Historic information and data were useful in designing the field investigation and providing a means of relating data developed during the abnormally dry years of 1976-77 to normal conditions. Appendixes A through E contain the surface water quality data developed during this study, as well as historic data. These appendices present data from the entire Klamath River drainage from Iron Gate Reservoir downstream to Hamburg. Sampling stations are shown in Plate 1, and data are arranged according to sample station number. Data for each station are arranged chronologically.

The Klamath River waters above Iron Gate Dam have as their major sources streams that drain some 4,600 square miles from Northern California and Southern Oregon and flow through several lake systems, including the Upper Klamath Lake, Copco Reservoir, and Iron Gate Reservoir. These source streams deliver waters of excellent mineral quality. The EC values range from 100 to 300 micromhos per centimeter with an average of less than 200 micromicromhos/cm measured below Iron Gate Dam. The complex operations in the upper reaches of the Klamath River involve winter runoff storage, pumpback schemes, periodic waste loadings from developed areas near Klamath Falls, and reservoir releases during periods of high algal productivity. When these delayed or modified waters are released, the downstream impact is offset or changed to the extent that a normal cyclic EC pattern does not develop.

Downstream from Iron Gate Dam, more runoff and agricultural return flows from the Shasta River system join the Klamath River. During summer low- flow conditions, the Shasta River waters, used extensively for irrigation, at times have EG values exceeding 700 micromhos/cm. Although these waters have significantly higher concentrations of dissolved solids, the impact upon the Klamath River is relatively small as the Shasta River contributes only 5 percent of the total annual inflow to the Klamath River.

Below Shasta Valley, tributary inflow adds significantly to the Klamath River flow, particularly through the Scott River. These waters have a mean EC value of 215 micromhos/cm, which is about the same as that of the Klamath River waters and therefore causes little change in the EC of the river.

A small seasonal variation in EC is notable at most Klamath River sampling stations. Figure 4 gives monthly measurements of EC for the Klamath River near Seiad Valley (F3-1430.00) covering the period 1975-84. As shown, EC values normally range from about 150 to 250 micromhos/cm and fluctuate monthly with an irregular pattern of high and low values. The EC pattern is quite variable from year to year, reflecting both the variation in precipitation and the operation of the numerous upstream storage reservoirs. The effect of the drought and reduced runoff conditions on EC in 1976-77 is apparent in Figure 4, as most of the monthly measurements are above 200 with a maximum near 350 micromhos/cm. However, in January 1978, winter runoff dropped the EC of the river water at the Seiad Valley station below 200 micromhos/cm. The maximum EC measured at this station seldom exceeded 250 micromhos/cm, which indicates a total dissolved solids content of about 175 mg/L.

In contrast to the Klamath River, the Shasta River has a greater seasonal variation and a more distinct annual pattern of EC values. Figure 5 gives the monthly measurements of EC values for the Shasta River near Yreka (F2-1050.00). As shown, these values normally range from about 400 to 700 micromhos/cm, with annual highs from July to September and lows from November to March. The EC pattern also varies from year to year due to the variation in precipitation and operation of upstream storage reservoirs. The maximum EC measured at this station seldom exceeds 750 homs/cm, which indicates a total dissolved solid content of about 525 mg/L.

The Klamath River waters are bicarbonate in character, but generally have no dominant cation. Analyses show that these waters have adjusted sodium adsorption ratios less than 3, which is considered excellent for irrigation use.

Throughout the Klamath River, chloride levels are generally low. Even when flows are low and salt concentrations highest, chlorides have not been measured in excess of 15 mg/L. In the river between Iron Gate Dam and Seiad Valley, chloride concentrations usually range from less than 1 mg/L to about 10 mg/L. The Shasta River has higher chloride levels and range between 10 mg/L and 45 mg/L; the higher levels occurring during the summer months when return flows from irrigation and developed areas make up a high percentage of the river flow. The Scott River and most of the smaller tributaries of the Klamath River have chloride concentrations of less than 10 mg/L.

The sulfate ion concentrations in the Klamath River are very similar in pattern to the total dissolved solid and chloride concentrations in that the greatest concentrations are associated with low flows In the river upstream of Iron Gate Dam. In this reach, concentrations frequently exceed 10 mg/L and have been measured as high as 70 mg/L. The downstream tributaries to the Klamath River have sulfate concentrations that are usually less than 25 mg/L.

The average boron concentration in the Klamath River is 0.1 mg/L with a maximum value found at 0.4 mg/L. Most tributaries have low boron levels; however, the Shasta River has an average concentration of 0.5 mg/L with a maxi- mum of 1.1 mg/L.

