer of chlorine passed through the system during 1 year (Juang and Johnson, 1967), two-thirds of which was provided by precipitation. The role of precipitat on in adding chemicals to the forest ecosystem and thus to streamflow varies greatly according to geographic location. In some parts of the world, usually the interior regions of larger continents, rainfall contains enough nitrogen to be a significant source of plant nutrition. Most of this nitrogen is derived from land materials or industrial pollution. Tarrant et al. (1968) have shown, on the other hand, that coastal Oregon rainfall contains very little nitrogen, because it is influenced dominantly by the ocean. Over a year's time, only 1.49 kilograms per hectare of nitrogen was brought to the soil surface in rain falling on a coastal Oregon site. Of this small total, only about 0.19 kilograms per hectare is considered to be a real addition of nitrogen from the atmosphere. The remaining

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1.30 kilograms per hectare is only a local redistribution of airborne organic material. It is difficult to extend research findings on inputs of chemicals through precipitation outside the geographical area in which the studies have been conducted. Ashes washed or blown from burned areas may add significantly to the dissolved load of streams. Strong effects usually are found only in the first season after the burn, but changes in chemical quality of streams draining a burned area may endure for several seasons. Such effects of fires, however, are not always noted. Johnson and Needham (1966) found no specific effect of a forest fire on ionic composition of stream water in California. These authors postulated that ash constituents were dissolved by light rainfall and leached into the permeable forest soil before the first snow. Because of the acidic nature of the soil, the dissolved cations were absorbed on the exchange complex rather than washed directly into the stream. As with suspended sediments, effects of forest management practices and amount of soil and vegetation disturbance play a large part in the extent to which stream water chemistry may be altered. Perhaps the most important point is that considerations other than those of economics need to be included in determining the best methods of forest watershed management for maintaining high quality water. Species composition of the forest stand may also affect the composition of rainwater passing through the canopy. Voigt (1960) showed that stemflow from red pine (Pinus resinosa) and eastern hemlock (Tsuga canadensis) contained more nutrients than did stemflow from beech (Fagus grandifolia). Greater amounts of potassium were extracted by rainwater in September than in May, and calcium was leached from hemlock and beech in greater quantities than from red pine during the fall. Tarrant et al. (1968b) showed that total nitrogen in throughfall precipitation was nearly five times greater beneath red alder (Alnus rubra) than in rainfall collected in open areas. Nitrogen was almost four times greater beneath a mixed stand of alder and conifers and about three times greater under conifers. Annual contribution of nitrogen to the forest floor was shown to be as much as 112 kilograms per hectare beneath a red alder stand, compared with only 36 kilograms per hectare beneath conifers (Tarrant et al., 1969). Attiwill (1968) found for eucalyptus (E. obliqua) litter that the loss of elements follows the order sodium > potassium> magnesium > phosphorus. He compared his findings for phosphorus with those for litter of some Russian hardwoods and suggested that the two plant systems diffei with kcpcLL tu the cycling and mobility of phosphorus within the living biomass. Slack and Feltz (1968) showed that water quality in a small stream was related to autumn leaf fall from riparian vegetation. As the rate of leaf fall increased, dissolved oxygen and pH decreased, and water color, specific conductance, iron, manganese, and bicarbonate values increased. Stream quality improved rapidly following channel flushing during storms. Thus organic loading by tree litter can exert significant impact on water composition, especially during periods of low flow. ECONOMIC CHEMICALS Over the past quarter century, many new synthetic compounds, including pesticides, have been dispersed throughout the world in great amounts, and living things have been exposed to chemicals with which they had had no previous contact. Residues of these novel compounds have been introduced into soil, air, vegetation, and water where they persist for varying lengths of time and, presumably, contribute to interactions affecting various life processes. Greatly intensified forestry practices will be necessary to meet needs of the rapidly growing world population. Insecticides, herbicides, silvicides, and many other economic chemicals are new tools that contribute substantially to realizing increased forest production goals. Many of these chemicals will continue to be used, and forest managers have a strong responsibility to guard against possible environmental contamination.

