Water Quality of Bear Creek Basin, Jackson County, Oregon

By Loren A. Wittenberg and Stuart W. McKenzie

U.S. GEOLOGICAL SURVEY Water-Resources Investigations Open-File Report 80-158

Prepared in cooperation with the Rogue Valley Council of Governments and the Oregon Department of Environmental Quality

1980 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, Secretary GEOLOGICAL SURVEY H. William Menard, Director

For additional information write to: U.S. GEOLOGICAL SURVEY P. 0. Box 3202 Portland, Oregon 97208 Contents Page Conversion factors ------Abstract------1

PART I - EXECUTIVE SUMMARY Introduction------5 Identified water uses in Bear Creek basin------6 Water-quality standards------6 Reference levels------9 Water-quality problems in Bear Creek basin------10 Irrigation-water assessment------n On-farm use------11 Pastures------12 Cultivated orchards ------14 Row crops------14 Irrigation-cana1-and-stream system------14 Talent Irrigation District------14 Medford Irrigation District------16 Rogue River Valley Irrigation District------16 Whetstone Creek------17 Bear Creek and tributary assessment------17 Conclusions------31

PART II - TECHNICAL DISCUSSION Background------37 Basin description------37 Hydrologic system------37 Past investigations------39 Irrigation-water assessment------40 On-farm use------40 Pa sture s------40 Cultivated orchards------43 Row crops------47 Irrigation-canal-and-stream system------47 Talent Irrigation District------50 Medford Irrigation District------51 Rogue River Valley Irrigation District------54 Whetstone Creek------56 Comparison of waters at points of irrigation diversion and Bear Creek at Kirtland Road------56 Bear Creek and tributaries------58 Emigrant subarea------59 Ashland subarea------62 Talent subarea------65 Phoenix subarea------68 Medford subarea------72 Central Point subarea------75

iii Page

Bear Creek and tributaries--Continued Diel sites------79 DissoIved oxygen------80 pH -- 85 Specific conductance and alkalinity------90 Ammonia and nitrite------90 Periphyton------93 Benthic invertebrates------95 References cited------97

PART III - WATER-QUALITY CHARACTERISTICS

Water-quality characteristics and cause-effect relationships------105 Discharge------105 Temperature------105 Suspended sediment------107 Turbidity------108 Specific conductance and dissolved solids------108 Dissolved oxygen------109 pH- - 110 Nitrogen------111 Phosphorus------H2 Indicator bacteria------112 Total coliform bacteria------112 Fecal coliform bacteria------113 Fecal streptococci bacteria------113 Use of indicator bacteria data in irrigation practices------114 Glossary of selected terms------115

IV Illustrations [Plate is in pocket]

Plate 1. Map showing water-quality sampling sites in Bear Creek basin, Jackson County, Oregon Page Figure 1. Map showing source, conveyance, and distribution of irrigation water in Bear Creek basin------7 2. Map showing the six subareas in Bear Creek basin------19 3. Graph showing percentage of measurements that did not meet the State standard for dissolved oxygen in six subareas of Bear Creek basin------21 4. Graph showing percentage of measurements exceeding the maximum State standard for pH in six subareas of Bear Creek basin------22 5. Graph showing percentage of fecal coliform concentrations exceeding State standards in six subareas of Bear Creek basin------23 6. Graph showing percentage of fecal streptococci measure ments greater than 1,000 bacteria per 100 mL in six subareas of Bear Creek basin------24 7. Graph showing variation in turbidity values in six subareas of Bear Creek basin------25 8. Graph showing variation in suspended-sediment con centrations in six subareas of Bear Creek basin------27 9. Graph showing variation in nitrate concentrations in six subareas of Bear Creek basin------28 10. Graph showing variation in Kjeldahl nitrogen con centrations in six subareas of Bear Creek basin------29 11. Graph showing variation in orthophosphate concen trations in six subareas of Bear Creek basin------30 12. Map showing location of study area in Rogue River basin ------.._._...... 33 13. Graph showing number of outflow-inflow ratios (for indi vidual farms) showing concentrators, diluters, sources, and sinks for fecal coliform, suspended sediment, and dissolved nitrate in pastures and orchards------46 14. Map showing Talent Irrigation District------50 15. Map showing Medford Irrigation District------52 16. Graph showing suspended-sediment concentrations at selected sites in Phoenix Canal during 1976 irrigation season------53 17. Graph showing nitrate concentrations at selected sites in Phoenix Canal during 1976 irrigation season------54 18. Map showing Rogue River Valley Irrigation District------55 19. Graphs showing diel fluctuations of water-quality parameters and solar radiation for Bear Creek at Barnett Road at Medford (site 104), August 16-17, 1977 81

v \

Page

Figure 20. Graphs showing dissolved oxygen and related data at diel sites in Bear Creek basin------84 21. Graph showing comparison of minimum dissolved oxygen with ultimate biochemical oxygen demand in Bear Creek basin------85 22. Graph showing pH and related data at diel sites in Bear Creek basin------87 23. Graph showing comparison of diel pH fluctuations with diel dissolved-oxygen fluctuations in Bear Creek basin------88 24. Graph showing comparison of diel pH fluctuations with diel water-temperature fluctuations------89 25. Graph showing specific conductance, alkalinity, pH, and discharge data at diel sites in Bear Creek basin------91 26. Graph showing mean monthly discharges for 1959-77 water years------106

VI Tables Page

Table 1. Median ratios of selected water-quality char acteristics of water samples from pastures and orchards------12 2. Median values of selected water-quality char acteristics of inflow and outflow water samples------13 3. Number of times water-quality standards or reference levels were not met in irrigation-delivery canals and streams------15 4. Sources of stored water for irrigation districts------39 5. Ratio of outflow to inflow samples for selected water-quality characteristics from pastures------41 6. Inflow and outflow values for selected water- quality characteristics from pastures------42 7. Ratio of outflow to inflow samples for selected water-quality characteristics from cultivated orchards------44 8. Inflow and outflow values for selected water- quality characteristics from cultivated orchards------45 9. Ratio of outflow to inflow samples for selected water-quality characteristics from row crops------48 10. Inflow and outflow values for selected water- quality characteristics from row crops------48 11. Median water-quality characteristics in irrigation waters of canals and streams------49 12. Quality characteristics of water diverted for irrigation and water leaving the Bear Creek basin, May-September 1976------57 13-18. Water-quality median values for subareas of Bear Creek basin: 13. Emigrant subarea------60 14. Ashland subarea------63 15. Talent subarea------67 16. Phoenix subarea------70 17. Medford subarea------73 18. Central Point subarea------77 19. List of diel sites ------79 20. Summary of diel data relating to dissolved oxygen------82 21. Summary of data collected at diel sites relating to PH------86 22. Concentrations of ammonia and nitrite nitrogen in Bear Creek during 1977 diel studies------92 23. Summary of 1977 periphyton data from Bear Creek------94 24. Summary of 1977 benthic invertebrate data from Bear Creek------96

vii Conversion factors for inch-pound system and International System Units (SI)

[For use of those readers who may prefer to use metric units rather than inch-pound units, the conversion factors for the terms used in this report are listed below:]

Multiply inch-pound unit By To obtain metric unit

Length

inch (in.) 25.40 millimeter (mm) mile (mi) 1.609 kilometer (km)

Area

square mile (mi2 ) 2.590 square kilometer (km ) acre 4,047 square meter (m2 ) acre-foot (acre-ft) 1,233 cubic meter (m3 )

Volume per unit time (includes flow) cubic foot per second (ft3 /s) 0.02832 cubic meters per second (m3 /s) gallon per minute (gal/min) 0.06309 liters per second (L/s) million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3 /s)

Mass ton (short, 2,000 Ib) per day (ton/d) 0.9072 tonne per day (t/d)

Temperature degree Fahrenheit (°F) 5/9 after subtracting 32 degree Celsius (°C)

Energy per unit area per time

British thermal unit per square foot Calorie per square cm per min per minute (Btu/ft2 /min) 0.2712 (calorie/cm2 /min)

Vlll Water Quality of Bear Creek Basin, Jackson County, Oregon

By Loren A. Wittenberg and Stuart W. McKenzie

ABSTRACT

Samples of water in the Bear Creek basin were collected from irrigation and return-flow channels on farms and from canals and streams for analysis of physical, chemical, and biological characteristics. These data, along with measured flows, were used to identify major surface-water-quality problems in the basin and, where possible, their causes or sources. This report includes three parts--executive summary, technical discussion, and explanation of water-quality characteristics.

Irrigation and return-flow data collected on farms show that pastures are sources of fecal coliform and fecal streptococci bacteria and sinks for sus pended sediment and nitrite-plus-nitrate nitrogen. Orchards act as concen trators of these constituents. Water in the canals shows a general degra dation of quality in a downstream direction and in a down-basin direction from one canal system to another.

Bear Creek and its tributaries have exhibited dissolved oxygen and pH values that do not meet Oregon Department of Environmental Quality water- quality standards. From the Talent subarea to the Central Point subarea, 40 to 50 percent of the fecal coliform and fecal streptococci concentrations were higher than 1,000 colonies per 100 milliliters during the irrigation season. Also, during the irrigation season, suspended sediment averaged 35 milligrams per liter and turbidity values averaged 15 Jackson turbidity units; both these averages were about double those for the nonirrigation season in lower Bear Creek basin. Nitrite-plus-nitrate concentrations in streams were significantly greater downstream from a sewage-treatment plant and from points of ground- water seepage. A significant source of Kjeldahl nitrogen and orthophosphate in Bear Creek is sewage-treatment-plant effluent.

The marsh on Whetstone Creek reduces the bacteria, suspended sediment, turbidity, and nitrite-plus-nitrate concentrations that are contributed by irrigation-return flows.

PAGE 5 NEXT INTRODUCTION

The U.S. Geological Survey has undertaken the identification of major surface-water-quality problems in Bear Creek basin and their causes or sources The objective of this study is to provide information to evaluate methods for minimizing problems within the basin. To meet this objective, the Geological Survey began a data-collection program in 1976 that included the following elements:

1. Measurement of the quality and quantity of water in the irrigation- canal -and -stream system.

2. Measurement of the quality and quantity of water delivered to and leaving selected irrigated farm plots.

3. Measurement of the quality and quantity of water in selected streams in Bear Creek basin.

4. Intensive water-quality measurements in the main stem of Bear Creek, including physical, chemical, and biological characteristics (diel studies).

5. Collection of data on precipitation, quality and quantity of storm- water runoff, and combined sewer overflow in four subbasins within Bear Creek basin.

Data collection for the first element was completed in 1976, and for the second, third, and fourth elements in 1977. These data were reported by McKenzie and Wittenberg (1977) and Wittenberg and McKenzie (1978). Data col lection for the fifth element was completed in 1978 (Wittenberg, 1978).

This report presents an interpretation of data collected in the first four elements of the study. Because of funding restrictions, interpretation of the data collected in the fifth element of the study is not planned. The report is divided into three parts part I, executive summary; part II, tech nical discussion; and part III, explanation of water-quality characteristics.

Irrigation is a requirement for agriculture in the Bear Creek basin. Without the use of stored water in the basin and importation of water from outside the basin, low-flow or no-flow conditions would occur in most creeks during late summer and early fall. The irrigation water is distributed by the Talent, Medford, and Rogue River Valley Irrigation Districts. Water is diverted from streams within Bear Creek basin and from the Klamath River basin to the east and the Little Applegate River basin to the southwest through a series of canals and natural streams receiving irrigation-supply water and irrigation-return flow (see fig. 1). \ Identified Water Uses in Bear Creek Basin

The Oregon Department of Environmental Quality (1977) has identified the following beneficial uses of water from Bear Creek:

1. Public domestic water supply (designation for this use is presently under study)

2. Industrial water supply

3. Irrigation (including water for frost protection of orchards)

4. Livestock watering

5. Anadromous fish passage 6. Salmonid fish rearing

7. Salmonid fish spawning

8. Resident fish and aquatic life

9. Wildlife and hunting

10. Fishing

11. Boating

12. Water-contact recreation

The Department of Environmental Quality also includes esthetic quality in its list of beneficial uses.

To provide a quality of water adequate to meet the above identified uses, the Oregon Department of Environmental Quality (DEQ) has set water-quality standards as shown in the following section.

Water-Quality Standards State water-quality standards have been set by DEQ (1977) for temperature, turbidity, dissolved oxygen, pH, and "organisms of the coliform group where associated with fecal sources" for which the fecal coliform test is used. The temperature and turbLdity standards apply only to point sources. Those State standards that are used in this report as listed as follows: IrrigBtion distribution system -- Bear Creek drainage basin

Base from the State Water Resources Board, Ropue Drainage Basin, 1970

Figure 1.-Source, conveyance, and distribution of irrigation water in Bear Creek basin. 7 Characteristic State standard

Dissolved oxygen (percent Not less than 90 saturation)

pH (units) Within range of 6.5-8.5

Fecal coliform Not greater than 1,000 (except (colonies/100 mL) during storm conditions)

As used in this report, a State standard is not met when a measured value falls outside the criteria range listed above. DEQ (1977) water-quality standards include the statement "Where the natural quality parameters of water * * * are outside the numerical limits of * * * water quality standards, the natural water quality shall be the standard." Although a value is outside the criteria range listed above, it may not be outside the range of "natural water quality" that is undefined by DEQ at this time. This often occurred with dissolved oxygen and pH data collected over 24 hours (diel data).

Reference Levels

The authors have selected reference levels for certain water-quality characteristics to help identify causes of wat;er-quality problems, sources of constituents, and to aid in interpreting data in this report. These refer ence levels were arbitrarily selected for use as comparative values and often are equal to natural or background water-quality values. These levels are not standards and should not be used as such by readers of this report. Their use in another area of the State or country would be of questionable value. The reference levels are as follows: Reference level Characteristic (maximum)

Suspended sediment (mg/L) 20

Turbidity (Jtu) 15

Dissolved un-ionized ammonia as N .02 (mg/L)

Dissolved nitrite as N (mg/L) .06

Dissolved nitrite-plus-nitrate as N 1.0 (mg/L)

Dissolved orthophosphate as P .06 (mg/L)

Fecal streptococci (colonies/100 mL) 1,000

The following is a brief discussion of how each of the reference levels was chosen. \

Suspended sediment - 20 mg/L.--This concentration is approximately equal to the discharge-weighted average of all irrigation water at or near points of diversion listed in table 12 (part II). The reference level gener ally is exceeded in streams during periods of overland runoff resulting from storms.

Turbidity - 15 Jtu (Jackson turbidity unit).--This value was arbitrarily chosen and is higher than that recommended by the National Technical Advisory Committee (1968). The reference level in streams generally is exceeded during periods of overland runoff resulting from storms.

Dissolved un-ionized ammonia as N - 0.02 mg/L.--This concentration was chosen to agree with the recommended criterion of the U.S. Environmental Pro tection Agency (1976). The value is one-tenth of the lowest values shown to be toxic to some species of freshwater aquatic life.

Dissolved nitrite as N - 0.06 mg/L.--At or below this concentration, nitrite should not harm salmonid fish (U.S. Environmental Protection Agency, 1976). This high concentration is unlikely to occur in natural surface water. Dissolved nitrite-plus-nitrate as N (hereinafter referred to as nitrate) - 1.0 mg/L.--This concentration is arbitrarily chosen. Nitrate at this concentration is known to cause algal blooms in lakes. As discussed by Rickert and others (1977b), nuisance algal growths in rivers are believed to be controlled by:

1. Low water temperatures 2. High summertime turbidities 3. Scarcity of certain trace nutrients 4. Short detention time in the stream system Dissolved orthophosphate as P - 0.06 mg/L.--Orthophosphate is that portion of the total phosphate that is readily available to plants. When nitrate has a concentration of 1.0 mg/L, the reference level of 0.06 mg/L of orthophosphate is near the desirable ratio (16N:1P) of nutrients to support plant growth (Stumm and Morgan, 1970; Kramer and others, 1972). Fecal streptococci - 1,000 colonies/100 mL.--A concentration equal to the State standard set for fecal coliform has been selected as the reference level because the two indicator bacteria groups may have a similar source--fecal material.

Water-Quality Problems in Bear Creek Basin

A water-quality problem exists when a characteristic of water (a con stituent or property of water) decreases its suitability or prevents its use for some intended purpose. Three examples of water-quality problems are bacteria in drinking water, high turbidity in a municipal supply, and a large amount of oxygen-demanding material in a stream.

10 To correct water-quality problems, the water can be treated to remove its use-limiting characteristics, as is done at water-treatment and sewage- treatment plants; or the undesirable characteristics can be prevented from entering the water. The methods for correcting a problem can best be deter mined by understanding (1) the use of water and, thus, the quality of water needed; (2) how water quality is measured; (3) what water-quality data mean; and (4) the causes or sources of water-quality problems.

La Riviere, Quan, Westgarth, and Culver (1977) identified several questions that needed to be answered in order to identify and minimize water- quality problems in Bear Creek basin. These questions, along with answers, are shown on pages 31 to 33.

IRRIGATION-WATER ASSESSMENT

During the 1976 irrigation season, water from canals and selected streams was sampled by the Geological Survey to identify water-quality problems. In an attempt to isolate the sources of the problems, a followup study was made by sampling irrigation inflow and outflow water at farm plots during the 1977 irrigation season.

The irrigation method and crop type generally will determine whether a farm plot acts as a concentrator or diluter of constituents in water or as a source or sink. Explanations of these terms are shown below.

CONCENTRATION (weight/volume)

Outflow greater than inflow = Concentrator Outflow less than inflow = Diluter

LOAD (weight/time)

Outflow greater than inflow = Source Outflow less than inflow = Sink

On-Farm Use

In an effort to avoid the large expense of continuous monitoring of characteristics in irrigation water entering and leaving farm plots, the study used a "random-sample" approach. This means that some time after the water was turned on, and some time after water commenced running off the farm plot, inflow and outflow samples were taken. Generally these samples were taken at the same time. Inflow and outflow concentrations and outflow dis charge can vary as much as 100 percent of the mean value during a period of irrigation (L. A. King, U.S. Department of Agriculture, oral commun., June 1977). When considered together, however, all irrigation plots containing the same type of crop are assumed to constitute a random sampling, and pro vide estimates of the average and range of water-quality changes produced by farm plots containing that crop.