The pH of the Klamath River is quite variable, usually ranging from about 7.0 to 9.0. The highest pH values generally occur during the summer low flow periods, when biological productivity is at maximum levels.

Alkalinity also varies greatly but rarely exceeds 120 mg/L. Alkalinity levels are similar to the EC in seasonal and areal variation. The minimum levels are about 50 mg/L and occur during the winter and spring runoff periods. Although most tributaries to the Klamath River contain waters with low alkalinity, the Shasta River has moderately higher values ranging from about 150 mg/L to slightly less than 400 mg/L.

Determinations of the nutrients, nitrogen, and phosphorus were made from selected samples during the study. Nitrogen was generally present as nitrate, ammonia, and organic compounds (Appendix B). The nitrate levels in the Klamath River ranged from 0.0 to 1.6 mg/L with a median concentration of 0.42 mg/L. These levels are higher than those normally found in the rivers of Northern California; however, most of these nitrates originate in the waters upstream of the study area. The total ammonia plus organic nitrogen concentrations ranged from 0.14 to 1.7 mg/L, having a median of 0.7 mg/L in the Klamath River from below Iron Gate Dam downstream to Seiad Valley. These levels are within the range found in agricultural surface drainage and are higher than the concentrations usually found in Northern California rivers.

The dissolved orthophosphate phosphorus (PO4) concentrations in the Klamath River below Iron Gate Dam varied from 0.00 to 0.24 mg/L with a median of 0.11 mg/L. The waters downstream near Seiad Valley had concentrations that varied from 0.00 to 0.19 mg/L with a median of 0.08 mg/L. These levels are higher than normally found in most Northern California rivers but similar to that found in agricultural surface drainage. The Shasta River, with the highest concentrations Of P04, had median values of 0.15 mg/L; however, the downstream effect in the Klamath River is limited due to the relatively small flows of the Shasta River. Total phosphorus concentrations ranged from 0.00 to 0.38 mg/L, with median values of 0.20 mg/L for the river below Iron Gate and 0.11 mg/L downstream near Seiad Valley. These concentrations are also higher than those found in most Northern California rivers.

Dissolved oxygen data in Appendix A show that levels in the Klamath River are quite variable, particularly in the spring and summer when photosynthesis adds oxygen to the system and respiration consumes it. Figure 6 shows the seasonal pattern of DO levels in the Klamath River near Seiad Valley (station F3-1430.00) based on monthly daytime measurements covering the period 1958-1983. This annual pattern is typical of other Northern California rivers, having higher oxygen levels in the winter months due to the higher solubility of oxygen in cold water and lower concentrations during the months of June, July, and August, when the water is warmer and biological processes affect the system.

Data collected during diel surveys verified that the richness of the Klamath River results in fairly large fluctuations in DO during the summer months. Diel DO variations have been measured in excess of 3 mg/L at Klamath River at Randolph Collier Rest Stop (station F3-1585.00), as shown on

Figure 7. These data show the fluctuations in DO, which are typical of moderately productive water becoming supersaturated during the daylight hours, with oxygen produced during photosynthesis and dropping below Saturation due to respiration demands during periods of reduced light. Minimum DO levels generally range between 6 and 7 mg/L along the Klamath River between lron Gate Dam and Hamburg and are considered tolerable for most fisheries needs.

Diel DO levels in the Shasta River system are shown in Figure 8 and follow patterns typical of highly productive streams. This river system had larger fluctuations of DO levels along with lower minimum values than the Klamath River. Fluctuations as high as 5 mg/L occurred at Shasta River near Grenada (F2-1350.00) and a minimum value of 4.7 mg/L at Shasta River below Dwinnell Reservoir (Lake Shastina) (F2-1399.00). Lake Shastina provides down- stream releases to the Shasta River. These reservoir waters are highly productive with frequent algal blooms occurring during the warm summer months. These enriched releases could and probably have significantly reduced the downstream DO levels by creating a high Biochemical Oxygen Demand (BOD) loading caused by the decomposition of the algal mass.

Summer DO values for the Scott River at Mouth (F2-5000.00) are shown in Figure 9 and ranged from 7.6 to 9.5 mg/L. Saturation values usually remained near 100 percent, indicating a lower level of biological productivity.

Temperature and turbidity are important characteristics that influence the Klamath River's suitability for beneficial use. Each of these parameters shows significant annual variations.