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Many herbicides and their carriers, when used responsibly, can be employed in forest vegetation control with minimum impact on water quality (Tarrant and Norris, 1967). After several years' study, Norris (1967) concluded that following application of phenoxy and amitrole herbicides, some herbicide residue will appear in nearly all streams which flow by or through treated areas. The maximum concentration of these residues is a function of the proportion of the watershed treated, the amount of stream included in the treatment unit, the ratio of the surface area of the stream to its volume, and the degree to which brush overhanging the stream intercepts spray materials. The persistence of residues is a function of the hydrologic nature of the area treated, and nearly all the herbicide found in stream water results from direct application of spray materials to the water's surface. Phenoxy and amitrole herbicides degrade in forest floor material (Norris, 1968a, 1969a, 1969b). If herbicides are applied before the beginning of the dry season of the year, their degradation over a dry period of 1 or more months is usually sufficient to prevent any entry of these chemicals into streams when the first rains end the dry period. When chemicals are applied near the end of the dry period, residues may or may not be found in stream water after the first rain storms according to the intensity of precipitation (Norris, 1968b, 1969c). If the first rains following the dry period are gentle, any residues remaining after late application will move down into the surface mineral soil and thus not run off. On the other hand, if the first rain storms are sufficiently intense to cause overland flow, some herbicide residue is generally found in stream water at that time. The amount of chemical applied in the forest has a strong bearing on the amount of residue available for movement into stream water. Moore et al. (1969) studied the persistence of phorate, a highly toxic systemic insecticide. In one treatment, this chemical was applied at 112 kilograms per hectare, a rate sometimes used for individual tree treatment in high value stands such as seed-producing areas. At this experimental rate, 98 percent of the total chemical applied was still present in the forest floor and soil after 6 months. Presumably, rapid degradation of the chemical was prevented because it greatly reduced soil microbial populations. Again, as with other sources of pollution, the literature shows that preventing contamination of water is usually possible if the forest manager takes certain precautions. The one precept that should be followed when applying economic chemicals to forested watersheds is most simple: If you do not want the , chemical in stream water, don't put it there! This means, of course, that care must be taken to apply the chemical only to land surfaces and only in situations where the possibility of its movement from land to water is low. CONCLUSIONS Water quality is a relative term, the meaning of which varies with intended use of the water. In the absence of well-defined standards of quality for waters flowing from forested watersheds, we can perhaps do no more at this time than relate water quality to the broad concept of pollution levels of the various parameters of water quality. For this purpose, water pollution is defined simply as any impairment of water properties that adversely affects man directly as a living organism or indirectly through reducing the value of his physical objects or possessions or his opportunity for recreation and appreciation of nature. It is apparent that the changes in energy patterns, chemical or physical constitution, or abundance of organisms in forest waters that do constitute pollution are most often the result of man's activity. Results of research throughout the world indicate also that it is possible for man to enjoy the economic and aesfhetic values afforded by forested areas and yet maintain an unpolluted supply of water. The key to producing multiple benefits from the forest, including high quality water, is the amount of care that the forest watershed manager can and will exert in all his activities.

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LITERATURE CITED Anonymous. 1961. Watershed control for water quality management. Pollut. Contr. Counc., Pacific Northwest Area. 36 pp. Anonymous. 1968. Water quality criteria. Rep. Nat. Tech. Adv. Comm. to the Secretary of the Interior. Fed. Water Pollut. Contr. Admin. 234 pp. Attiwill, P.M. 1968. The loss of elements from decomposing litter. Ecology 49: 142-145. Bartsch, A. F. 1968. Eutrophication problems and progress, appendix G, pp. G-1--G-7. In Minutes of 152nd meeting, Northern Basin Interagency Comm., Bismarck, N. Dak. Bormann, F. H., and G. E. Likens. 1967. Nutrient cycling. Science 155: 424-429. Bormann, F. H., G. E. Likens, D. W. Fisher, and R.S. Pierce. 1968. Nutrient loss accelerated by clear-cutting of a forest ecosystem. Science 159: 882-884, illus. Borts, I. H. 1949. Water-borne diseases. Amer. J. Public Health 39: 974-978. Brown, George W. 1969. Predicting temperatures of small streams. Water Resources Res. 5: 68-75. Brown, George W., and James T. Krygier. 1967. Changing water temperatures in small mountain streams. J. Soil Water Conserv. 22(6): 242-244. Chapman, D. W. 1962. Effects of logging upon fish resources of the West Coast. J. Forest. 60: 533-537. Eschner, A. R., and J. Larmoyeux. 1963. Logging and trout: four experimental forest, practices and their effect on water quality. Prog. Fish Cult. 25: 59-67. Greene, G.E. 1950. Land use . and trout streams. J. Soil Water Conserv. 5: 125-126. Hornbeck, J. W., and K.C. Reinhart. 1964. Water quality and soil erosion as affected by logging in steep terrain. J. Soil Water Conserv. 19: 23-27. Johnson, C. M., and P. R. Needham. 1966. Ionic composition of Sagehen Creek, California, following an adjacent fire. Ecology 47: 636-639. Johnson, N. M., G. E. Likens, F. H. Bormann, and R. Pierce. 1966. Bulk chemical changes and rate of chemical weathering in central New Hampshire. Trans. Amer. Geophys. Union 47: 83-84. Juang, F. H. T., and N. M. Johnson. 1967. Cycling of chlorine through a forested watershed in New England. J. Geophys. Res. 72: 5641-5647. Kunkle, Samuel H., and James R. Neiman. 1967. Water quality of mountain watersheds. Colo. State Univ. Hydrol. Pap. 21. 53 pp. Levno, Al, and Jack Rothacher. 1967. Increases in maximum stream temperature after logging in old-growth Douglas-fir watersheds. Pacific Northwest Forest & Range Exp. Sta. U.S.D.A. Forest Serv. Res. Note PNW-65. 12 pp., illus. Likens, G. E., F. H. Bormann, N. M. Johnson, and R. S. Pierce. 1967. The calcium, magnesium, potassium, and sodium budgets for a small forested ecosystem. Ecology 48: 772-785.