11 Samples of inflow and outflow water were taken from pastures, orchards, and row crops. During the 1977 growing season, most of the orchards were under cultivation to limit the growth of grass and weeds. Tables 1 and 2 show the median ratios (outflow/inflow) and mean values, respectively, of selected water-quality characteristics for outflow and inflow water samples for pastures and orchards. Table 1.--Median ratios (outflow/inflow) of selected water-quality characteristics of water samples from pastures and orchards

Pasture Orchard Concen Concen Characteristic tration Load tration Load ratio ratio ratio ratio

Fecal coliform 4.0 1.6 2.6 0.48

Fecal streptococci 7.5 3.4 2.0 .82

Suspended sediment .37 .07 2.7 .31 Dissolved nitrate as N .27 .04 5.9 1.1 Total Kjeldahl nitrogen 2.4 .59 -- -- as N

Dissolved orthophosphate 1.1 .30 1.2 .49 as P

Pastures As indicated in table 1, pastures are sources of bacteria. In all but two pastures sampled, the outflow water contained fecal coliform bacteria con centrations in excess of the State standard. Fecal streptococci bacteria con centrations for all outflows from pastures exceeded reference levels. Bacteria in water flowing from pastures are probably a combination of those already in the water and bacteria picked up in the pastures from fecal matter of birds, livestock, and other warmblooded animals.

Pastures tend to filter suspended sediment from the water, and thus they are sinks for sediment and Kjeldahl nitrogen. Pastures also act as concen trators of Kjeldahl nitrogen. Both nitrate concentrations and loads decreased, probably due to rapid uptake by the pasture grasses. The dissolved oxygen was below 90 percent saturation in all but one sampling of water flowing from pastures.

12 Table 2.--Median values of selected water-quality characteristics of inflow and outflow water samples [Approximate number of analyses of water for each crop type were pasture, 13; orchards, 15; beet seed, 2; grass seed, 1]

Pasture Orchards Beet seed Grass seed Characteristic Inflow Outflow Inflow Outflow Inflow Outflow Inflow Outflow

Turbidity (Jtu) 25 5 15 25 9 12 9 5 Specific conductance 180 175 220 230 325 500 305 350 (umhos/cm at 25°C) pH (units) 7.9 7.5 7.9 7.2 7.7 7.2 7.6 7.4 Temperature (°C) 16 17 17 19 17 17 15 15 Dissolved oxygen (percent saturation) 96 81 99 92 77 29 91 76 Cultivated Orchards

Orchards act as sinks for indicator bacteria; they also act as concen trators and contribute to higher concentrations of bacteria in return-flow streams or lower canals. The greater concentration of bacteria in the outflow water (table 1) may be attributed to the following: (1) concentrating of bacteria already in the water into a smaller volume, and (2) loss of bacteria from the inflow water and a subsequent gain of other bacteria in the orchard from droppings of birds and other warmblooded animals.

Ratios in table 1 indicate that orchards act as sinks and concentrators for suspended sediment. Orchards are also sources of turbidity in streams and lower canals receiving irrigation-return flow. Nitrate-load ratios show no loss or gain for orchard farm plots. The sixfold increase in concentration, however, identifies orchards as concentrators of nitrate.

Median temperature values of water sampled from pastures and orchards show small increases from inflow to outflow samples (see table 2).

Row Crops

Insufficient samples were collected from row crops for a detailed inter pretation, but some conclusions can be drawn. Harvested beet-seed fields were found to be sources of indicator bacteria and orthophosphate. Dissolved- oxygen mean concentration was 29 percent of saturation in outflow water from the beet-seed fields.

The partly burned grass-seed field was a sink for indicator bacteria, suspended sediment, nitrate, and a source of orthophosphate. Dissolved oxygen was below 90 percent saturation.

Irrigation-Canal-and-Stream System

The irrigation-canal-and-stream investigation included water-quality sampling near points of diversion, near the ends of the canals, and from selected return-flow streams. This sampling was done between March and October 1976. A generalized downstream degradation of water quality within each canal system and in a down-basin direction from one canal system to another was observed. The repeated reuse of water is a significant factor in the degraded quality. A summary, by irrigation district, of water quality in the canals and streams is presented in table 3. Talent Irrigation District

The Talent Irrigation District (TID) includes the Ashland, East, West, Talent, and Lower East Laterals (see figs. 1, 14). Meyer and Payne Creeks are streams receiving irrigation-return flow, also in the TID area.

14 Table 3.-Number of times water-quality standards or reference levels were not met in irrigation-delivery canals and streams in Bear Creek basin [In "Indicator bacteria" column, Fc=fecal coliform and FS=fecal streptococci. In columns where a fraction is shown, the denominator indicates a number of measurements that differs from the number listed under "Number of samples collected." For example, % means one occurrence in four samples]

Number Indicator Ortho- Irrigation of bacteria Suspended Dissolved phos district Canal and drainage samples Fc Fs sediment Turbidity oxygen PH Nitrate phate

Talent Ashland Lateral 10 0 0/6 1 0 0 1/6 0/8 0/8 East Lateral 10 0 0/6 5 6 0 1/8 0/8 1 West Lateral 5 0/4 0/4 5 5 0 0/4 0/4 0/4 Meyer Creek 7 3/6 2/5 2 0 0 0 0/6 0/6 Payne Creek 6 5 4/4 5 5 1 0 0 0 Talent Lateral 10 3 4/6 4 3 0 0/8 0/8 0/8 Lower East Lateral 3 2 2/2 1 0 0 0 0/2 1/2

Medford Medford Irrigation District Canal 11 4 3/7 11 6 0 2/10 0/9 2/9 Phoenix Canal 27 9/26 8/17 20/2$ 14 1 3/23 1/22 20/22

Rogue River ' Valley Hopkins Canal (east side) 15 5 3/8 10 6 1 2/14 0/12 7/12 Lone Pine Creek 6 1/5 1/5 0 0 0 0 0/5 5/5 Bear Creek Canal and Hopkins Canal (west side) 10 3 5/6 7 2 3 2/8 1/8 7/8 Whetstone Creek 7 0 1/5 1 0 1 2/6 0/6 2/6 Table 3 shows that fecal coliform concentrations exceeded the State standard of 1,000 colonies per 100 mL at four of seven creeks and laterals sampled. High concentrations of fecal streptococci were also present at these same sites. These high concentrations are probably caused by irrigation- return flow, animals, and domestic sewage. The suspended-sediment concen trations and turbidity values are greater than the reference levels and may be caused by cattle damaging canal banks, channel scour, and irrigation-return flow. Emigrant Reservoir is one source of the turbidity in the canals. Values of the pH exceeding the State standard for pH in the Ashland and East Laterals are associated with high dissolved oxygen and high temperature, sug gesting the cause to be biological productivity. Ground-water seepage may be the source of increased concentrations of nitrate. The source of orthophosphate in the Lower East Lateral is not known. Because the water in Lower East and Talent Laterals contains irrigation-return flow and ground water, it is more degraded than water in Ashland and East Laterals, which contains little or no irrigation-return flow.

Medford Irrigation District

The Medford Irrigation District (MID) includes the MID and Phoenix Canals (see figs. 1, 15). Sources of fecal bacteria, suspended sediment, and turb idity in the MID Canal include tail water from the East Lateral in addition to to all previously identified sources.

The water in the Phoenix Canal, diverted from Bear Creek at Talent, is of poorer quality than that in the other canals discussed thus far. Sewage- treatment-plant (STP) effluent, which enters Bear Creek via Ashland Creek, is a major source of nutrient concentration in the canal; degradation, however, is also due in part to repeated reuse of the water for irrigation. Suspended sediment and nutrients in the Phoenix Canal show a seasonal trend, and other canal systems probably follow a similar trend.

Rogue River Valley Irrigation District

The Rogue River Valley Irrigation District (RRVID) includes the Hopkins and Bear Creek Canals (see figs. 1, 18). The quality of water in the canal near its diversion at Bradshaw Drop is similar to that of the tail water of Ashland Lateral. Water in the lower part of the Hopkins Canal (east side of Bear Creek basin) includes water diverted from Lone Pine Creek. The quality of water in the canal below its confluence with Lone Pine Creek is better than the quality above the confluence. This is an example of how augmentation with high-quality water can improve the water quality of canals and streams. The high-quality creek water is overflow from the Medford Aqueduct (the municipal water supply for the city of Medford) plus some irrigation-return flow.

Table 3 shows that Bear Creek Canal, containing water diverted from Bear Creek at Jackson Street, and Hopkins Canal (west side of Bear Creek basin) have the poorest quality of water of any of the canals. This may be caused by a combination of reuse of water for irrigation, effects of sewage-treatment- plant effluent, and ground-water inflow.

16 Whetstone Creek

Whetstone Creek, which contains ground water and irrigation-return flows, drains an area south and west of White City. The creek flows through a marsh and empties into the Rogue River below the Medford STP. Water sampled from the creek near its mouth had lower concentrations of bacteria, suspended sedi ment, and nitrate, and lower turbidity levels than did other streams contain ing irrigation-return flow (Meyer and Payne Creeks). Filtration by rooted vegetation apparently results in settling of suspended sediment and reduction of turbidity in the creek. State standards for pH were not met in two of six samples. Water of Whetstone Creek is similar in quality to the tail water of the Ashland lateral.

BEAR CREEK AND TRIBUTARY ASSESSMENT

This part of the report summarizes the water-quality data available for Bear Creek and its tributaries. To aid in interpretation, the data are divided as follows:

1. Six data sets representing the six subareas, as shown in figure 2.

2. Two hydrologic regimens:

a. Nonirrigation season and base flow (nonirrigation regimen).-- The nonirrigation regimen includes samples collected (1) during fall, winter, and early spring (to March 31); (2) when no over land flow resulted from storms; and (3) when the streamflows were not high from recent storms.

b. Irrigation season and base flow (irrigation regimen).--The irri gation regimen includes samples collected (1) during the irriga tion season (April through September), and (2) when there was no overland flow resulting from storms.

3. Dissolved-oxygen and pH data collected between 9 a.m. and 4 p.m. (nondiel data) are separated from the diel data collected over a 24-hour period.

Figures 3 through 6 illustrate the percentage of measurements that did not meet State standards in each of the subareas. Figures 7 through 11 are plots of average values for each of the subareas.

Analysis of the water-quality data shows the following:

1. The data for each subarea indicate no apparent long-term trends.

2. Eight percent of the nondiel measurements on Bear Creek and tribu taries and 41 percent of the diel measurements on Bear Creek were lower than the State standard (90 percent of saturation) for dis solved oxygen (DO). The large incidence of oxygen deficiency related to the diel measurements is partly due to the loss of DO at night as the result of respiration of aquatic life. Other causes of

17 low DO concentrations include (a) bacterial oxidation of organic material from point and nonpoint sources, and (b) oxidation of ammo nia from sewage-treatment-plant effluent to nitrite and then nitrate (nitrification). A reduction in biochemical oxygen demand (BOD) and ammonia in the stream would help to prevent the DO from dropping below the State standard.

The percentage of measurements that did not meet State standard for DO in each subarea is shown in figure 3. The Emigrant subarea in cludes no sewage-treatment-plant effluent and little irrigation- return flow. The Ashland and Talent subareas include sewage-treatment- plant effluent and irrigation-return flow. Most of the water con taining the sewage-treatment-plant effluent is diverted out of Bear Creek for irrigation downstream from the Talent subarea. Irrigation- return flow is the main source of water to Bear Creek downstream from the Talent subarea. The DO data in the Talent subarea tributaries met State standards. No significant difference was noted between irrigation and nonirrigation seasons. The large percentage of low DO concentrations measured at the Bear Creek site in the Talent subarea appears to be the result of BOD and ammonia loading from the sewage-treatment-plant effluent.

3. The difference between diel and nondiel measurements is less for pH data (fig. 4) than for dissolved-oxygen data because high pH (exceed ing State standards) occurred during the day, when both diel and non diel data were collected. Water in the three upstream subareas was within State pH standards except for a few pH values observed in Bear Creek where there were few periphyton (microscopic plants and animals attached to submerged material in streams). A high percentage of the pH measurements were outside the State standard in the three down stream subareas, where there were large numbers of periphyton.

4. As shown in figures 5 and 6, bacteria concentrations were highest (a) during the irrigation regimen and (b) in the four downstream subareas of Bear Creek basin. During the irrigation regimen, there was a higher number of fecal streptococci than fecal coliform bacteria. Figure 6 shows that tributaries to Bear Creek generally have higher concentrations of fecal streptococci bacteria than does the main stem.

Indicator bacteria concentrations appear to be associated with the activities of man. For example, higher concentrations are found during the irrigation season, when activity on the land is greatest; and near urbanized areas, where the population density is greatest. Man may be a contributor of indicator bacteria, but the animals associated with man may also be significant contributors.

5. Figure 7 shows that average turbidity is high in the Emigrant subarea. Emigrant Reservoir is a we11-documented source of turbidity (Pugsley, 1972). Because of irrigation-return flow, the lower four subareas also have high turbidities. During the 1977 water year

18 B»« from tb» »t^ W»t«t Roftt* D«te«f» B^to, 1970 80

EXPLANATION

- Diel data O 70 -O- Nondiel data Q LU 72 Number of measurements > O (/>

DC 60 O LL Occ < Q z

S 40 5

O Z

20 104

119

10 176

Emigrant Ashland Talent Phoenix Medford Central Point SUBAREAS OF BEAR CREEK BASIN ( Direction of flow -) Figure 3.-Percentage of measurements that did not meet the State standard for dissolved oxygen in six subareas of Bear Creek basin.

21 PERCENTAGE OF MEASUREMENTS EXCEEDING THE MAXIMUM STATE STANDARD FOR pH 8 -» ro w « o O O o

I 30 m OT » tr8 13

OD 2 ^to 5'CL 00 u o ^

s.0) 3- ^ o I 50

EXPLANATION -O Nonirrigation regimen data Irrigation regimen data 65 40 20 Number of samples 67

106

UJ CC 230 UJ o go. £2 820

Emigrant Ashlandx Talent Phoenix Medford Central Point SUBAREAS OF BEAR CREEK BASIN (Direction of flow )

Figure 5. Percentage of fecal coliform concentrations exceeding State standards in six subareas of Bear Creek basin.

23 PERCENTAGE OF FECAL STREPTOCOCCI MEASUREMENTS GREATER THAN 1000 COLONIES PER 100 MILLlLITERS -n S

§ & * 8-i O~* °

x o O O m o> C O m 3 ro 2" 0. 8 3 CO * c z DO (5 2 3 "1CD 3 p st S6' 2.x o> -, 7T <0 C3- ^

o8 *- o O. o 3 24

EXPLANATION

20 Nonirrigation regimen data Irrigation regimen data

E 16 O m cc D I- Z O O 12

Q m OC 8

Emigrant Ashland Talent Phoenix Medford Central Point SUBAREAS OF BEAR CREEK BASIN (Direction of flow -)

Figure 7. Variation in turbidity values in six subareas of Bear Creek basin.

25 (a drought year), the turbidity of the water at several sites de creased significantly, suggesting a direct relation between flow and turbidity.

6. Average suspended-sediment concentrations are highest in the four lower subareas of Bear Creek basin, as shown in figure 8. The irrigation-regimen and nonirrigation-regimen data for suspended sedi ment show the same pattern as those for turbidity and have a common cause (irrigation-return flow). The higher suspended-sediment concen trations in the Talent subarea during the nonirrigation regimen, and possibly during the irrigation regimen also, are probably caused by sand from sluicing of Reeder Reservoir. Data on the amount of sedi ment transported downstream during storms, which is generally the period when most sediment is transported, are not included in figure 8.

7. Figure 9 shows the average concentration of nitrate in various subareas of Bear Creek basin. Nitrate concentrations in the main stem are higher in the Ashland, Talent, and Phoenix subareas than in the Emigrant subarea. This increase is attributed to sewage-treatment- plant effluent. The nonirrigation main-stem nitrate concentrations in the Ashland subarea are low because most of the nitrogen is in the form of ammonia which is not oxidized to nitrate until it moves farther downstream. The irrigation main-stem nitrate concentration in the Phoenix subarea is less than in the subareas just upstream, probably because of (a) the rapid uptake of nitrate by periphyton as ammonia is being oxidized, and (b) dilution by irrigation-return flows. Ground water containing high concentrations of nitrate seeps into the streams, causing high concentrations of nitrate in the Medford subarea nonirrigation tributary samples and also in all the Central Point subarea samples.

8. Figure 10 shows a small increase in mean Kjeldahl nitrogen concen trations in a downstream direction. A significant source of the Kjeldahl nitrogen, composed mainly of ammonia nitrogen, is sewage- treatment-plant effluent.

9. Average orthophosphate concentrations in figure 11 show a similar pattern to Kjeldahl nitrogen, and, again, sewage-treatment-plant effluent is a significant source. In general, water-quality problems (1) increased during the irrigation regimen and (2) decreased during the low flows of the 1977 water year. Sewage- treatment-plant effluent, ground-water seepage, and irrigation-return flow probably have the most significant effects on water quality in the Bear Creek basin.

26 50 1 I

EXPLANATION Nonirrigation regimen data >- Irrigation regimen data 40

30 5 z (-* 5UJ 5 20 a LU Q z UJ OL V) to 10

Emigrant Ashland Talent Phoenix Medford Central Point SUBAREAS OF BEAR CREEK BASIN (Direction of flow

Figure 8. Variation in suspended-sediment concentrations in six subareas of Bear Creek basin.

27 1.6

EXPLANATION Nonirrigation- regimen data 1.4 Irrigation- regimen data Tributary sites Main-stem sites

1.2

2 1.0 a.

0.8

0.6

0.4

0.2

Emigrant Ashland Talent Phoenix Medford Central Point SUBAREAS OF BEAR CREEK BASIN (Direction of flow

Figure 9. Variation in nitrate concentrations in six subareas of Bear Creek basin.