Within the Klamath River system, seasonal temperature changes are large. Monthly daytime measurements made near Seiad Valley (station F3-1430.00) during the period 1958-1983 show a typical seasonal pattern, with a wide range of temperatures ranging from winter lows of about l' C in January to a summer high of 270 C in July (Figure 6).

The water temperatures measured during this investigation appear normal with summer highs near 260 C and late winter lows of 5' C. Measurements made during the diel surveys showed a consistent change at each of the stations on the Klamath River of 2' C in February, while in July the 24-hour change varied from 3.50 C to 60 C (Figure 7).

The highest peak temperatures were fairly consistent at 26' C from iron Gate Dam to Hamburg; however, the low temperatures varied with the lowest being measured at Randolph Collier Rest Stop (station F3-1585.00). The greatest diel change of 6' C measured in the Klamath River during this study was also measured at this station. At this station, streamflow characteristics and ambient temperature differences could combine to allow a greater heat loss during nighttime hours. The diel fluctuations gradually decrease to 3.5' C some 30 miles downstream at Sarah Totten Campground (station F3-1460.00).

In the upper reaches of the Shasta River, high slimmer temperatures between 22' to 28' C were observed, with temperature variations that ranged from 4' to 8' C (Figure 8). February diurnal temperature variations ranged from 2' to 4' C. At station F2-1050.00 near the mouth of Shasta River, the maximum temperature observed in July reached 29.5' C, with a temperature variation of 8' C. During the February diel, the maximum water temperature dropped to 70 C and diel variations were less than 30 C.

The high July water temperatures and associated large diurnal fluctuations in the Shasta River system could be stressful to temperature-sensitive aquatic organisms and probably make this river system unsuitable for some. These high temperature waters are, however, more desirable for most irrigation uses.

In the Scott River at station F2-5000.00, high summer temperatures ranged to about 250 C while winter lows were about 5' C (Figure 9). Summer diel variation was as great as 6' C.

Turbidity patterns in the study reach of the Klamath River are similar to those found in other rivers of Northern California in that the turbidity levels tend to increase with flow and increase in a downstream direction. In the Klamath, this pattern is also apparent but only through station F3-1470.00 near Hamburg. The station downstream near Seiad Valley (F3-1430.00) has less turbidity. This is mainly the result of inflowing tributaries such as the Scott River that are clear under normal flow conditions.

Highest turbidities usually occur during the high flows of January through April. Table 3 shows a summary of turbidity measurements at key stations where long-term monthly data were available. These data represent turbidity values from 1973 through 1983.

At these levels of turbidity, the Klamath River waters often appear turbid and usually have a brownish gray organic color, probably due to the presence of humic materials.

Suspended solids is that portion of the total solids content that can be separated from a sample by filtration, and can consist of both settleable and nonsettleable matter. These solids, as well as any nonfilterable colloidal solids directly affect turbidity by scattering or absorbing light which can greatly reduce the light transmitting properties in water. The suspended solids in surface waters normally contain both mineral and organic matter. The organic fraction, referred to as volatile suspended solids, is determined by oxidation under high temperature conditions. All classifications of the total solids found to exist in source waters are reported as concentrations in milligrams per liter.

Historic data of suspended solids concentrations in the Klamath River system is unavailable, however samples collected and analyzed during the study period indicate the great variation that exists in these waters. The median concentration found in the Klamath River between Iron Gate Dam and Hamburg was about 8 mg/L and values varied from 0 mg/L in late summer to a high of 36 mg/L during the early spring high runoff conditions. During the same period, the median concentration of volatile suspended solids was 2 mg/L with a fluctuation of 0 mg/L to a high of 5 mg/.L. In the Shasta River system, the median concentration of suspended solids was about 6 mg/L with values ranging from a low of 0 mg/.L to a high of 49 mg/L. The volatile suspended solids, with a median value of 2 mg/L, ranged from 0 mg/L to a high of 8 mg/L. The magnitude of these suspended solids appears consistent with other Northern California rivers with relatively high concentrations during winter runoff conditions and lower values during the low flow summer months. The concentrations of volatile suspended solids do indicate a relatively high percentage of organic material.