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Likens, Gene E., F. H. Bormann, and Noye M. Johnson. 1969. Nitrification: importance to nutrient losses from a cutover forested ecosystem. Science 163: 1205-1206. Moore, D. G., E. E. Holcombe, and R. F. Strand. 1969. Phorate persistence in a forest soil. (Abstr.) Northwest Sci. 43:40. Morrison, S. M., and J. F. Fair. 1966. Influence of environment on stream microbial dynamics. Colo. State Univ. Hydrol. Pap. 13. 21 pp. Nikolaenko, V. T. 1962. The effect of forest on the drinking quality of water. Lesn. Hoz. 15(12), 1962(59). /Russ.] Norris, L. A. 1967. Chemical brush control and herbicide residues in the forest environment, pp. 103-123. In Proc. herbicides and vegetation manage. symp., Oreg. State Univ. Norris, Logan A. 1968a. Recovery of amitrole from forest litter, pp. 31-32. In Res. progr. rep., Western Soc. Weed Sci. Norris, Logan A. 1968b. Stream contamination by herbicides after fall rains on forest land, pp. 33-34. In Res. progr. rep., Western Soc. Weed Sci. Norris, Logan A. 1969a. Degradation of several herbicides in red alder forest floor material, pp. 21-22. In Res. progr. rep., Western Soc. Weed Sci. Norris, Logan A. 1969b. Some chemical factors influencing the degradation of herbicides in forest floor material, pp. 22-24. In Res. progr. rep., Western Soc. Weed Sci. Norris, Logan A. 1969c. Herbicide runoff from forest lands sprayed in summer, pp. 24-26. In Res. progr. rep., Western Soc. Weed Sci. Packer, Paul E. 1967. Forest treatment effects on water quality, pp. 687-699. La International symposium on forest hydrology, William E. Sopper and Howard W. Lull /eds.]. _ Pergamon Press, New York. Petersen, Norman J., and John R. Boring, III. 1960. A study of coliform densities and Escherichia coli serotypes in two mountain streams. Amer. J. Hyg. 71: 134-140. Rich, L. R. 1962. Erosion and sediment movement following a wildfire in a ponderosa pine forest of central Arizona. Rocky Mountain Forest & Range Exp. Sta. U.S.D.A. Forest Serv. Res. Note RM-76. 12 pp. Rothacher, Jack S., and Thomas B. Glazebrook. 1968. Flood damage in the National Forests of Region 6. Pacific NorthwestForest & Range Exp. Sta. U.S.D.A.Forest Serv. 20 pp.,illus. Slack, Keith V., and Herman R. Feltz. 1968. Tree leaf control on low flow water quality in a small Virginia stream. Environ. Sci. Tech. 2: 126-131. Smith, W. H., F. H. Bormann, and G. E. Likens, 1968. Response of chemoautotrophicnitrifiers to forest cutting. Soil Sci. 106: 471-473. Tarrant, R. F, and L. A. Norris. 1967. Residues of herbicides and diesel oil carriers in forest waters: a review, pp. 81-88. In Proc. herbicides and vegetation manage, in forests, ranges and noncrop lands symp., Oreg. State Univ. Tarrant, R. F., K. C. Lu, C. S. Chen, and W. B. Bollen. 1968a. Nitrogen content of precipitation in a coastal Oregon forest opening. Tellus XX: 554-556. Tarrant, Robert F., K. C. Lu, W. B. Bollen, and C. S. Chen. 1968b. Nutrient cycling by throughfall and stemflow precipitation in three coastal Oregon forest types. Pacific Northwest Forest & Ranee Exp. Sta. U.S.D.A. Forest Serv. Res. Pap. PNW-54. 7 pp.

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Tarrant, Robert F., K. C. Lu, W. B. Bollen, and J. F. Frankin. 1969. Nitrogen enrichment of two forest ecosystems by red alder. Pacific Northwest Forest & Range Exp. Sta. U.S.D.A. Forest Serv. Res. Pap. PNW-76. 8 pp. Tikuishis, R. V. 1965. The effect of chemical erosion on sedimentation in lakes, pp. 156-159. In Rep. Symp. on Hist. of Lakes in Northwest of U.S.S.R. (Leningrad). Titcomb, J. W. 1926. Forests in relation to fresh water fishes. Trans. Amer. Fish. Soc. 56: 122-129. Voigt, G. K. 1960. Alteration of the composition of rainwater by trees. Amer. Midland Nat. 63: 321-326. Wallis, James R. 1963. Logging for water quality in northern California. Pacific Southwest Forest & Range Exp. Sta. U.S.D.A. Forest Serv. Res. Note PSW-N23. 7 pp. Zeller, Howard D. 1969. Stream standards and water supplies. J. Amer. Water Works Ass. 61: 131-132.

Reproduced from the 1970 Proceedings of the Joint FAO/U.S.S.R. International Symposium on Forest Influences and Watershed Management, Moscow, U.S.S.R. by the FOREST SERVICE, U.S. Department of Agriculture,

for official use.

GPO 987-524