28 1.6

EXPLANATION -O Nonirrigation regimen data 1.4 - Irrigation regimen data Tributary sites Main-stem sites

1.2

1.0

0.8

I < 0.6 Q

0.4

0.2

Emigrant Ashland Talent Phoenix Medford Central Point SUBAREAS OF BEAR CREEK BASIN (Direction of flow )

Figure 10. Variation in Kjeldahl nitrogen concentrations in six subareas of Bear Creek basin.

29 1.2

EXPLANATION O Nonirrigation regimen data

1.0 " ~ Irrigation regimen data ~ Tributary sites Main-stem sites

0.8

5 z «* * 0.6 V)

0.4

0.2

Emigrant Ashland Talent Phoenix Medford Central Point SUBAREAS OF BEAR CREEK BASIN (Direction of flow )

Figure 11 . Variation in orthophosphate concentrations in six subareas of Bear Creek basin.

30 CONCLUSIONS

Water-quality characteristics that could limit or prohibit some of the water uses shown on page 6 are listed below by source:

1. Sewage-treatment-plant effluent.--Ammonia, nitrite, nitrate, and organic nitrogen; total phosphate and orthophosphate; and organic material, as measured by ultimate biochemical oxygen demand (BODU) and total organic carbon (TOG).

2. Combined-sewer outflow.--Organic material, fecal bacteria, and low DO.

3. Log-pond outflow.--Turbidity, suspended sediment, organic material, and ammonia. The log pond discharged water to Bear Creek during most months of 1977, even during extended periods of very little rainfall (Edison Quan, Oregon Department of Environmental Quality, oral commun., May 15, 1978).

4. Ground-water seepage.--Nitrate.

5. Irrigation-return flow.--Suspended sediment, turbidity, and nitrate from orchards; orthophosphate from pastures; and fecal bacteria from both orchards and pastures.

One area in the Bear Creek basin that shows a high quality of water is Whetstone Creek. The wetland area of Whetstone Creek acts as a "living filter," removing some turbidity, suspended sediment, nitrogen, phosphorus, and bacteria from the water.

Irrigation-related activities that could improve the quality of water are listed below:

1. When irrigation of farm plots is controlled so as not to allow out flow to occur and normal irrigation-return flow is left in streams, water quality of streams will not be directly affected by irrigation- return flow and the quality should improve.

2. Ponds or settling basins can remove some suspended sediment and turbidity-causing materials from irrigation-return flows.

3. The irrigation of pastures removes from water some nitrate, suspended sediment, and other turbidity-causing material. This suggests that grass-lined waste ditches and grass cover in orchards could improve irrigation-return flow quality.

31 The following questions posed by La Riviere, Quan, Westgarth, and Culver (1977, p. 22) are answered by the authors of this report.

1. What are the sources of contamination by fecal bacteria and how can the sources of bacteria be controlled?

Sources of fecal coliform bacteria include combined sewers; irrigation-return flows, especially from pastures; and overland flow. Reduction of combined-sewer and irrigation-return flows could reduce the concentration of fecal coliform bacteria.

2. What benefits can be derived from augmenting Bear Creek flows?

Depending on the source of water and its characteristics, in creased flows in Bear Creek could (a) increase DO concentrations; (b) aid in holding pH below 8.5; (c) decrease turbidity; and (d) decrease concentrations of fecal coliform, fecal streptococci, ammonia, nitrite, nitrate, orthophosphate, and suspended sediment in Bear Creek. Increased flows could also improve the quality of water available from canals for irrigation.

3. What are the man-related sources of suspended sediment in the basin?

Suspended sediment results from overland flow of surface water; point sources, such as combined sewers and industrial outfalls; and the sluicing of Reeder Reservoir. Overland flow includes storm-water runoff as well as irrigation-return flow. Any land-use activity that leaves the soil exposed to erosion contributes to increased concen trations of suspended sediment in the streams. These activities in clude (a) construction of homes, office buildings, and highways; (b) agricultural practices, such as row-crop cultivation, plowing, and disking; and (c) timber harvesting. All these practices either disturb existing vegetative growth or leave the soil devoid of vegetation. 4. What methods can be used to minimize the suspended-sediment problem in the basin?

Suspended-sediment problems can be minimized by controlling or eliminating erosion. This is accomplished by (a) reducing overland flow, (b) minimizing the creation of erosive areas, and (c) inter cepting suspended sediment before it reaches the streams. Some irri gation methods, such as sprinkler and drip, help to reduce overland flow. The use of settling ponds and (or) grassed waterways for transporting return flows will remove some suspended sediment from the water. 5. What Best Management Practices will minimize the turbidity problems related to irrigation water?

Generally, reduction of suspended sediment will also help to reduce turbidity. Pastures are especially effective in removing turbidity-causing material.

6. What are the impacts of ammonia concentrations from sewage-treatment- plant effluent on fish and on aquatic insects? No direct impact of ammonia on aquatic insects was noted. Un ionized ammonia exceeded reference levels in Bear Creek several times, as did nitrite from oxidation of ammonia.

7. What is the impact of the nutrients from sewage-treatment-plant effluent on primary productivity? Sewage-treatment-plant effluent is the primary source of nitrogen and orthophosphate to Bear Creek. These nutrients, along with the particle size of' the streambed material, are believed to control bio logical productivity.

8. To what extent do the nutrients, through biological productivity, influence the diel variations in DO and pH?

Larger diel DO and pH fluctuations appear to be associated with higher concentrations of nitrate. This does not, however, apply to sampling sites immediately below Ashland Creek (sites 102 and 108). These two sites appear to have more nitrogen available than needed, but they lack an adequate in-stream substrate to allow the growth of periphyton.

9. Do the diel variations of DO and pH have a measurable effect on fish or aquatic organisms?

No measurable effect on the aquatic organisms was detected in the data as a result of diel fluctuations in DO and pH. The methods of in situ measurement, however, are not necessarily sensitive enough to detect all effects on aquatic organisms.

10. Does the rise in temperature of irrigation water following diversion cause a significant problem for aquatic life?

No measurable effect on the aquatic organisms was detected in the data as a result of high temperatures in Bear Creek. The methods of in situ measurement, however, are not necessarily sensitive enough to detect all effects on aquatic organisms.

33 BACKGROUND

Basin Description

Bear Creek basin, about 30 mi in length, is one of many subbasins in the Rogue River drainage (fig. 12). Bear Creek flows into the Rogue River 126.8 river miles upstream from the mouth of the Rogue. The 362-square-mile drain age basin of Bear Creek has narrow mountain canyons at the upper end and is situated at the junction of the Cascade Range to the east and the Siskiyou Mountains to the southwest. The basin widens to an 8-mile delta near the confluence of Bear Creek and the Rogue River. Bear Creek begins at the con fluence of Emigrant and Neil Creeks, near the city of Ashland.

The black soils of the area resulted from the fluvial erosion and depo sition processes that formed the alluvial valley plain (Latham, 1963). Soils in the study area vary from montmorillonitic clay to granitic sandy material (Pugsley, 1972).

The climate of the basin is moderate, with moist, cool winters and, except for occasional thunderstorms, warm, dry summers. The Siskiyou Moun tains cast a rain shadow over the basin. Average annual precipitation at Medford is about 18 in.; in the higher mountains it is 40 in. or more. Most of the precipitation occurs in the fall and winter months.

Hydrologic System

Irrigation is a requirement for agriculture in the Bear Creek basin and provides much of the streamflow in late summer and early fall as a result of stored reservoir water. Current private water rights in Bear Creek basin total about 120 ft^/s--87.2 percent for irrigation of 8,200 acres, 6.8 percent for power, 2.6 percent for mining, 2.4 percent for municipal uses, and 1 percent for other uses.

To ensure a supply of water for irrigation, approximately 80,000 acre-ft of water is diverted annually from the Klamath Basin into Bear Creek basin. Fourmile Lake, Howard Prairie Lake, and Hyatt Reservoir store water which is delivered to the Bear Creek basin during the irrigation season via a series of canals and natural drainageways (see fig. 1). This water enters the basin from two points: (1) Medford Irrigation District (MID) Canal via Bradshaw Drop and (2) Green Springs diversion from Howard Prairie Reservoir to Emigrant Creek and Emigrant Reservoir above Ashland. Water is also diverted from the Little Applegate Basin via McDonald Canal to Wagner Creek and Fredrick Lateral, Table 4 shows the capacity and date of completion of the reservoirs and the irrigation districts using the stored water. The three districts serve more than 7,400 farms, with 34,500 acres under irrigation (less than 5 acres per

37 /*' - ; - ^-;;t^.;.i>._^.<...|vv.v,v*TI^.~^-^L=-=--i_j------~- I T/' M- I rf v ' : -*' ' K. ,t!,i#-- re---x : >/ r" "^r^ <^

U1T C"; /f:^;:^-::!,'*, '^ &?!-)/\

INDEX MAP OF OREGON

- ;; ....; i V

Bate from U. S. Geological Survey, Oregon (State), 1966.

10 20 30 KILOMETERS

Figure 12. Location of study area in Rogue River basin, Oregon. average farm). These three districts use about 94,000 acre-ft of water annually. The large number of farm units and their small size make the dis tribution system for the irrigation districts complex.

Table 4.--Source of stored water for irrigation districts

[From Rogue Valley Council of Governments (1976) and Don Walker, Bureau of Reclamation (oral commun., March 1978]

Approximate usable capa Date city at maxi com mum pool Reservoir pleted (acre-feet) Irrigation district served

Fourmile Lake 1923 15,650 Rogue River Valley and Medford Fish Lake 1924 8,020 Do. Agate 1966 4,670 Do. Howard Prairie 1958 60,000 Talent. Hyatt 1922 16,180 Do. Emigrant 1924 6,000 Do. Emigrant, 1961 39,000 Do. enlarged

Past Investigations

In an effort to determine water-quality conditions and problems, water- quality samples have been collected since 1960 from Bear Creek and many of its tributaries. In 1960 and 1962, the Oregon State Sanitary Authority measured Bear Creek water quality. Although this study was not intensive, it indicated that the quality of water was unsuitable for most of the desired uses in Bear Creek. In a report by the U.S. Public Health Service (1965), it was concluded that, because of increases in population and industrialization, Bear Creek would need more flow to prevent further degradation of its water quality.

The U.S. Bureau of Reclamation (1966) published a report proposing to enhance flows in Bear Creek during periods of low flow and to provide addi tional water for irrigation districts during the irrigation season. The pro posal included the construction of two dams--one at Lost Creek on the Rogue River and the other on Elk Creek. Water was to be diverted from these impound ments to enhance the quality of water in Bear Creek.

A report by the Soil Conservation Service (Latham, 1963) indicated a need for correction of poor drainage caused by the clay soils. The report recom mended an improvement in irrigation techniques and mentioned the possibility of contamination of shallow wells as urbanization continued in the valley (Latham, 1963).

A study of the biological, chemical, and physical characteristics of Bear Creek in the 1968-69 period by Linn (no date) showed the following:

39 (1) The addition of Ashland Creek water tended to reduce the turbidity of Bear Creek and storm-water runoff in Medford tended to increase it, and (2) sewage-treatment-plant effluent was a source of high nitrate and orthophosphate concentrations in Bear Creek below Ashland Creek.

The U.S. Bureau of Reclamation (Pugsley, 1972) studied Emigrant Reser voir, known to be a source of turbidity for Bear Creek. Montmorillonitic clay and amorphous material that are exposed to wave action on the reservoir banks were found to be responsible for the turbidity.

Water-quality data collected by RVCOG during the 1976 water year showed the following: (1) Violation of dissolved oxygen, pH, and fecal coliform standards; (2) stream temperatures in excess of levels recommended by the Oregon Department of Fish and Wildlife for the protection of fish species; and (3) severe limitation of water use because of suspended-sediment concen trations in Ashland and Bear Creeks during the flushing of Reeder Reservoir (La Riviere, no date).

IRRIGATION-WATER ASSESSMENT

On-Farm Use

Comparison of inflow and outflow sample data shows the change in water quality resulting from irrigation of farm plots. Water samples were collected from pastures, orchards, and row crops, the three major uses of agricultural land in Bear Creek valley. Each inflow and outflow site was sampled at least once. The variability in the quality of water at each of these sampling sites is not known, but it is suspected to be significant, especially at the outflow sites. Rather than using data from a specific site, all the constituent data for each land use were considered when identifying sources or sinks and diluters or concentrators. See page 11 of the Executive Summary or the Glossary for definitions of the terms "source," "sink," "diluter," and "concentrator."

Pastures

Table 5 shows the ratio of outflow to inflow for concentrations and loads of various water-quality characteristics from pastures. Table 6 shows inflow and outflow values and other water-quality characteristics. The data were taken from table 7 of a report by Wittenberg and McKenzie (1978).

Indicator bacteria ratios show that pastures are often a source of bac terial contamination in irrigation-return flows. Increases of fecal coliform in both concentration and load are shown in figure 14. Eleven of 13 outflow samples contained concentrations of fecal coliform approaching or exceeding 1,000 bacteria/100 mL, compared to six of 13 inflow samples.

Suspended-sediment data show a decrease in concentration in nine of 13 pastures. The ground cover of the pastures reduces the velocity and energy of the water and allows the sediment to settle out. As shown in table 6, turbidity values show the same trend as suspended-sediment concentrations.

-40 Table 5,--Ratio of outflow to inflow samples for selected water-quality characteristics from pastures [Locations of sites shown on plate 1]

Indicator bacteria Total Fecal Fecal Suspended Dissolved Kjeldahl Dissolved coliform streptococci sediment nitrate nitrogen orthophosphate Dis Concen Concen Concen Concen Concen Concen Site charge tration Load tration Load tration Load tration Load tration Load tration Load

50 0.37 4.0 1.5 1.7 0.63 0.19 0.07 2.0 0.74 -- -- 0.80 0.30

51 -- 1.2 -- 6.5 -- .32 -- .17 -- 0.75 ------

54 -- .34 -- 5.0 -- .12 -- .43 -- 1.8 -- 1.0 --

55 -- >2.8 -- .46 -- 4.3 -- .06 -- .68 -- 1.9 --

61 .17 >16 >2.7 >5.0 >8.7 .87 .15 .33 .06 8.8 1.5 -- --

70 .10 16 1.6 180 18 .70 .07 -- -- 3.9 .39 3.0 .30

73 1.00 18 18 23 23 .37 .37 -- -- 3.0 3.0 10 10

74 .0057 >1.7 >.01 -- -- 41 .23 .27 .002 -- -- 1.2 .007

78 -- 1.7 -- 2.4 -- 2.0 -- .26 -- 3.0 -- .42 --

79 -- 6.2 -- 12 -- 8.4 -- .39 ------.79 --

81 .05 .76 .038 3.4 .17 .08 .004 .13 .006 -- -- .67 .03

82 .13 15 2.0 8.4 1.1 .37 .048 .14 .02 1.6 .20 2.5 .33

83 .25 1.2 .30 14 3.5 .12 .03 .33 .08 2.4 .59 3.0 .75 Table 6.--Inflow and outflow values for selected water-quality characteristics from pastures

[Locations of sites shown on plate 1]

Dissolved Specific oxygen conductance Temperature (percent pH (umhos/cm Turbidity CO saturation) (units) at 25°C) (Jtu) Site Inflow Outflow Inflow Outflow Inflow Outflow Inflow Outflow Inflow Outflow

50 16 21 97 75 8.2 7.6 180 200 25 2

51 16 21 100 88 7.9 7.6 145 142 25 6

54 15.5 16 96 80 8.0 7.5 240 315 10 5

55 14 14 94 86 7.6 7.3 280 175 50 15

61 15.5 15.5 96 81 8.0 7.7 118 126 25 20

70 16 17.5 134 91 9.2 7.8 148 155 25 10

73 15 15 94 78 8.3 7.4 120 124 30 8

74 17 24 92 -- 6.9 -- 88 124 15 95

78 17.5 16 110 65 7.6 7.3 265 275 6 4

79 18.5 -- 92 -- 7.2 6.9 270 360 7 4

81 16.5 16.5 88 75 6.6 7.5 280 280 25 4

82 16 25 97 84 7.9 7.9 235 230 15 2

83 19.5 18 105 87 8.0 7.0 104 175 25 2 Nitrate data show that 10 of 11 pasture outflows contained concentrations less than did the inflows. All load values computed indicate that pastures act as sinks for this constituent. Uptake of this form of nitrogen by plants is probably the reason for the decrease in concentration. The increase shown in organic (Kjeldahl) nitrogen levels is probably due to decaying organic matter, both vegetation and fecal material, in the pastures.

Orthophosphate load data suggest that pastures act as sinks. However, data from six of 11 sets of samples show increased concentrations of orthophosphate in the outflows.

Table 6 shows variations in temperature; the significance of the vari ations has not been determined. No significant changes are detected from the data on pH or specific conductance. Dissolved-oxygen saturation levels were below 90 percent in 10 of 11 outflow samples. The probable cause of the low dissolved-oxygen saturation levels is decaying organic matter.

Cultivated Orchards

Tables 7 and 8 present ratios and values, respectively, of water-quality characteristics for cultivated orchards. Pastures were shown to be sources of bacteria, whereas orchards act as sinks, as shown in figure 13. Both, how ever, are often concentrators of indicator bacteria. Cultivated orchards con tribute more suspended sediment, turbidity, nitrate, and orthophosphate than do pastures.

Suspended-sediment concentration ratios show that cultivated orchards generally tend to increase the concentration of suspended sediment in water sampled from canals and return-flow streams; but only four of nine outflow samples contained loads greater than did the inflow samples. Soil condition, slope, application method, and discharge affect the amount of sediment in the outflow water. Turbidity data follow the same trend as data for suspended- sediment concentration.

Nitrate ratios in figure 13 show that orchards are generally concentrators

Orchards are generally sinks for orthophosphate. The concentration ratios indicate little or no change in 11 of 17 orchards sampled.

Water temperatures generally increased, as indicated in table 8. Little or no significant change was observed in pH, DO, and specific conductance.