Table 3. Turbidities in the Klamath River System (1973-1983)

	Nephelometric Turbidity Units
	Minimum	Median	Maximum
Klamath River below Iron Gate Dam (F3-1599.01)	0	3	42 (a)
Shasta River near Yreka (F2-1050.00)	0	2	300 (b)
Klamath River above Hamburg Reservoir Site (F3-1470.00)	0	5	200
Scott River near Fort Jones (F2-5250.00)	0	2	220
Klamath River near Seiad Valley(F3-1430.00)	0	4	170 (c)
(a) Exceeded twice since 1962 (50 & 1000) (b) Exceeded once since 1950 (400) (c) Exceeded once since 1958 (210)

Numerous aquatic plants and animals inhabit the waters and riparian zones of the Shasta and Klamath Rivers, and many influence the water quality. Deer or deer tracks were seen In the vicinity of all stations. Cattle and horses use the Shasta River extensively and commonly have access to the Klamath River. These animals often contribute to the turbidity and add nutrients to the rivers.

Salmon, trout and some warm water fish are found in the Shasta and Klamath Rivers. Both rivers play an important role in providing habitat for spawning salmon and steelhead trout. Vascular aquatic plants are present along much of the river edges. Many of these plants are bottom-attached species that bring nutrients back into the water system from the sediments. In many reaches of the rivers, periphyton, which often includes streamers of filamentous algae, covers the river bottom. This has resulted in slippery footing conditions which are hazardous to fisherman and other recreationist.

The detailed results of benthic organism sampling and related Information on sampling methods and evaluations are included in Appendix E. Benthic samples indicate that portions of both the Shasta and Klamath Rivers contain stressed ecosystems. This is indicated by low diversities and equitability factors. The seasonal variation and assemblage of organisms indicate that a major stress is caused by the large flow variations that occur during the winter storms and spring snowmelt period. There are also indications that temperature and/or dissolved oxygen levels have also caused stress at some stations.

In the benthic macroinvertebrate samples collected from the study area, the organism densities found were characteristic of river systems with moderate to high levels of productivity. The abundance and frequent occurrence of scrapers and collectors also indicated high level of primary productivity within the systems.

Although most of the nutrients present in the Klamath River originate from upstream sources, additional nutrient sources within the drainage basin add significant amounts to the river each year. These nutrients are contributed by atmospheric sources, natural surface runoff, ground water accretion, wildlife, domestic wastes, recycling from lake sediments and other sources.

Since nitrogen and phosphorus are considered to be the two major limiting nutrients for phytoplankton production, it would appear desirable to define the magnitude of these nutrients moving through the river system. To make such a balance requires knowledge of the nutrient sources, the quantities from each source, what happens to the nutrients within the river and their final disposition.

Although data limitations make it impossible to develop a detailed nutrient balance, even an approximation of the mass flow of nutrients through the system should be useful in identifying the major sources. In this study the balance included nutrient inputs to the river from the Klamath River below iron Gate Dam, Shasta and Scott Rivers, and the minor tributaries. The down- stream Klamath River station near Seiad Valley is the control station whereby outflowing nutrients were accounted for, thus allowing the calculation of any nutrient gain or loss in the river system. An estimate of the monthly variation in nitrogen and phosphorus concentrations was made, and applied to the corresponding monthly flows. The resultant monthly tonnage values were converted to annual values for the six-year period from 1978 through 1983. These estimated nitrogen and phosphorus values entering and leaving, and net changes found to exist in the river system, are shown in Table 4.

Table 4. Klamath River Nutrient Balances

	Nitrogen (Tons)
	1978	1979	1980	1981	1982	1983
Inflow*	3900	2500	3500	2700	6000	6300
Outflow	3500	2300	3400	3000	5600	6900
Net Change	-400	-200	-100	+300	-400	+600
	Phosphorus (Tons)
Inflow*	410	280	380	340	620	770
Outflow	390	270	370	350	610	770
Net Change	-20	-10	-10	+10	-10	--
The magnitude of the inflowing nutrient sources to the Klamath River, expressed in average percentages, are shown in Table 5.

Table 5. Klamath River Nutrient Sources

	Nitrogen	Phosphorus
Klamath River below Iron Gate Dam	79	68
Shasta River near Yreka	5	10
Scott River at Mouth	9	17
Minor Tributaries	7	5

The majority of the nutrients, nitrogen 79 percent and phosphorus 68 percent, present in the Klamath River originate from sources upstream of the study area. The nutrient balance for the Klamath River suggests that between 2,000 and 7,000 tons of total nitrogen move through the river system annually with a net change from -100 to 600 tons. These net changes appear to be reasonable considering the numerous physical and biochemical processes that can store in, remove from, or add nutrients to this river system.

Annual phosphorus loadings varied between 200 and 800 tons, with net changes from -10 to +10 tons. A phosphorus loss in a river system is generally associated with deposition in bottom sediments or uptake by biological organisms. A gain of phosphorus will often be the result of higher flows that resuspend sediments or increase biological release.