43 Table 7. --Ratio of outflow to inflow samples for selected water-quality characteristics from culti vated orchards

[Locations of sites shown on plate 1] Indicator bacteria Fecal Fecal Suspended Dissolved Dissolved coliform streptococci sediment nitrate or thopho sphate Dis Concen Concen Concen Concen Concen Site charge tration Load tration Load tration Load tration Load tration Load 52 0.19 0.25 0.048 0.33 0.063 1.0 0.19 8.2 1.6 13 2.5 53 .41 2.6 1.1 2.0 .82 .11 .047 1.9 .78 2.5 1.0 56 1.2 .92 1.1 10 12 75 90 14 17 1.8 2.2

57 _ _ .92 _ _ 1.2 _ _ 58 _ _ .15 _ _ 1.2 _ _ 58 .27 1.6 .43 <5.6 <1.5 100 27 6.9 1.9 1.8 .49 59 -- 2.9 -- 1.0 -- 40 -- 2.1 -- 1.2 -- 60 .037 1.0 .037 .10 .026 .066 .0024 30 1.1 2.8 .10 62 -- 3.3 -- 4.7 -- 2.8 __ 1.8 -- .62 -- 63 -- 2.8 -- 1.1 -- 1.8 -- 4.2 -- 1.6 --

64 .13 3.6 .47 .92 .12 17 2.2 8.1 1.0 1.2 .16 65 -- 2.1 -- 7.6 -- 2.7 -- 2.2 -- .35 -- 66 -- 6.5 -- > 12 -- 2.3 -- 7.4 -- 3.0 --

67 .054 12 .65 _ _ _ _ 5.7 .31 9.8 .53 .62 .03 68 .56 .85 .48 1.9 1.1 3.3 1.8 5.9 3.3 .90 .50 69 -- .44 ------12 -- 7.2 -- 1.1 --

72 _ _ 21 _ _ 4.5 _ _ 1.5 _ _ 1.5 _ _ .58 _ _ 75 .26 2.9 .75 4.5 1.2 1.1 .29 1.4 .36 .68 .18 Table 8.--Inflow and outflow values for selected water-quality characteristics from cultivated orchards

[Locations of sites shown on plate 1]

Dissolved Specific oxygen conductance Temperature (percent pH (umhos/cm Turbidity (°C) saturation) (units) at 25°C) (Jtu) Site Inflow Outflow Inflow Outflow Inflow Outflow Inflow 1 Outflow Inflow Outflow

52 ______7.0 7.0 200 165 9 15 53 16 15 89 66 7.5 7.2 200 215 25 10 56 ------205 200 10 35

57 17 18 103 104 7.1 7.0 200 220 30 750 58 16.5 19 102 99 7.8 7.7 157 190 10 400 59 23 32 87 93 7.4 7.2 200 196 10 25 4> Ln 60 18 21 104 100 7.3 7.1 205 360 140 20 62 17 -- 110 -- 7.3 7.1 260 260 15 25 63 15 17 98 92 8.0 7.5 235 240 15 25

64 15.5 17 99 92 8.1 7.5 235 270 10 40 65 20 25 -- 97 -- -- 260 168 10 25 66 20 18 106 86 8.1 -- 180 146 10 35

67 18 23.5 ______68 20 26 97 61 8.0 7.1 260 295 35 35 69 12 25.5 91 92 8.0 7.8 250 270 20 70

72 17 _ _ 103 _ _ 8.1 7.6 290 280 10 15 75 17 19 99 84 8.2 7.1 280 250 20 10 18

16 EXPLANATION Concentration (solid line) 14 Concentrator

12 Dilu'ter

Load (dashed line) ± 2 10 Source Sink si 6 QC ill CO 1 4 Z

4> ON

Orchards

10 Pastures

Pastures 12 FECAL COLIFORM SUSPENDED SEDIMENT DISSOLVED NITRATE

Figure 13. Number of outflow/inflow ratios (for individual farms) showing concentrators, diluters, sources, and sinks for fecal coliform, suspended seditnent, and dissolved nitrate fn pastures and orchards. Row Crops

Row crops sampled include two beet-seed fields and one grass-seed field. The beet-seed fields were adjoining, and the irrigation-return flow from one field provided a part of the inflow for the second field. The beet-seed fields had not been irrigated for 6 weeks prior to sampling, and the beet seed had been harvested 4 weeks prior to sampling. Therefore, it is possible that the large number of bacteria in the samples (see table 9) could result from a first-flush phenomenon explained by Alley (1977). The beet-seed field acted as a concentrator for suspended sediment and orthophosphate and as a sink for nitrate. Table 10 shows a significant decrease in dissolved oxygen and an increase in specific conductance from inflow to outflow in the beet-seed fields.

The grass-seed field had been harvested and part of the field burned prior to sampling. The field acted as a sink for indicator bacteria, sus pended sediment, and nitrate. This is consistent with the finding for pastures. Orthophosphate concentrations increased, and the dissolved oxygen was below 90 percent saturation.

Analysis of data from tables 5 and 7 indicates that there is a weak re lationship between discharge and loading. In general, the lower the discharge ratio, the lower the load ratio. This suggests that if outflow from the irri gated plot is kept to a minimum, the amount of material leaving the plot will also be reduced.

Irrigation-Canal-and-Stream System

The irrigation distribution system is quite complex, as seen in figure 2. The irrigation district discussions, therefore, include a sketch of each irri gation district showing sampling points. Samples were taken on a monthly basis during the 1976 irrigation season. Median values for water-quality char acteristics are listed in table 11. These values are from a report by McKenzie and Wittenberg (1977).

47 Table 9.--Ratio of outflow to inflow samples for selected water-quality characteristics from row crops

[Locations of sites shown on plate 1]

Indicator bacteria Fecal Fecal Suspended Dissolved Dissolved coliform streptococci sediment nitrate orthophosphate Dis Concen Concen Concen Concen Concen Land use Site charge tration Load tration Load tration Load tration Load tration Load

Beet-seed 76 0.13 >23 >3.0 >17 >2.2 14 1.8 3.0 0.39 1.7 0.22 field

Do. 77 .39 ------1.7 .66 .05 .02 4.5 1.8

Grass-seed 80 .78 .54 .42 .89 .70 .41 .32 .34 .27 2.4 1.9 field

00 Table 10.--Inflow and outflow values for selected water-quality characteristics from row crops

[Locations of sites shown on plate 1]

Dissolved Specific oxygen conductance Temperature (percent pH (umhos/cm Turbidity saturation) (units) at 25°C) (Jtu) Land use Site Inflow Outflow Inflow Outflow Inflow Outflow Inflow Outflow Inflow Outflow

Beet-seed 76 17 17 95 38 8.0 7.3 260 400 8 10 field

Do. 77 17 17 60 20 7.4 7.0 390 600 10 15

Grass-seed 80 15 15 91 76 7.6 7.4 305 350 9 5 field Table 11. -Median values of water-quality characteristics in irrigation waters of canals and streams [Locations of sites shown on plate 1]

^ z o § 73 -p C T. ~- C 5 c U 0 m" " S, 5 T3 l T3 a ~O 5 Fecal Fecal Site SJ 'c °- j £ o 5 5 T3 g coliform streptococci T3 *- >% 0-f o O =4 0 Z ?-! c 5 C^ > J > U > CL C R o-Sfc 1 § .£ ||r Irrigation I £ .S2 O. 5^ 2 £ % S Q E 3 on ~" 8.1 Q~ District No. Name 5 H CL H on ° a " B ° % Colonies/100 ml

Talent 1 Ashland Lateral near Ashland 26 15.5 102 7.9 6 13 82 61 0.09 0.01 10 80 Do. 2 Ashland Lateral near downstream end .83 20.0 108 8.2 6 9 85 61 .01 .02 68 320 Do. 3 East Lateral at Emigrant Gap near Ashland 136 15.5 10 7.4 12 8 117 83 .12 .02 <3 < 4 Do. 4 Meyer Creek at South Valley View Road 1.48 16.5 99 7.9 9 19 298 214 .25 .04 1,100 2,800 Do. 5 East Lateral near downstream end at Barnett Road 7.48 20.0 113 8.5 22 34 125 76 .04 .02 210 480 Do. 6 West Lateral at Wagner Creek 26.6 16.5 105 7.9 21 42 117 76 .06 .03 210 120 Do. 7 Talent Lateral near Ashland 31 18.5 112 7.9 11 14 185 118 .06 .05 640 2,300 Do. 8 Lower East Lateral near downstream end at Suncrest Road 2.14 18.5 97 7.7 13 14 239 185 .57 .14 3,400 7,400 Do. 9 Talent Lateral near down stream end at Knowles Road 1.0 21.5 115 8.0 16 28 178 119 .04 .03 290 2,000

Medford 10 Medford Irrigation District Canal at Bradshaw Drop 44 16.5 111 7.8 6 28 72 66 .04 .04 440 550 Do. 1 1 Medford Irrigation District Canal at Fern Valley Road 27.4 19.0 108 7.8 22 42 128 95 .03 .04 600 1,600 Do. 1 2 Payne Creek at Fern Valley Road and Medford Irrigation District Canal 1.56 17.0 96 7.8 27 86 215 124 .18 .04 2,400 2,900 Do. 13 Phoenix Canal at Talent 30 19.0 104 8.0 11 38 212 152 .58 .24 330 920 Do. 14 Phoenix Canal upstream from Griffin Creek 33.6 16.0 103 7.8 18 51 236 145 .67 .20 1,100 980 Do. 15 Phoenix Canal downstream from Griffin Creek 33.5 16.0 99 7.7 16 40 222 132 .61 .18 920 1,200 Do. 16 Phoenix Canal at Jackson Creek 20.2 18.5 105 8.0 16 39 208 134 .54 .15 700 1,000 Do. 17 Phoenix Canal at Old Military Road 3.18 16.0 103 7.9 21 34 215 128 .35 .14 840 1,500

Rogue River Valley 1 8 Rogue River Valley Canal at Bradshaw Drop near Brownsboro 17 16.5 111 7.8 6 28 72 66 .04 .04 440 550 Do. 19 Dry Creek downstream from Agate Reservoir 25.5 19.5 93 8.0 8 11 114 89 .04 .04 6 20 Do. 20 Hopkins Canal upstream from Lone Pine Creek 1.76 16.5 106 7.9 28 41 134 101 .05 .06 740 4,200 Do. 21 Lone Pine Creek near Crater Lake Avenue, Medford 9.51 11.5 101 7.6 6 8 110 90 .02 .08 260 330 Do. 22 Hopkins Canal at Johnson Street 2.41 15.0 110 7.7 8 18 106 86 .02 .10 170 250 Do. 23 Whetstone Creek at Kirtland Road 1.28 21.0 114 8.3 6 9 177 139 .02 .06 160 260 Do. 24 Bear Creek Canal at Medford 25 21.5 125 8.5 8 29 236 156 .44 .18 980 2,000 Do. 25 Hopkins Canal at Scenic Avenue 5.05 19.0 88 7.6 13 40 220 158 .44 .13 610 1,200

\J In micrornhos per centimeter at 25° C.

49 \

122 6ff 122 401

42 20-

Site number from table 11

Natural drainage system

Irrigation distribution system

- 42 10'

Figure 14.-Talent Irrigation District.

Talent Irrigation District

The upper end of Bear Creek basin is served by the Talent Irrigation District canals (fig. 14). The Ashland Lateral, the highest canal in the basin, has the best water quality. Little or no return flow enters the canal. One pH measurement exceeded the State standard in late September, when the pH standard also was exceeded in other canals. Temperatures of 20°C or above occurred on three occasions. Indicator-bacteria concentrations did not exceed the reference level or State standard but did show an increase in a downstream direction.

The water at a downstream site in the East Lateral, site 5, contained concentrations of indicator bacteria greater than those determined for the upstream site, site 3. No exceedance of State standards for fecal coliform occurred in the canal. The pH values were 8.5 or greater on three visits.

50 These high readings were taken during summer and occurred when DO concentra tions were at more than 100 percent saturation, indicating that photosynthetic activity was taking place in the canal. On more than one occasion, samples taken from site 5 had suspended-sediment concentrations and turbidities exceeding reference levels. Canal-bank erosion and channel scour is a possible source.

Water in the Talent Lateral at site 9 and in the Lower East Lateral at site 8 is diverted from Bear Creek at site 7, Oak Street Diversion. Bear Creek above the diversion receives irrigation-return flow from Ashland and East Laterals. Fecal coliform concentrations exceeded the State standard five of a total of 13 times sampled at sites 7, 8, and 9. Also, fecal streptococci concentrations exceeded the reference level on several occasions at all three sites. Suspended-sediment concentrations at site 8 and 9 were above reference levels five of 13 times sampled. Samples from site 8 on the Lower East Lateral had concentrations of nitrate and orthophosphate greater than that found in the water at site 7. The water in this canal is of poorer quality than the water in Ashland, East, and West Laterals. The presence of irrigation-return flow in the Talent and Lower East Laterals is, in part, responsible for the poorer quality of water in these two canals. Meyer and Payne Creeks contain irrigation-return flow from irrigated plots being supplied by the East Lateral. Both Meyer Creek, site 4, and Payne Creek, site 12, contained concentrations of indicator bacteria higher than the State standard eight of 12 times and reference level six of nine times sampled, respectively. The bacteria probably originated from outflows of irrigated plots, failing septic systems, and wild animals.

Suspended-sediment concentrations and turbidity values each exceeded reference levels in Payne Creek five of six times sampled. The suspended sed iment is believed to come from irrigated plots and from the East Lateral. Nitrate concentrations in the irrigation-return flow streams are higher than the concentrations found in the East Lateral. The higher concentrations probably originated from outflows of ground water and from orchards, as indi cated by the data in the on-farm section of this part of the report. Data obtained prior to and after the irrigation season indicate that ground water contributes high concentrations of nitrate. During the irrigation season, the dilute irrigation water tends to reduce the concentration of nitrate.

Medford Irrigation District

The canal data for the Medford Irrigation District (MID) are listed in table 11, sites 10, 11, and 13-17. Canals under MED responsibility are shown in figure 15.

Water temperature, turbidity, and specific conductance, along with con centrations of suspended sediment and indicator bacteria , increased between site 10 and site 11 in a downstream direction. The water in the MED Canal at site 11 contains irrigation-return flow, ground water, and canal water from upstream. The quality of this water is about the same as that of the Talent Lateral.

51 \

122 50" 122 40'

42 25'

EXPLANATION

Site number from table 11

Natural drainage system Irrigation distribution system

MILES

KILOMETERS

Figure 15. Medford Irrigation District.

The Phoenix Canal water is diverted from Bear Creek at the Talent Di version, site 13. Additional water is siphoned across Bear Creek from MID Canal. In the Phoenix Canal, suspended sediment, nitrate, and orthophosphate concentrations are highest of any canal in the basin. The high nitrate and orthophosphate concentrations in the Phoenix Canal are probably the result of sewage-treatment-plant effluent, orchard irrigation outflow, and ground-water seepage.

Analysis of monthly data was made on the Phoenix Canal for suspended sediment, turbidity, nitrate, and orthophosphate. Figure 16 shows the plot for monthly suspended-sediment samples at five sampling sites. The suspended- sediment concentrations were highest during the first 3 months of the irrigation

52 100

O £= 70 < DC !^°I- DC

O DC 0 50

I £40 Q Q Q -1 iu § 30 Q

MAY JUNE JULY AUGUST SEPTEMBER

Figure 16. Suspended-sediment concentrations at selected sites in Phoenix Canal during the 1976 irrigation season.

season and then decreased for the remainder of the irrigation season. Turb idity values followed che same trend as suspended sediment. The higher con centrations of suspended sediment and levels of turbidity in the early part of the season are probably caused by (1) flushing of the irrigation distri bution network of windblown and storm-water material, (2) suspending fine material from freshly tilled fields, and (3) varying the quality of water available for irrigation because of irrigation-return flows from higher ele vations in the basin. The lesser concentrations of suspended sediment in August and September possibly resulted from higher-than-normal precipitation in August that caused reduced irrigation and irrigation-return flow. Figure 17 shows the nitrate concentrations in the samples collected in the early months. As the season progressed, the concentrations increased and then decreased toward the end of the season. The nitrate probably resulted from several sources. These include: (1) sewage-treatment-plant effluent, (2) irrigation-return flow from orchards, (3) ground-water inflow, and (4) re cycling of nutrients from dead algae.

53 Figure 17. Nitrate concentrations at selected sites in Phoenix Canal during the 1976 irrigation season.

Rogue River Valley Irrigation District

Canals operated by the Rogue River Valley Irrigation District (RRVID) are shown in figure 18. The median values for each of the water-quality character istics are listed in table 11.

Median levels of suspended sediment, turbidity, dissolved solids, and indicator bacteria for water samples taken from Hopkins Canal (on the east side of Bear Creek) above Lone Pine Creek, site 20, are larger than those for sites 18 and 19. The larger values are probably caused by irrigation-return flow. Suspended sediment, turbidity, and indicator bacteria values at site 20 each exceeded the reference levels and the State standards two or more times during the 1976 irrigation season.

Lone Pine Creek water samples were of good quality except for one fecal coliform sample that exceeded 1,000 colonies/100 mL. The water in Lone Pine Creek is similar to that in the Ashland Lateral. Most of the water in Lone Pine Creek is overflow from the Medford Aqueduct (see fig. 18). Site 22, downstream from Lone Pine Creek, reflects the introduction of clean water to

54 122 5(T 122 40" I 7

.Canal

17 42 25'

EXPLANATION

Site number from table 11

Natural drainage system

Irrigation distribution system

42 15'

i i 2 6 KILOMETERS

Figure 18. Rogue River Valley Irrigation District.

the canal. The augmentation of flow from Lone Pine Creek into Hopkins Canal reduces the concentrations of various constituents, thereby improving the quality of the water in the canal. The Hopkins Canal (on the west side of Bear Creek) includes water from both the Bear Creek and Hopkins Canals and is siphoned from the east side of Bear Creek. The water diverted from Bear Creek is of poor quality because of use and reuse of water for irrigation, industrial, and domestic purposes. The water is a mixture of irrigation-return flow from the East Lateral, MID Canal, and Phoenix Canal; and point discharge from outflows, such as effluent from a sewage-treatment plant.

55 Half the samples (three of six) of Hopkins Canal water at site 25 did not meet State standards for DO. Fecal coliform concentrations exceeded State standards in one of six samples. Fecal streptococci and suspended-sediment concentrations exceeded reference levels on several occasions. The Hopkins Canal water has about the same quality as that in the Phoenix Canal.

Whetstone Creek

The marsh through which Whetstone Creek flows acts as a biological puri fier. Rooted vegetation acts as a filter and aids in the settling of sus pended sediment and turbidity-causing material. Also, nutrient concentrations in the water are reduced by plant uptake. Although Whetstone, Meyer, and Payne Creeks all contain irrigation-return flow, Whetstone Creek water has lower concentrations of indicator bacteria, dissolved solids, nitrate, and suspended sediment, as well as lower values of turbidity. Irrigation-return flow is responsible for reduced dissolved-solids concentrations in both Whetstone and Meyer Creeks during the irrigation season.

Because of photosynthesis and respiration of water in the marsh, samples often had pH and DO values, respectively, outside the State standard. Water temperatures often exceeded 20°C. Water-quality characteristics of Whetstone Creek are similar to those of the tail water of the Ashland Lateral.

Comparison of Water at Points of Irrigation Diversion and Bear Creek at Kirtland Road

Analysis for each of the water-quality constituents listed in table 12 was made on the basin's irrigation-water supply (inflow) and on water leaving the Bear Creek basin (outflow). The basin's irrigation-supply water includes water that enters Bear Creek basin from the Klamath River basin and natural water of the upper Bear Creek basin. Data for the inflow sites were taken from McKenzie and Wittenberg (1977).

Bear Creek at Kirtland Road was selected to represent basin outflow because most of the water flowing from the basin passes this point. Data for Bear Creek at Kirtland Road, 1976, were taken from La Riviere (no date). Con centrations listed in table 12 are discharge-weighted means for a 5-month period, May-September. Loads were computed from the discharge-weighted mean concentrations. The values for dissolved solids from Bear Creek at Kirtland Road were calculated by using specific-conductance data and the coefficient described on page 109.

56 Table 12.-Quality characteristics of water diverted for irrigation and water leaving the Bear Creek basin, May-September 1976 [Water-quality concentrations are discharge-weighted means]

Site Milligrams per liter

Dis Dissolved Ortho- Fecal Fecal charge Suspended Dissolved nitrate phosphate coliform streptococci No. Name (ft 3 /s) sediment solids as N as P Colonies/ 100 mL

Irrigation diversions

1 Ashland Lateral near Ashland 26 12 54 0.08 0.01 10 75 3 East Lateral at Emigrant Gap near Ashland 115 11 84 .09 .02 8 35 7 Talent Lateral near Ashland 28 18 118 .08 .05 900 1,700 10 Medford Irrigation District Canal at Bradshaw Drop 41 30 68 .06 .05 810 740 18 Rogue River Valley Canal at Bradshaw Drop near Brownsboro 15 32 69 .06 .07 700 1,100 19 Dry Creek downstream from Agate Reservoir 22 9.8 87 .05 .04 20 42

Total diversions 247

Concentration (mg/L) -- 16 81 .08 .03 290 410

Load (tons/d) -- 11 54 .05 .02 i/1.8xl0 1J i/2.5xl0 12

Water leaving Bear Creek basin

106 Bear Creek at Kirtland Road 150 ------

Concentration -- 39 144 .66 .26 1,200 2,200

Load (tons/d) -- 16 58 .27 .11 -/4.40xl0 12 L/8.0xl012

'Colonies per day. Comparison of discharge, bacteria, suspended sediment, dissolved solids, nitrate, and orthophosphate values in irrigation water in the basin with values at Kirtland Road show the following: (1) loads are greater at Kirtland Road, (2) mean discharge at Kirtland Road equals 60 percent of irrigation- water inflows, and (3) discharge-weighted mean concentrations are two to eight times greater at Kirtland Road. The increase in concentration is caused by the use and reuse of the water for irrigation and also by industrial and municipal waste discharge. Sewage-treatment-plant effluent and ground water contribute to flow and loads at Kirtland Road. Similar data for the 1977 ir rigation season were not available. The measured discharge past Kirtland Road in 1977 ranged from 18 to 41 ft^/s. The quality of irrigation water available to the basin in 1977 was about the same as in 1976. Reduced flow past Kirtland Road would tend to reduce the load leaving the basin and would change the values as presented in table 12.

Suspended-sediment concentrations were collected from natural streams and from drains containing irrigation-return flow on the Yakima Indian Reservation in 1975 and 1976. The mean discharge-weighted concentrations for the two streams and seven drains are, respectively, 45 and 129 mg/L (Nelson, 1979). This is considerably more than the 16 and 34 mg/L in Bear Creek basin.

BEAR CREEK AND TRIBUTARIES

This unit of the report brings together all the water-quality data avail able for Bear Creek and its tributaries. Interpretation of the data helped to identify water-quality problems and their causes or sources.

A separate discussion of data at the diel sites is presented for the following reasons:

1. Early in the data-interpretation phase, the authors concluded that monitoring data, collected between 9 a.m. and 4 p.m., should not be included with the diel data collected outside this time period. The reasons for this separation of data are evident in the dissolved- oxygen and pH .discussions on Bear Creek and tributaries.

2. At the diel sites, additional chemical, physical, and biological data were obtained, which allowed more detailed interpretation at these sites.

The diel data are discussed separately following the main discussion on Bear Creek and tributaries.

Initially, the basin was divided into six subareas, each of which included a reach of Bear Creek, as shown in figure 2. These subareas, in downstream order, are called Emigrant, Ashland, Talent, Phoenix, Medford, and Central Point. The boundaries of the subareas parallel the natural drainage channels. In each subarea, at least one diel site is located near the downstream end of the Bear Creek reach. The data were divided into two hydrologic regimens, nonirrigation and irrigation, as explained on page 17. The difference in the water-quality data in the nonirrigation and irrigation

58 regimens indicates the impact of irrigation as well as the natural effects of low flows and high temperatures. Each subarea is discussed separately in this report. Each discussion includes a summary table of median values of selected water-quality constitu ents in samples collected during the two hydrologic regimens. Tables 13 to 18 list the number of samples collected, date of collection, and source of data. Diel data are shown in separate listings: (1) data collected between 9 a.m. and 4 p.m. and (2) data collected over 24 hours.

Data for this analysis were taken from an EPA STORET retrieval made by DEQ in 1978, a Jackson County Department of Planning and Development report (La Riviere, no date), a report from Southern Oregon State College at Ashland (Linn, no date), U.S. Bureau of Reclamation files, Ashland Water Department files, and U.S. Geological Survey Bear Creek data reports (McKenzie and Wittenberg, 1977; Wittenberg and McKenzie, 1978).

Emigrant Subarea of Bear Creek Basin

The Emigrant subarea includes sites extending from Howard Prairie Reser voir to Bear Creek at Interstate 5 (river mile 24.4, as determined by the Columbia Basin Inter-Agency Committee [1967]). Table 13 contains a summary of data collected at 10 stream sites, two canal sites, and one reservoir site. During the nonirrigation regimen, water in Bear Creek at Interstate 5 site consists of (1) Emigrant Reservoir water spilled into Emigrant Creek and (2) Walker Creek and Neil Creek water. During the irrigation regimen, most of the water is diverted from Emigrant Creek into Ashland Lateral above the reservoir or is released from Emigrant Reservoir into the East Lateral and Emigrant Creek. Most of the water spilled from Emigrant Reservoir into Emigrant Creek is diverted into the Lower East and Talent Laterals downstream from Interstate Highway 5 at Oak Street diversion dam. A small volume of irrigation-return flow may be entering Bear Creek from Neil and Walker Creeks.

Interpretation of data for the Emigrant subarea, and summarized in table 13, indicates the following:

1. Median values for dissolved oxygen (DO) show little variation from site to site and from nonirrigation to irrigation regimen; most con centrations range from 110 to 95 percent of saturation. The nondiel data show that in 10 of 78 measurements, the DO was lower than 90 percent saturation (State standard). During the diel study in October 1977, 19 of 41 DO concentrations were less than the State standard.

2. The pH data for Emigrant Creek at Emigrant Road indicate four of seven measurements exceeded the State standard. Bear Creek at Inter state Highway 5 also had four of 10 measurements, and, overall, the Emigrant subarea had 11 of 70 nondiel measurements outside the State standard of 6.5 to 8.5. The diel pH data show no measurements out side the State standards; however, they do indicate a period of high pH between 9 a.m. and 7 p.m., which coincides with the occurrence of high temperature and high DO each day.

59 Table 13. -Water-quality median values for the Emigrant subarea of Bear Creek basin

[Columns adjacent to the DO, pH, and fecal coliform data columns indicate the number of samples that did not meet State standards, and the column adjacent to the fecal streptococci column indicates the number of samples with values greater than 1,000 colonies/100 mL suggested as a reference level. Where the number of measurements differs from the number listed under "Number of samples collected," it is listed a denominator. Fur example, 2/3 means two of three measurements did not meet State standards. DS, downstream]

Specific Total Dissolved ortho- Dissolved conductance Fecal Fecal Dissolved Kjeldahl No. of oxygen (micromhos/ coliform streptococci Suspended nitrate nitrogen phosphate Hydrologic samples Date of (percent PH cm at Turbidity sediment as N asN asP Site 25° C) (Jtu) regimen collected collection saturation) (units) Colonies/ 100 ml (mg/L) Source Howard Prairie Reservoir Irrigation 1 1970 109 0 7.8 0 60 1.0 51OTOIJ UKEl PT . Emigrant Creek at Green Non irrigation 1 1972 . . .. 8 9 -- U.S. Bureau of Reclamation files. Springs Powerplant Irrigation 2 1972 ------11 12 " " ~ " Ashland lateral near diversion Irrigation S 1976 103 0 7.9 0/3 82 10 0 80 0/3 6 13 0.09 0.01 McKenzie and Wittenberg (1977). Emigrant Creek below Non irrigation 1 1972 9 16 U.S. Bureau of Reclamation Tiles. : - -- Sampson Creek Irrigation 2 1972 - - 13 16 Emigrant Creek above Non irrigation 7 1975-76 112 0 7.6 0/6 81 33 0 13 0 6 .21 0.20 .07 La Riviere (no date). Reservoir Irrigation 5 1976 100 0 7.8 0 74 49 0 70 0 7 .14 .40 .12 East lateral at Emigrant Gap below Dam Irrigation 5 1976 105 0 7.4 0/3 117 8 0 35 0/3 12 8 .09 .02 McKenzie and Wittenberg (1977) Emigrant Creek at outlet Non irrigation 11 1972 26 39 U.S. Bureau of Reclamation files. of Reservoir Irrigation 11 1972 - - 29 32 Emigrant Creek at Emigrant Non irrigation 7 1975-76 i!40 0 8.4 3/6 212 33 0 8 1 6 .33 .2 .03 La Riviere (no date). Rd Irrigation 5 1976 107 0 8.0 1 115 5 0 4 0 5 .32 .2 .09 Neil Creek at Highway 66 Non irrigation' 6 1975-76 110 0 7.5 0/5 130 180 0 33 0 4 .42 .2 .07 La Riviere (no date). near mouth Irrigation 6 1976 102 1 7.7 0 47 900 3 1,700 5 7 .13 .5 .16 Neil Creek at Highway 66 Non irrigation 2 1972-74 90 0/1 7.5 1/1 198 <450 0/1 - - _ . 3 .07 STORET. near mouth Irrigation 5 1972-74 98 0/3 7.3 0/3 136 1,200 1/2 - - 15 .16 Emigrant Creek above Non irrigation 1 1972-74 - - 830 - - 18 .02 STORET. Walker Creek confluence Irrigation 3 1972-74 100 0 7.5 0 181 230 ------37 .05 Bear Creek at bridge to Non irrigation 6 1968-69 87 4 8.4 2 . . 15 .16 .11 Linn (no date). Scenic Hills Memorial Irrigation 7 1968-69 88 5 8.4 0 ------24 .16 .10 Park, Ashland Bear Creek at Interstate 5 Non irrigation 6 1975-76 115 0 7.6 1/5 222 110 1 33 0 6 .28 .2 .06 La Riviere (no date). Irrigation 5 1976 109 0 8.6 3 182 460 0 330 0 10 .14 .3 .06 Diel 9:00 a.m.-4:00 p.m. Non irrigation 10 1977 109 0 8.0 0 645 1100/1 2,000 1/1 2 4 .16 .3 .07 Wittenberg and McKenzie (1978). Irrigation 16 1977 100 0 8.2 0 121 1400/2 270 0/2 6 12 .05 .3 .02 Diet all data Non irrigation 41 1977 90 19 /70 .O n\J 665 Wittenberg and McKenzie (1978). Irrigation 63 1977 99 0 7.8 0 122 ------3. Specific-conductance values tend to increase in a downstream di rection, especially below Emigrant Reservoir. During the irrigation regimen, specific-conductance values below the reservoir were lower than during the nonirrigation regimen. Because much of the irri gation water is snowmelt and precipitation that have been stored in Emigrant, Hyatt, and Howard Prairie Reservoirs, this water has low dissolved-solids concentrations and specific-conductance values.

4. Fecal coliform concentrations generally increase in a downstream di rection during the irrigation regimen. This is considered to be the result of greater agricultural and other land-use activity in a downstream direction during the irrigation season. In 1976, the State standard was exceeded in three of 12 samples in Neil Creek and one of 11 in Bear Creek. Overall, the State standard was exceeded in five of 66 samples in the Emigrant subarea.

5. Fecal streptococci median data show the same general trend as fecal coliform data.. Concentrations exceeding 1,000 colonies per 100 mL were measured five times in Neil Creek in 1976 and once each in Bear Creek and Emigrant Creek at Emigrant Road. Emigrant subarea had a total of seven of 56 samples with concentrations above the reference level.

6. Turbidity median values show a definite increase during the irri gation regimen compared to the nonirrigation regimen. Much of the suspended material causing the turbidity downstream from Emigrant Reservoir comes from the reservoir (Pugsley, 1972). Turbidity values were noticeably low in 1977 at the Bear Creek at Interstate Highway 5 diel site, suggesting that low turbidity values correspond with periods of low flow (see fig. 26). Eight of 12 values in table 13 are less than the 15 Jtu reference level.

7. During the irrigation regimen, median concentrations of suspended sediment below Emigrant Reservoir were generally higher than during the nonirrigation regimen. The data, however, do not indicate that Emigrant Reservoir is the source of the material in suspension. Most values in table 13 are less than the 20 mg/L reference level. The low values in 1977 may, in part, result from the unusually low flows in 1977.

8. Median concentrations for dissolved nitrate show a decrease during the irrigation regimen compared to the nonirrigation regimen. Lower concentrations are possibly due to a higher rate of nitrogen uptake by periphyton growth and dilution of base flow by reservoir-water releases during the summer.

Robison (1972) published water-quality data on ground water from wells in the Emigrant subarea, and a review of these data shows the following:

61 \ a. Water in five wells located outside the area under irrigation had a mean nitrate concentration of 0.06 mg/L as N.

b. Water in five wells located within the area under irrigation had a mean nitrate concentration of 0.32 mg/L as N, 5 times the con centration for the wells outside the area under irrigation.

This seems to indicate that ground water within the irrigated area may have a greater concentration of nitrate than water outside the irrigated area, and therefore is a source of nitrate to streams. The source of nitrate in ground water is probably the infiltration of nitrate from manure, fertilizers, and domestic sewage. All concen trations in table 13 are less than the 1.0 mg/L as N reference value.

9. Total Kjeldahl nitrogen median concentrations often show an increase during the irrigation regimen compared to the nonirrigation regimen. This increase coincides with the decrease in nitrate mentioned above and with the nitrogen cycle (p.Ill), indicating an increase in organic nitrogen, possibly as periphyton.

10. Median orthophosphate concentrations often show an increase during the irrigation regimen, but the source of the increase is not known. Data for the laterals and Bear Creek at Interstate Highway 5 show very low concentrations. At other sites, median orthophosphate concen trations exceeded the 0.06 mg/L as P reference value several times.

Ashland Subarea of Bear Creek Basin

The Ashland subarea includes areas that naturally drain into Bear Creek between Interstate Highway 5 bridge (river mile 24.4) and South Valley View Road bridge near Ashland (river mile 19.9). Ashland Creek is an important tributary which carries effluent from a_ sewage-treatment plant. Canals in this subarea include the Ashland, East, West, Lower East, and Talent Laterals.

During the diel studies, sewage-treatment-plant effluent near the mouth of Ashland Creek was sampled several times in June, August, and October 1977. Median water-quantity and water-quality values include: discharge - 1.8 Mgal/d (millions of gallons per day) (2.8 ft^/s), dissolved orthophosphate as P - 8.2 mg/L, dissolved ammonia as N - 20.5 mg/L, dissolved nitrite as N - 1.7 mg/L, dissolved nitrite-plus-nitrate as N - 3.2 mg/L, total Kjeldahl nitrogen as N - 23 mg/L, TOC (total organic carbon) - 19 mg/L, COD (chemical oxygen demand) - 28 mg/L, BODU (ultimate carbonaceous biochemical oxygen demand) - 50 mg/L, specific conductance - 550 micromhos per centimeter at 25°C, and turbidity - 3 Jtu.

A summary of water-quality data for the Ashland subarea as median values, is shown in table 14. These and all other data available for the Ashland subarea show the following:

1. Dissolved-oxygen median concentrations are generally slightly higher than 100 percent saturation. One of two measurements in Butler Creek and one of 32 measurements in Bear Creek at South Valley View Road 62 Table 14. -Water-quality median values for the Ashland subarea of Bear Creek basin

[Columns adjacent to the DO, pH, and fecal coliform data columns indicate the number of samples that did not meet State standards, and the column adjacent to the fecal streptococci column indicates the number of samples with values greater than 1,000 colonies/100 mL suggested as a reference level. Where the number of measurements differs from the number listed under "Number of samples collected," it is listed a denominator. For example, 2/3 means two of three measurements did not meet State standards. DS, downstream]

Specific Total Dissolved Dissolved conductance Fecal Fecal Dissolved Kjeldahl ortho- No. of oxygen (micromhos/ coliform streptococci Suspended nitrate nitrogen phosphate Hydrologic samples Date of (percent PH cm at Turbidity sediment as N as N as P Site regimen collected collection saturation) (units) 25° C) Colonies/ 100 ml (Jtu) (mg/L) Source Ashland Lateral near downstream end Irrigation 5 1976 108 0 8.2 1/3 85 68 0 320 0/3 6 9 0.01 -- 0.02 McKenzie and Wittenberg(1977). Talent Lateral at diversion Irrigation 5 .1976 110 0 7.8 0/4 185 640 2 2,300 2/3 11 14 .06 -- .06 Do. near Ashland Ashland Creek at South Nonirrigation 3 1976-77 100 0 7.9 0 150 3 0 30 0/2 2 1 .06 0.18 .09 Wittenberg and McKenzie(1978). Pioneer Street in Ashland Irrigation 2 1977 100 0 7.6 0 100 4 0 280 0/1 2 3 .04 .28 .06 Ashland Creek at Granite Nonirrigation 32 1975-76 _. .- -- ...... - 8 ------Ashland Water Dept. Street, Ashland irrigation 30 1976 ------5 ------Do. Nonirrigation 14 1977-78 .. .. -- .. -. -. .. 2 ------Do. Irrigation 23 1977 -- .. ------2 ------Ashland Creek at first bridge Nonirrigation 3 1976-77 103 0 7.9 0 260 10 0 46 0/2 1 2 .12 .28 .08 Wittenberg and McKenzie (1 978). upstream from Main St., Irrigation 2 1977 100 0 7.7 0 137 150 0 510 0/1 2 4 .06 .20 .06 Ashland Ashland Creek at Nevada St., Nonirrigation 3 1975-76 114 0 7.5 0 100 330 1 27 0 -- 6 .26 .15 .08 La Riviere (no date). Ashland Irrigation 6 1976 99 0 7.8 0 134 800 3 950 3 -- 10 .21 .15 .10 Do. Nonirrigation 3 1976-77 104 0 7.9 1 270 9 0 46 0/2 1 4 .12 .15 .09 Wittenberg and McKenzie(1978). Irrigation 2 1977 107 0 8.2 0 128 47 0 650 0/1 2 10 .04 .22 .06 Ashland Creek at convert Nonirrigation 31 1975-76 -- - . ------3 ------Ashland Water Dept. tubes near STP Irrigation 30 1976 -- -. ------2 ------Do. Nonirrigation 14 1977-78 -. -- -. -. -. .. 3 ------Do. Irrigation 23 1977 - - _ _ 3 " " " Butler Creek at mouth Nonirrigation 1 1972 81 7.7 0 700 Irrigation 1 1974 99 0 7.7 0 230 0 .- -. ------Bear Creek at Mountain Ave. Irrigation 4 1969-72 101 0 8.1 0 169 420 0 -- .. -- 25 -- -- .04 Do. Diel, 9 am- 4 pm Irrigation 3 1976 104 0 8.5 1 194 ------4 11 .04 .2 .18 McKenzie and Wittenbergd 977). Diel all data Irrigation 11 1976 102 0 82 2 192 Do. Bear Creek at Oak Street Nonirrigation 1 1972 93 0 8.0 0 280 -- 0 .. -. ------STORET. Bridge Irrigation 2 1972-74 98 0 8.1 0 -- 620 0/1 ------" Bear Creek at Ponderosa Nonirrigation 35 1975-76 -- .. -- .. -. -. 6 ------Ashland Water Dept. Packing Irrigation 30 1976 ------10 ------Do. Nonirrigation 20 1977-78 -- -. -- -. -. .. 4 ------Do. Irrigation 23 1977 ------14 ------Bear Creek at South Valley Nonirrigation 6 1968-69 83 4 8.2 0 -- -. -. .. 15 -- .16 -- .11 Linn (no date). View Rd Irrigation 7 1969 % 3 8.4 0 -- .. -- 24 -- .16 .10 Do. Nonirrigation 35 1975-76 -- -- .. ------. -. 8 ------Ashland Water Dept. Irrigation 30 1976 ------10 ------Bear Creek at South Valley Nonirrigation 20 1977-78 -- .- -- -- .. -- -- 4 ------Do. View Rd Irrigation 23 1977 ------14 ------Do. Nonirrigation 3 1975-76 114 0 7.6 0 244 220 1 140 0 -- 12 .24 2.1 .45 La Riviere (no date). Irrigation 5 1976 99 0 8.0 0 195 230 1 330 0 -- 22 .46 1.2 .44 Bear Creek at South Valley Nonirrigation 2 1972-74 84 1/1 7.8 0/1 390 -- 0/1 .. .. -- 9 -- -- 2.7 STORET. View Rd Irrigation 6 1969-74 102 0/5 8.0 0/4 198 620 0/5 ------19 -- -- 2.3 Do. Nonirrigation 3 1976-77 104 0 7.9 0 420 1 3,400 1/2 15 .46 1.7 1.1 Do. Irrigation 2 1977 101 0 7.5 0/1 279 42 0 21 0/1 13 21 2.8 2.0 2.0 Diel, 9 am- 4 pm Nonirrigation 9 1977 101 0 7.9 0 61 0/1 740 0/1 3 10 1.5 5.3 2.1 Wittenberg and McKenzie (1978). Irrigation 17 1977 100 0 8.0 0 195 250 0/2 160 0/2 4 20 .46 1.9 .98 on T> 7.6 0 Diel, all data Nonirrigation 41 1977 U7 ZZ Do. Irrigation 64 1977 93 19 7.9 0 199 ------Diel, 9 am- 4 pm Irrigation 3 1976 99 0 8.1 0 245 20 .43 1.3 3.5 McKenzie and Wittenberg (1977). Diel, all data Irrigation 12 1976 96 0/11 8.0 0 245 ------4 16 .46 1.3 3.2 Do. \

failed to meet the DO State standard of 90-percent saturation. Non- die 1 DO data in Ashland subarea showed 9 of 89 measurements below State standard for DO. Of 116 diel measurements, 41 had low concen trations and occurred at night in Bear Creek at South Valley View Road. Median pH values range from 7.5 to 8.5. Ashland Lateral and Ashland Creek at Nevada Street had 1 measurement each of 5 and 14 measurements, respectively, that exceeded the pH State standard. All the nondiel pH data in the Ashland subarea showed 5 of 84 measurements outside the State standards. Ashland Creek median data show a trend of increas ing pH in a downstream direction during the irrigation regimen. Specific-conductance median values increase in the downstream di rection; there is also a general overall decrease during the irriga tion regimen as compared to the nonirrigation regimen. Sewage- treatment-plant effluent causes some of the increase in specific- conductance values found in the Bear Creek reach in the Ashland subarea. The general decrease during the irrigation regimen is a result of a lower concentration of dissolved solids in water coming from Emigrant Reservoir and Ashland Lateral (table 13). During the nonirrigation regimen, Emigrant Reservoir and Ashland Lateral seldom contribute water to Bear Creek. Comparison of 1976 water year data with 1977 water year data for Ashland Creek at Nevada Street and Bear Creek at South Valley View Road shows higher specific-conductance values during the 1976-77 nonirrigation regimen than during the 1975-76 nonirrigation regimen. To a lesser extent, the 1977 irriga tion regimen had higher specific-conductance values than the 1976 irri gation regimen. This is believed to be the result of the low precipi tation and resultant low streamflow during the 1977 water year. Median fecal coliform concentrations for Ashland Creek show an increas ing trend in a downstream direction and higher concentrations during the irrigation regimen compared to the nonirrigation regimen. The waters from Bear Creek at Mountain Avenue, Bear Creek at Oak Street, and Talent Lateral have the same high concentrations because they have common sources. Concentrations decreased at the South Valley View Road site. Although a chlorine residual was never measured at this site, it is possible that residual chlorine from sewage-treatment plant effluent may have killed many bacteria that otherwise would have been in the creek. Fecal coliform concentrations were also noticeably lower during the 1977 water year than during the 1976 water year, co inciding with low streamflows. Fecal coliform concentrations exceeded State standards in the Ashland subarea as follows: 4 samples from Ashland Creek at Nevada Street, 2 samples from the Talent Lateral, and 3 samples from Bear Creek at South Valley View Road, totaling 9 of 63 samples for the whole Ashland subarea. Fecal streptococci data show about the same general trend as do the fecal coliform data. Concentrations exceeded 1,000 colonies/100 mL 2 times in the Talent Lateral, 3 times in Ashland Creek at Nevada Street, and 1 time in Bear Creek at South Valley View Road, totaling 6 of 38 measurements.

64 6. Median turbidity values show a small but consistent trend of higher values during the irrigation regimen compared to the nonirrigation regimen and in a downstream direction. The two median values from canal sites are among the highest listed (table 14). The trend of increasing turbidities in a downstream direction is similar to that in the Emigrant subarea. During the irrigation regimen, with 17 measurements, only one median value was greater than the 15 Jtu ref erence value.

7. Median suspended-sediment concentrations in table 14 show (a) an in crease during the irrigation regimen compared to the nonirrigation regimen and (b) an increase in a downstream direction for Ashland Creek. Median suspended-sediment concentrations exceeded the 20 mg/L reference level only during the irrigation regimen.

8. Median nitrate concentrations show a definite increase in a down stream direction in both Ashland and Bear Creeks, especially below a sewage-treatment plant. The median concentrations also are less during the irrigation regimen than during the nonirrigation regimen because of dilution of stream water with irrigation water and because of uptake of nitrogen by plants. Nitrate concentrations exceeded the 1.0 mg/L reference level only in Bear Creek below a sewage-treatment plant. This exceedance and the median concentration of nitrate in sewage-treatment-plant effluent identify the effluent as a major source of nitrogen in Bear Creek. Data published by Robison (1972) on water from four wells in the irrigated area of the Ashland subarea show a mean nitrate concentration of 1.5 mg/L as N.

9. Median total Kjeldahl nitrogen concentrations show a definite in crease below a sewage-treatment-plant outfall. They do not show any significant differences between the nonirrigation and irrigation regimens.

10. Median orthophosphate concentrations show an increase at South Valley View Road and no difference in median concentrations between the nonirrigation and irrigation regimens. The median orthophosphate con centrations ranged from 0.02 to 0.18 mg/L in 12 samples collected upstream from the South Valley View Road site. The quadrupling of orthophosphate concentrations downstream from a sewage-treatment plant indicates that the treatment plant is a significant source.

Talent Subarea of Bear Creek Basin

The Talent subarea of the Bear Creek basin includes:

1. The irrigation distribution system, including East, Lower East, Talent, and West Laterals, and the Fredrick Lateral (water diverted from Wagner Creek).

2. Tributaries to Bear Creek, of which Meyer and Wagner Creeks are the most important. Wagner Creek is augmented by water diverted from the Little Applegate watershed.

65 \

3. Bear Creek, extending from South Valley View Road near Ashland (river mile 19.9) to Talent (river mile 17.2). There are no diver sions of creek water into canals in this subarea of Bear Creek.

Median values of water-quality constituents for the Talent subarea are listed in table 15. These and all other available data show the following:

1. None of the 59 nondiel DO measurements was below the State standard, but 52 of 72 diel DO measurements were below the State standard. The reason for the large number of low DO concentrations is discussed in the diel part of this report.

2. The Talent subarea had three of 60 nondiel measurements outside the State standard one in Meyer Creek and two in Wagner Creek.

3. Specific-conductance median values show (a) a definite decrease during the irrigation regimen compared to the nonirrigation regimen, (b) an increase in a downstream direction, and (c) an increase during the 1977 water year for Meyer Creek. In the Talent subarea, lower specific-conductance values often occur in natural creeks when they are used to convey irrigation water to small laterals. For example, table 15 shows the specific conductance of the West and East Laterals to be about equal to that of Meyer Creek during the irrigation regimen. The higher values during the 1977 water year compared to the 1976 water year are a result of low flows in 1977.

4. Fecal coliform concentrations exceeded 1,000 colonies per 100 mL twice in Lower East Lateral, 13 times in Meyer Creek, and five times in Wagner Creek. For the entire Talent subarea, there were 20 con centrations exceeding 1,000 colonies per 100 m/L in 63 samples. The source of the bacteria in Meyer Creek is located between East Lateral and Meyer Creek Road and may be failing septic systems. During the 1976 water year, high concentrations of bacteria were found in Wagner Creek at U.S. Highway 99. During the 1977 water year, neither the Rapp Road nor U.S. Highway 99 site on Wagner Creek had high concen trations of bacteria. The few bacteria found in 1977 suggest that the problem may be related to climatic conditions and possibly to failing septic systems. The data indicated no distinct downstream or seasonal trend.

5. Fecal streptococci concentrations exceeded 1,000 colonies/100 mL two times in the Lower East Lateral, 17 times in Meyer Creek, eight times in Wagner Creek, and one time in Bear Creek, totaling 28 of 51 samples. Again, the source of the bacteria in Meyer Creek appears to be located between East Lateral and Meyer Creek Road. Although Wagner Creek showed high fecal streptococci concentrations at both sites and in different years, there is a trend toward higher counts during the irrigation regimen compared to the nonirrigation regimen, and no trend in a downstream direction.

66 Table 15. - Water-quality median values for the Talent subarea o{ Bear Creek basin

[Columns adjacent to the DO, pH, and fecal coliform data column!, indicate the number of samples that did not meet State standards, and the column adjacent to the iecal streptococci column indicates the number of samples with values greater than 1,000 colonies/100 mL suggested as a reference level. Where the number of measurements differs from the number listed under " Number of samples '-ollected," it is listed as a denominator, l-or example, 2/3 means two of three measurements did no' meet State standards DS, downstream]

Specific Total Dissolved ortho- Dissolved conductance I-ecal fecal Dissolved Kjeldahl No. of oxygen (micromhos/ coliform streptococci Suspended nitrate nitrogen phosphate Hydrologic samples Date of (percent pHr»U cm at Turbidity sediment as N as N as P Site regimen collected collection saturation) (units) 25° C) Colonies/ 100 ml (Jtu) (mg/L) Source

West lateral at Wagner Creek Irrigation 5 1976 108 0 7.9 0/4 117 210 0/4 120 0/4 21 42 0.06 -- 0.03 McKenzie and Wittenberg(1977). East low lateral at Suncrest Rd Irrigation 3 1976 98 0 7.7 0 239 3,400 2 7,400 2/2 13 14 .57 -- .14 McKenzie and Wittenberg( 1977). Meyer Creek at East lateral Nonirrigation 1 1977 96 0 8.3 0 500 70 0 590 0 1 3 .02 0.55 .13 Wittenberg and McKenzie (1978). Irrigation 4 1977 106 0 7.9 0 118 53 0 120 0 18 44 ------Meyer Creek at Meyer Creek Rd Nonirrigation 1 1977 92 0 8.0 0 650 > 2,000 1 1,600 1 2 112 ------Do. Irrigation 4 1977 98 0 7.8 0 305 1,300 3 5,200 4 7 23 ------Meyer Creek at South Valley Nonirrigation 1 1977 97 0 8.0 0 705 1 ,000 0 1,300 1 2 128 .69 -- .06 Do. View Rd Irrigation 5 1977 99 0 7.8 0 330 1,900 3 5,700 5 7 28 .32 -- .07 Do. Nonirrigation 2 1976 116 0 8.2 0 460 840 0/1 100 0 2 22 .34 -- .04 McKenzie and Wittenberg(1977). Irrigation 5 1976 98 0 7.9 0 298 1,100 3 2,800 2/3 9 19 .25 -- .04 Meyer Creek at Interstate 5 Nonirrigation 2 1977 104 0/1 8.6 1 680 700 1 570 0 1 76 .36 .46 .04 Wittenberg and McKenzie(1978). Irrigation 5 1977 100 0/3 8.1 0 450 650 2 2,100 4 2 32 .49 -- .42 Wagner Creek at Rapp Rd Nonirrigation 3 1976-77 100 0 8.1 0 270 160 0 230 0/1 2 1 .35 .20 .09 Do. Irrigation 2 1977 106 0 8.0 1 226 1,100 1 1,600 1/1 20 68 .27 .76 .19 Wagner Creek at U.S. Nonirrigation 3 1976-77 100 0 8.0 0 300 40 0 1,300 1/1 6 10 .65 .25 .10 Do. Highway 99 Irrigation 2 1977 108 0 8.2 1 248 -- 0 1,500 1/1 20 40 .38 .66 .70 Do. Nonirrigation 5 1975-76 110 0 7.3 0/4 254 170 0 94 0 -- 6 .96 .16 .11 La Riviere (no date) Irrigation 5 1976 98 0 8.0 0 294 2,300 4 4,900 4 -- 9 .92 .50 .16 Do. Nonirrigation 2 1972-74 90 0/1 7.5 0/1 295 600 0/1 .. 8 .. .. .07 STOR1T. Irrigation 4 1972-74 100 0/3 7.9 0/3 240 420 0/2 ------30 -- -- .09 Bear Creek at Talent Nonirrigation 8 1977 88 5 7.8 0 527 78 0/2 280 0/1 2 8 2.6 1.60 .98 Wittenberg and McKenzied 978). Diel, 9 am - 4 pm Irrigation 16 1977 98 2 7.8 0 206 230 0/2 950 1/2 -- 200 .6 1.20 .50 Diel .all data Nonirrigation 24 1977 72 21 7.6 0 536 .. -- .. .. -- -- -. -- Do. Irrigation 48 1977 86 31 7.6 0 203 ------\ 6. Median turbidity values showed a trend of higher values during the irrigation regimen compared to the nonirrigation regimen. There was no trend of increasing turbidities in a downstream direction.

7. Except for Meyer Creek, suspended-sediment concentrations generally were higher during the irrigation regimen compared to the nonirri gation regimen, as were turbidity values. The cause of the higher concentrations for Meyer Creek in October, after irrigation was dis continued, is not known. About half the median concentrations for the Talent subarea were greater than the 20 mg/L reference level.

8. Median concentrations for nitrate were lower during the irrigation regimen compared to the nonirrigation regimen. This probably resulted from dilution by irrigation water and from uptake by plants followed by conversion of inorganic nitrogen into an organic state. During the nonirrigation regimen, the Bear Creek site exceeded the 1.0 mg/L as N reference level once.

9. Except in Bear Creek, total Kjeldahl nitrogen concentrations were higher during the irrigation regimen than during the nonirrigation regimen. These higher Kjeldahl nitrogen concentrations coincided with lower concentrations of nitrate, as noted in item 8 above. Two sources of Kjeldahl nitrogen are sewage-treatment-plant effluent, which enters all year, and dislodged periphyton in the canals and streams during the irrigation season. The decrease in Kjeldahl nitro gen concentrations in Bear Creek during the irrigation regimen show the dilution effect of irrigation water to be greater than the pro duction of Kjeldahl nitrogen by periphyton.

10. Except in Bear Creek, median orthophosphate concentrations were greater during the irrigation season than during the nonirrigation season. This increase ranged from 0.03 to 0.96 mg/L compared to the 0.06 mg/L reference level. The median orthophosphate concentrations in Bear Creek were seven to 14 times higher than the reference level; the greatest concentrations were measured in Bear Creek at South Valley View Road. This shows the sewage-treatment-plant effluent to be a major source of orthophosphate to this subarea.

Phoenix Subarea of Bear Creek Basin

The Phoenix subarea (see fig. 2) includes parts of the East Lateral; the Medford Irrigation District (MID) and Phoenix Canals; an irrigation diversion dam on Bear Creek to provide water for the Phoenix Canal near Talent; tribu taries, including Anderson, Coleman, and Larson Creeks; and Bear Creek at Talent (river mile 17.2) to Bear Creek at Barnett Road (river mile 11.0). The MID Canal brings additional water into the basin from Little Butte Creek and augments Bear Creek water diverted into the Phoenix Canal. Because the Phoenix Canal diversion is the first downstream diversion from Ashland Creek, Phoenix Canal contains sewage-treatment-plant effluent and is rich in nutrients.

68 Median values for water-quality parameters for the Phoenix subarea are listed in table 16. These and all other available data show the following:

1. Thirteen of 146 DO measurements showed less than 90 percent sat uration. These low concentrations occurred in Payne Creek at Fern Valley Road, Anderson Creek at U.S. Highway 99, Larson Creek at North Phoenix Road, Larson Creek at Ellendale Road, Bear Creek at Suncrest Road, and Bear Creek at Barnett Road. The causes of these low con centrations are probably oxidation of organic material by bacteria and respiration of algae. Of 87 diel measurements in Bear Creek, 26 were below the State standard for DO.

2. Fifty-nine measurements of pH in this subarea exceeded the State standard's upper limit of 8.5. Twenty-eight of 141 nondiel measure ments made in canals, tributaries to Bear Creek, and Bear Creek, and 31 of 86 diel measurements in Bear Creek were also in excess of the State standard for pH. These data show a trend of increasing pH values in a downstream direction in the tributaries and higher pH values during the irrigation regimen compared to the nonirrigation regimen in Bear Creek. Slightly higher values were measured during the 1977 water year than during the 1976 water year.

3. Of all tributaries studied in the Phoenix subarea, specific-conductance values during the irrigation regimen are about half those during the nonirrigation regimen because of the heavy use made of the natural channels to carry irrigation and drainage water to and from farm plots. Bear Creek also has lower specific-conductance values during the irrigation regimen compared to the nonirrigation regimen. Spe cific conductance was higher during the 1977 water year than during the 1976 water year.

4. Fecal coliform concentrations in the Phoenix subarea exceeded the State standard of 1,000 colonies/100 mL in 31 of 116 measurements. Table 16 shows the sites and number of violations. Fecal coliform data indicate a trend of increasing concentrations in a downstream direction in Coleman Creek. Almost all sites have higher concen trations during the irrigation regimen compared to 'the nonirrigation regimen and fewer bacteria measured during the 1977 water year than during the 1976 water year. One source of fecal coliform appears to be irrigation-return flow, with a mean concentration of 2,700 colonies/ 100 mL for 12 outflows from farm plots in the Phoenix subarea.

5. Fecal streptococci concentrations exceeded the reference level of 1,000 colonies/100 mL in 26 of 89 measurements. The trends are similar to those for fecal coliform. One source of fecal strepto cocci in this subarea is irrigation-return flow, with a mean concen tration of 14,000 colonies/100 mL for 13 outflows from farm plots.

6. Median turbidity values are higher during the irrigation regimen com pared to the nonirrigation regimen. Because the turbidity values for tributaries are higher than those shown for canals, the source is not irrigation supply water and is probably irrigation-return flow

69 f

Table 16.-Water-quality median values for the Phoenix subarea of Bear Creek basin

[Columns adjacent to the DO, pH, and fecal coliform data columns indicate the number of samples that did not meet State standards, and the column adjacent to the fecal streptococci column indicates the number of samples with values greater than 1,000 colonies/100 mL suggested as a reference level. Where the number of measurements differs from the number listed under "Number of samples collected," it is listed a denominator. For example, 2/3 means two of three measurements did not meet State standards. DS, downstream]

Specific Total Dissolved Dissolved conductance Fecal Fecal Dissolved Kjeldahl ortho- No. of oxygen (micromhos/ coliform streptococci Suspended nitrate nitrogen phosphate Hydrologic samples Date of (percent pH cm at Turbidity sediment as N as N as P Site regimen collected collection saturation) (units) 25° C) Colonies/ 100 ml (Jtu) (mg/L) Source 34 0.04 McKenzie and Wittenberg (1977). East lateral at Barnctt Rd. Irrigation 5 1976 113 0 8.5 1 125 210 0 480 0/3 22 -- 0.02 (near downstream end) 42 .03 -- .04 Medford Irrigation District Irrigation 5 1976 108 0 7.8 1 128 600 2 1,600 2/3 22 Do. (MID) Canal at Fern Valley Rd 9 .72 Payne Creek at Fern Valley Nonirrigation 1 1976 89 0 8.2 0 460 1 ,900 1 1,300 1 2 -- .06 McKenzie and Wittenberg(1977). 86 .11 oQ .04 Rd. (MID Canal) Irrigation 5 1976 95 1 7.8 0 215 2,400 4 2,900 3 27 Phoenix Canal at Talent Irrigation 5 1976 105 0 8.0 0/4 212 330 0 920 1/3 11 38 .58 -- .24 McKenzie and Wittenberg(1977). Anderson Creek at U.S. Nonirrigation 1 1976 115 0 8.8 1 433 180 0 33 0 -- 6 .81 0.3 .04 La Riviere (no date). Highway 99 Irrigation 6 1976 93 2 8.0 0 237 740 1 700 2 -- 16 .56 .8 .31 Coleman Creek at Pioneer Rd Nonirrigation 4 1976-77 94 0 8.0 0 405 6 0 310 0/1 1 1 .19 .16 .11 Wittenberg and McKenzie(1978). Irrigation 1 1977 96 0 8.2 0 360 290 0 850 0 15 44 .12 .23 .08 Coleman Creek at Houston Rd Nonirrigation 4 1976-77 94 0 7.5 0 390 27 0 680 0/2 2 2 .46 .26 .10 Do. Irrigation 1 1977 101 0 8.1 0 275 460 0 730 0 30 49 ------Coleman Creek at U.S. Nonirrigation 4 1976-77 104 0 8.2 1 450 220 0/3 1,000 1/2 2 4 .22 .46 .14 Wittenberg and McKen?ie(1978). Highway 99 Irrigation 1 1977 102 0 8.1 0 210 1,900 1 1,800 1 50 98 .58 .35 .14 Do. Nonirrigation 6 1975-76 110 0 8.0 2/5 380 300 0 52 0 -- 4 1.1 .42 .12 La Riviere (no date). Irrigation 5 1977 96 0 8.0 0 217 1,400 4 1,300 3 -- 19 .58 .50 .25 -- Coleman Creek at U.S. Nonirrigation 1 1972 91 0 8.0 0 -- 600 0 .. .. ------STORET -- Highway 99 Irrigation 2 1972-74 104 0 8.0 0 267 2,400 1/1 .- .. ------Larson Creek at North Nonirrigation 2 1976-77 98 1 8.0 0 380 68 0 - . 10 20 .01 .38 .14 Wittenberg and McKcn7ie(1978). Phoenix Rd Irrigation 1 1977 101 0 7.9 0 104 420 0 770 0 60 209 .13 .35 .06 Do. Larson Creek at Kllendale Rd Nonirrigation 4 1976-77 103 0 8.4 1 500 9 0 180 0/2 2 13 .02 .24 .05 Irrigation 1 1977 99 0 8.5 0 190 640 0 940 0 35 46 .07 .36 .10 -- Do. Nonirrigation 6 1975-76 114 0 7.8 0 387 150 1 48 0 10 .28 .70 .08 La Riviere (no date) -- Irrigation 5 1976 98 0 8.0 1 97 4,900 4 3,300 5 34 .12 .06 .14 ------Larson Creek at Ellendale Rd Nonirrigation 1 1972 89 1 8.0 0 650 0 - - -- STORET Irrigation 2 1972-74 92 0 7.8 0 -- 2,400 1/1 -. .. ------Bear Creek at Interstate Nonirrigation 4 1975-76 110 0 7.8 0/3 252 900 2 140 0 -- 13 .50 1.1 .34 La Riviere (no date) 5 near Sancrest Rd. Irrigation 5 1976 101 0 8.1 1 242 790 1 280 1 -- II .64 .6 .41 Bear Creek at Suncrest Rd Diel, 9 am - 4 pm data Irrigation 4 1976 122 0 8.4 1 290 -. -. -- .. 4 8 .84 1.2 1.3 McKenzie and Wittenberg! 1977). Diet, all data Irrigation 10 1976 102 4 8.2 1/9 290 .. .. -. -. ------Do. Bear Creek near Phoenix Irrigation 4 1969-72 116 0 8.7 3 224 420 0/3 .. .. -- 15 -- -- .19 STORF.T. Bear Creek at Glenwood Rd Nonirrigation 4 1975-76 110 0 7.6 0 276 340 0 64 0 _. 8 .48 .40 .19 La Riviere (no date). Irrigation 5 1976 100 0 8.2 1 252 1,100 3 490 1 -- 19 .61 .60 .24 Bear Creek at Barnett Rd Nonirrigation 34 1975-76 ------. .- -. -. 5 ------Ashland Water Dept. Irrigation 30 1976 ------.. -- 11 -' Do. Nonirrigation 20 1 y077 I 1- 78to 4 Do. Irrigation 23 1977 -- -- -. .- -_ -- .- 14 ------Bear Creek at Barnett Rd Nonirrigation 6 1968-69 96 2 8.6 3 -- .. .. -- .. 12 -- 1.0 .46 Linn (no date) Irrigation 7 1969 99 2 8.8 6 ------25 -- .25 -- .40 Bear Creek at Barnett Rd Nonirrigation 4 1972-75 98 0/2 7.8 0/2 370 2,300 -- .. -- 16 -- -- .43 STORET. Irrigation 2 1972-74 116 0 8.2 0 310 7,000 1/1 ------30 -- -- .25 Do. Nonirrigation 4 1975-76 114 0 7.6 0/3 292 200 0 55 0 -- 8 .54 .63 .20 La Riviere (no date). Irrigation 5 1976 111 0 8.6 3 185 2,200 4 2,300 4 -- 34 .37 .70 .20 Do. Nonirrigation 4 1976-77 114 0 8.2 1 400 20 0 140 0/2 6 11 1.1 .75 .71 Do. Irrigation 1 1977 116 0 7.8 0 269 190 0 20 0 20 22 .54 .47 .89 Bear Creek at Barnett Rd. Diel, 9 am - 4 pm data Irrigation 3 1976 137 0 9.1 3 178 -- -- 10 32 .14 .6 .30 Do. 113 1 DO e 10 1 713 Diel, all data Irrigation 9 1976 O.O J/O 1 to Do Diel, 9 am - 4 pm data Nonirrigation 17 1977 136 0 8.6 4 140 0/1 2,700 1/1 2 17 1.9 .6 .62 Wittenberg and McKenzie (1978). Irrigation 17 1977 136 0 8.8 12 290 220 0/2 400 0/2 14 .32 .5 .28 Diel, all data Nonirrigation 25 1977 % f.u 8.0 6 Do. Irrigation 50 1977 91 25 8.3 20 302 - returning via tributaries. Most of the 15 farm plots sampled in the Phoenix subarea are orchards, and they have an average outflow tur bidity of 98 Jtu. Coleman Creek has a trend of increasing turbidity in a downstream direction. The average of the median turbidity values for a nonirrigation regimen was 4 Jtu, whereas the average of the median values for the irrigation regimen was 24 Jtu.

7. Median suspended-sediment concentrations are (a) higher in tribu taries than in Bear Creek, (b) higher in Bear Creek during the irri gation regimen compared to the nonirrigation regimen, and (c) in creasing in the downstream direction of Coleman Creek. These trends are similar to those identified for turbidity. Samples of outflows from 15 farm plots in this subarea have an average suspended-sediment concentration of 740 mg/L. Thus, a source of suspended sediment appears to be irrigation-return flow. Also, like turbidity, suspended-sediment concentrations were generally below the reference level of 20 mg/L during the nonirrigation regimen and above the ref erence level during the irrigation regimen.

8. Median concentrations of nitrate were lower during the irrigation regimen compared to the nonirrigation regimen. Only Larson Creek has low concentrations; the average of the median concentrations at three sites was about 0.11 mg/L as N during the nonirrigation regimen. These low concentrations appear to be the result of the lack of ground-water seepage during the nonirrigation regimen. In 15 outflow samples from irrigated farm plots in this subarea, the average of the median nitrate concentrations was 2.9 mg/L as N. The mean nitrate concentrations for eight wells reported by Robison (1971) is 8.6 mg/L as N. Therefore, the authors concluded that the concentrations listed in table 16 for tributaries and Bear Creek during the irri gation regimen are (a) increased by irrigation-return flows and ground-water drainage (sources) and (b) diluted by canal water. The higher concentrations during the nonirrigation than the irrigation regimen in Bear Creek are caused by sewage-treatment-plant effluent, as they are in the Talent and Ashland subareas. The higher nitrate concentrations during the nonirrigation regimen in most of the trib utaries are believed to be caused by ground-water discharge. How ever, during the nonirrigation regimen, the nitrate concentrations were generally below the reference level of 1.0 mg/L as N, except in Bear Creek.

9. Total Kjeldahl nitrogen median concentrations show a slight increase in tributaries during the irrigation regimen. This probably results from greater productivity of aquatic plants during the irrigation regimen compared to the nonirrigation regimen. The same effect was noted by P. R. Boucher and M. 0. Fretwell (U.S. Geological Survey, written commun., 1978) in Sulphur Creek basin, Washington.

10. Median orthophosphate concentrations generally are higher in tribu taries during the irrigation regimen than during the nonirrigation regimen. One source of orthophosphate is irrigation-return flow. The average orthophosphate concentration from 15 farm-plot samples in

71 V

the Phoenix subarea is 0.25 mg/L as P. Sewage-treatment-plant effluent is a source of orthophosphate in Bear Creek during the nonirrigation regimen and to Phoenix Canal during the irrigation regimen. About 45 percent of the orthophosphate concentrations are one to four times greater than the reference level of 0.06 mg/L as P. Exceptions are East Lateral and MID Canal, which average 0.03 mg/L, and Bear Creek, which has concentrations three to 12 times greater than the reference level.

Medford Subarea of Bear Creek Basin

The Medford subarea includes the main stem of Bear Creek from Barnett Road (river mile 11.0) to Table Rock Road (river mile 6.9) (see fig. 2). Tributary inflow includes Hansen and Crooked Creeks and a log pond draining into Bear Creek near river mile 8. Water in the MID Canal at Bradshaw Drop and Agate Reservoir is conveyed into Bear Creek watershed via the Hopkins Canal. This water, plus water diverted from Bear Creek into the Bear Creek Canal, is siphoned to the west side of Bear Creek and distributed by the Hopkins Canal for irrigation.

A log-pond outflow was sampled several times in June, August, and October 1977 during the diel studies. Median water-quality concentrations in clude dissolved orthophosphate as P, 0.20 mg/L; total ammonia as N, 0.25 mg/L; dissolved nitrite as N, less than 0.02 mg/L; dissolved nitrite-plus-nitrate as N, 0.02 mg/L; total Kjeldahl nitrogen as N, 3.5 mg/L; TOG, 52 mg/L; COD, ,154 mg/L; and BODu, 66 mg/L. Discharge ranged from 10 to 75 gal/min. Turbid ity and suspended-sediment values were about 50 Jtu and 140 mg/L, respectively,

Median values for selected water-quality constituents in the Medford subarea are shown in table 17. These and all other available data show the following:

1. Fifty-five of 203 measurements did not meet the DO State standard. However, median values shown in table 17 are generally greater than 100 percent saturation. Two low concentrations on Dry Creek may be the result of withdrawing water from below a thermocline in Agate Reservoir. Other low DO concentrations occurred in Hansen Creek above Kogap Hill and Crooked Creek at U.S. Highway 99. Further analysis shows that these low DO concentrations were often from measurements made in the morning and during the 1977 water year when natural streamflow was very low (see fig. 26).

The diel data for June 1977 in Bear Creek at Table Rock Road showed a low DO of 31 percent saturation, or 2.6 mg/L. This low DO concen tration occurred when flow was extremely low and during the night. The reasons for this low DO during the diel studies are explained in the diel part of this report.

2. Sixty-five of 197 pH measurements exceeded the State standard's upper limit of 8.5, four occurring in canals, five in tributaries, and 56

72 Table 17. -Water-quality median values for the Medford subarea of Bear Creek basin

a iciereiice icvei. wnere me numoer or measurements uiners irom tne numoer ustea unaer Numoer 01 samples cc denominator. For example, 2/3 means two of three measurements did not meet State standards. DS, downstream]

Specific Total Dissolved Dissolved Kjeldahl oriho- Dissolved conductance Fecal Fecal Suspended nitrate No. of oxygen (micromhos/ nitrogen phosphate coliform streptococci sediment as N as N as P Hydrologic samples Date of (percent PH cm at Turbidity Site regimen collected collection saturation) (units) 25° C) Colonies/ 100 ml (Jtu) (mg/L) Source Rogue River Valley Canal (Hopkins Canal) at Bradshaw Drop Irrigation 5 1976 102 0 7.8 1/4 72 440 1 550 1/3 6 28 0.04 -- 0.04 McKenzie and Wittenberg(1977). Dry Creek below Agate Reservoir Irrigation 5 1976 90 2 8.0 1/4 114 6 0 20 0/3 8 11 .04 -- .04 Do. Hopkins Canal upstream from Lone Pine Creek Irrigation 5 1976 106 1 7.9 1 134 740 2 4,200 1/2 28 41 .05 -- .06 Do. Lone Pine Creek near Crater Nonirrigation 1 1976 104 0 8.1 0 106 < 1 0 <1 0 2 2 .04 -- .10 Do. Lake Ave. upstream of Hopkins Canal Irrigation 5 1976 101 0 7.5 0 110 260 1/4 330 1/4 6 8 .02 -- .08 Hopkins Canal at Johnson St Irrigation 5 1976 107 0 7.7 0 106 170 1 250 1/3 8 18 .02 -- .10 Do. Bear Creek Canal at Medford downstream of Jackson St. Bridge Irrigation 5 1976 125 0 8.5 1/4 236 980 2 2,000 2/3 8 29 .44 -- .18 McKenzie and Wittenberg(1977). Hansen Creek above Kogap Nonirrigation 4 1976-77 89 3 8.0 0 1,000 340 0/3 550 0/2 2 67 2.7 0.42 .04 Wittenberg and McKenzie (1978). Mill Irrigation 1 1977 % 0 7.9 0 215 250 0 1,600 1 35 119 .7 .89 .17 Hansen Creek at U.S. Nonirrigation 4 1976-77 109 1/3 8.1 1 875 250 0/3 200 0/2 5 15 1.3 .40 .08 Do. Highway 99 Irrigation 1 1977 % 0 8.0 0 220 440 0 1,300 1 40 109 .66 .75 .18 Do. Nonirrigation 6 1975-76 112 0 7.6 1/5 668 200 0 120 1 __ 12 1.5 .62 .12 La Riviere (no date). Irrigation 5 1976 116 1 8.6 2 230 740 2 1,800 4 -- 38 .94 .70 .36 Crooked Creek at South Nonirrigation 3 1976-77 99 0 8.0 0 580 1000/2 360 0/2 3 5 .50 .13 .06 Wittenberg and McKenzie (1978). Stage Rd. Irrigation 2 1977 95 0 8.0 0 248 750 1 6,900 1/1 28 48 .05 .66 .09 Crooked Creek at Kings Nonirrigation 3 1976-77 108 0 8.3 1 600 580/2 340 0/2 2 9 .06 .38 .06 Do. Highway Irrigation 2 1977 % 0 8.2 0 242 720 0 3,100 1/1 32 70 .14 .63 .12 Crooked Creek at U.S. Nonirrigation 3 1976-77 88 2 8.0 0 400 730 1/2 3,300 2/2 15 3 .92 .59 .21 Do. Highway 99 Irrigation 2 1977 80 2 7.9 0 279 880 0 4,100 1/1 40 102 .60 2.0 .12 Do. Nonirrigation 6 1975-76 104 0 7.7 0/5 364 4,000 5 1,800 6 -- 12 .85 .5 .10 La Riviere (no date). Irrigation 5 1976 % 1 8.0 0 265 3,300 5 3,300 5 -- 37 .39 .70 .24 Bear Creek at Main St. Bridge at Medford Irrigation 4 1969-72 122 0 8.9 3 238 600 0 __ .. -- 32 -- -- .18 STORET. Bear Creek at Me Andrews Rd. Nonirrigation 4 1975-76 110 0 7.8 0 312 640 1 130 0 -- 11 .52 .77 .24 La Riviere (no date). Irrigation 5 1976 103 0 8.6 3 226 3,100 5 1,300 4 -- 28 .39 .65 .24 Bear Creek at State Highway Nonirrigation 62 Bridge at Medford Irrigation 4 1969-72 128 0 9.0 3 192 230 1/3 __ -. -- 26 -- -- .17 STORET. Bear Creek at State Highway Nonirrigation 5 1968-69 102 1 8.8 4 ,_ __ __ .- 12 __ .25 __ .53 Linn (no date). 62 Bridge at Medford Irrigation 6 1969 112 0 9.1 4 ------28 -- .07 -- .33 Bear Creek at Table Rock Nonirrigation 4 1976-77 110 0 8.2 2 428 68 0 160 0/2 7 10 .70 .64 .52 Wittenberg and McKenzie (1978). Rd Irrigation 1 1977 130 0 8.7 1 243 810 0 380 0 20 44 .24 .68 .47 Bear Creek at Table Rock Nonirrigation 4 1975-76 113 0 7.8 0/3 313 600 1 170 0 -- 13 .64 .8 .26 La Riviere (no date). Rd., all data Irrigation 5 1976 103 0 8.5 3 225 3,300 5 1,100 3 32 .52 .70 .24 Diel, 9 am- 4 pm Irrigation 3 1976 132 0 9.4 3 210 ------10 20 .11 2.0 .34 McKenzie and Wittenberg(1977). Diel, all data Irrigation 11 1 Qlf.7/D 103 0 8.2 3/10 217 McKenzie and Wittenberg(1977). Diel, 9 am - 4 pm data Nonirrigation 8 1977 136 0 8.8 6 514 200 0/1 140 0/1 3 __ .97 .5 .38 Wittenberg and McKenzie (1978). Irrigation 16 1977 150 1 8.7 10 298 320 0/2 420 0/2 12 .04 .8 .28 Diel, all data Nonirrigation 25 1977 89 14 8.4 10 -- -- Wittenberg and McKenzie (1978). Irrigation 48 1977 150 27 8.4 20 in the main stem of Bear Creek. Of the 56 high values in the main stem, 33 were detected during the diel studies.

3. Median specific-conductance values for Hansen and Crooked Creeks show a large decrease during the irrigation regimen, caused by the addi tion of irrigation water lower in dissolved solids. Specific- conductance values for Bear Creek were lower during the irrigation regimen than during the nonirrigation regimen. Specific conductance was generally higher in the 1977 water year than in the 1976 water year because of the lower flows and less irrigation water.

4. Fecal coliform data indicate that 34 of 106 measurements exceeded the State standard. Thirty-one of these high concentrations were detected during the 1975-76 sampling period and only two during the 1977 period. This suggests that low flows may help to control the concentrations of bacteria in streams. One obvious source of fecal coliform during the irrigation regimen is irrigation-return flow, because the average concentration of fecal coliform bacteria from nine farm plots in this subarea is 3,800 colonies/100 mL.

5. Fecal streptococci concentrations exceeded the 1,000 colonies/100 mL reference level in 36 of 80 samples collected in the Medford subarea; 29 exceedances occurred during the 1976 water year and seven in the 1977 water year. These results are similar to those for fecal coli form. The average concentration of fecal streptococci in seven out flows from farm plots is 15,000 colonies/100 mL.

6. Median turbidity values were higher during the irrigation regimen than during the nonirrigation regimen. Hansen and Crooked Creeks show a trend of higher values in a downstream direction. Sources of turbidity in Bear Creek include irrigation-return flow and a log pond. The mean turbidity of water from six outfalls of irrigated farm plots in the Hansen Creek and Crooked Creek drainages is 33 Jtu. Canals during the irrigation regimen and streams during the nonirri gation regimen generally had turbidity values of less than the refer ence level of 15 Jtu, whereas the streams during the irrigation regimen generally had water with turbidities greater than 15 Jtu.

7. Median suspended-sediment concentrations also increased during the irrigation regimen, similar to those for turbidity. Outfalls from 11 irrigated farm plots had a mean suspended-sediment concentration of 110 mg/L. These outfalls and a log pond probably are the major sources of suspended material in Bear Creek. The streams generally had less than the reference level of 20 mg/L of suspended sediment during the nonirrigation regimen, whereas the canals and streams generally had more than 20 mg/L during the irrigation regimen.

8. Median nitrate concentrations were lower during the irrigation regi men than during the nonirrigation regimen, probably due to the following:

74 a. Irrigation water of low nitrate concentration (0.04 mg/L as N) imported into the watershed during the irrigation season.

b. Ground water seeping into the streams year round (eight wells had a mean nitrate concentration of 3.2 mg/L as N [Robison, 1971]).

c. Irrigation-return flow being present during the irrigation season, with an average nitrate concentration of 3.3 mg/L as N for 11 outfall samples from farm plots.

d. The absence of sewage-treatment-plant effluent in this reach of Bear Creek during the irrigation regimen, due to upstream diversion.

e. An increase in biological uptake of nitrate during the warm weather, which coincides with the irrigation season.

Higher nitrate concentrations in streams during winter than during summer were also found by P. R. Boucher and M. 0. Fretwell (U.S. Geo logical Survey, written commun., 1978) for the Sulphur Creek basin in Washington. The nitrate concentrations were all below the reference level of 1.0 mg/L as N except for Hansen Creek during the nonirrigation regimen.

9. Total Kjeldahl nitrogen concentrations generally were higher during the irrigation regimen than during the nonirrigation regimen, sub stantiating the uptake of nitrate by plants. P. R. Boucher and M. 0. Fretwell (U.S. Geological Survey, written commun., 1978) also showed this to be true in irrigation drains in the Sulphur Creek basin in Washington.

10. Median orthophosphate concentrations were higher during the irri gation regimen than during the nonirrigation regimen in Hansen and Crooked Creeks. The mean concentration of 11 outflow samples from irrigated farm plots in the Medford subarea was 0.29 mg/L as P. Most of the Bear Creek sites showed higher orthophosphate concentrations during the nonirrigation regimen than during the irrigation regimen. Part of this increase is due to sewage-treatment-plant effluent. Water in the canals generally had less orthophosphate than the 0.06 mg/L as P reference level, whereas tributaries had one to two times as much and Bear Creek had three to seven times as much.

Central Point Subarea of Bear Creek Basin

The Central Point subarea is in the farthest downstream part of the Bear Creek basin. This subarea also includes the farthest downstream part of the West and Talent Laterals and the Phoenix and Hopkins Canals. It includes Griffin, Jackson, and Willow Creeks, which drain into Bear Creek; and Whetstone Creek, which drains into the Rogue River. Bear and Whetstone Creeks at Kirtland Road include most of the drainage into the Rogue River from Bear Creek watershed. The drainage pattern for this subarea is illustrated in figure 2. 75 \ Median values for selected water-quality constituents in the Central Point subarea are shown in table 18. These and all other available data show the following:

1. DO concentrations were below the State standard in 54 of 273 measure ments in this subarea; 43 of the low concentrations were noted during diel studies. Most of the other low concentrations were just below the State standard and often occurred early in the morning. Also, values were generally lower during the irrigation regimen than during the nonirrigation regimen.

2. State standards for pH were exceeded in 34 of 267 measurements, always in the daytime and mostly in the afternoon. Sixteen of the values exceeding 8.5 were noted during diel studies. Bear Creek at Upton Road had five such measurements. No trends were apparent.

3. Specific-conductance median values were lower during the irrigation regimen than during the nonirrigation regimen. This is a result of dilute irrigation water mixing with natural stream water. As in the previous subareas, specific-conductance values tended to be higher in the 1977 water year than in the 1976 water year.

4. Fecal coliform concentrations exceeded the State standard in 54 of 179 measurements. Concentrations were often higher during the irri gation regimen compared to the nonirrigation regimen. Also, higher concentrations and higher flows occurred during the 1976 water year than during the 1977 water year. All samples from Whetstone Creek during the 1976 water year met the State standard. Fifty-four is the highest number of measurements to exceed the State standard in any subarea, which can be explained by (1) the large number of measure ments in the Central Point subarea and (2) the large volume of irrigation-return flow in the Central Point subarea.

5. Fecal streptococci concentrations exceeded 1,000 colonies/100 mL in 66 of 119 measurements in the Central Point subarea. The trends and sources are similar to those discussed for fecal coliform.

6. Median turbidity values were higher during the irrigation regimen than during the nonirrigation regimen, which is probably the result of irrigation-return flow entering the streams. The median values generally are below the reference level of 15 Jtu during the nonirri gation regimen and above the reference level during the irrigation regimen.

7. Median suspended-sediment concentrations were higher during the irri gation regimen than during the nonirrigation regimen. This coincides with the increase in turbidity and also is probably the result of irrigation-return flow entering the streams. The median concentra tions were generally just below the reference level of 20 mg/L during the nonirrigation regimen and well above the reference level during the irrigation regimen.

76 Specific Total Dissolved Dissolved Kjeldahl Dissolved Iccal 1 ecal nitrogen phosphate No ot o\ >(!< " (imcromhos/ colilorm Suspended nitrate HydrologK samples Date 1)1 (percent P H lurbidity sediment as N as N as P SltC collected collection 25" C) Colonies; 100 ml (Jtu)

Talent lateral at Knowles Rd Irrigation 5 1976 115 0 8.0 0/4 178 290 1 2,000 2/3 16 28 0.04 0 03 McKen/ie jnd \\ittcnbcri; (19771 Phoenix Canal upstream of 2 1976 88 1 78 0 168 2,800 3/5 310 1/3 6 10 .7 38 Do Griffin Creek Irrigation 5 1976 95 0 7.8 0/4 236 1,100 I/I 980 0 18 51 .67 .20 Phoenix Canal downstream of Griffin Creek Irrigation 5 1976 98 0 7 7 0/4 222 920 2 1,200 2/3 16 40 .61 .18 Do Phoenix Canal at Jackson Creek Irrigation 5 1976 104 0 8.0 1/4 208 700 1 1,000 1/3 16 39 .54 -- .15 Da Phoenix Canal at Old Military Rd 5 1976 103 0 7.9 2 215 840 I 1,500 2/3 21 34 .35 .14 Do Irrigation 5 1976 88 3 7.6 1/4 220 610 1 1,200 2/3 13 40 .44 13 Do Gnffin Creek al Sterling Road 1977 90 1 8.0 0 460 60 0 220 0 1 40 .01 0.56 .05 Wittenberi: jnd McKen/ie (1978) Irrigation 1 1977 100 0 8.4 0 440 1,200 1 370 0 5 13 Griffin Creek at West Gritl'm Nommgation 2 1977 94 0 8.0 0 380 ISO 0 470 0/1 1 4 .00 .52 .05 D., Rd. Irrigation 4 1977 96 I 7.6 0 139 320 0 1,300 3 18 24 Griffin Creek upstream ol Nonirrtgatlon 2 1977 107 0 8.2 0 335 170 0 390 0 1 6 .00 .68 03 Do South Stage Road Irrigation 4 1977 100 0 8.0 0 182 450 0 1,200 2 15 49 Griffin Creek at Bellmger Nommgation 4 1976-77 98 0 7.7 1 196 60 0/3 920 1/3 6 20 .16 .14 .08 Do Lane Irrigation 5 1977 98 0 8.0 0 225 900 1 2,800 4/4 15 23 .54 .75 .02 Griffin Creek at Highway Nommgation I 1977 1,200 I 3,100 1 Do 238 Irrigation 4 1977 270 750 2 2,000 3 5 Gnffin Creek at Ross Lane Nommgation 2 1977 420 350 0 870 0/1 3 Do Irrigation 4 1977 292 690 0 3,100 3 10 Griffin Creek at BeaU Lane 5 1976-77 96 1 7.5 0 499 690 t 3,000 2/3 15 10 3.3 78 .45 Do Irrigation 5 1977 94 1 77 0 320 1.700 3 2,300 4/4 10 24 1.4 .96 .20 Griffin Creek at Scenic Ave. Nommgation 5 1976-77 104 0 7.9 0 420 55 0 2.200 3/4 5 10 2.5 .68 .47 Do Irrigation 5 1977 96 0 7.9 0 350 730 1 2,200 4 7 15 1.5 .84 .21 Do 6 1975-76 104 0 7.6 0/5 380 150 2 360 1 16 1.8 .6 .24 La Riviere (No dau-1 Irrigation 6 1976 96 1 8.0 0 262 1,200 4 2,000 5 24 1.0 .7 .22 Jackson Creek at Highway Nommgation 1976-77 100 0 8.0 0 215 270 0 410 0/1 10 14 .01 .24 .08 Wltlenbcrii and MiAciuie (1978] 238 Irrigation 2 1977 100 0 8.4 1 178 300 0 1,000 0/1 30 55 .25 .58 .09

Jackson Creek at BeaU Lane Nommgation 3 1976-77 99 0 7.7 0 309 200 0/2 1,500 I/I 7 8 2.0 .55 .12 Do 2 1977 93 0 8.0 0 264 2,600 1 2,100 2 25 67 .58 .9 .32 Jackson Creek at Scenic Ave Nommgation 3 1976-77 90 1 7.8 1 355 1,100 2 2.100 2/2 7 4 2.2 .88 .13 Uo 2 1977 97 0 7.9 0 240 2,200 1 4.500 I/I 40 124 .76 .90 Do 6 1975-76 104 0 7.6 0/5 352 2,800 5 1,400 4 17 2.2 .8 .14 I j Rivitrt inn d.itc) Irrigation 6 1976 97 0 7.9 0 239 1,500 5 2.600 5 23 .97 .5 .22 Bear Creek at Upton Road 1 1972 117 0 8.5 0 250 600 0 SIORI r Irrigation 6 1969-74 130 0 9.0 6 188 550 |/4 30 .12 Bear Creek at Vilas Road Nommgation 34 1975-76 Ashland Water Bridge Irrigation 30 1976 10 -- Dept.. Do Nomrrigai.on 20 1977-78 6 Do Irrigation 23 1977 II -- -- Bear Creek at Kirtland Rd. Nommgation 34 1975-76 Ashland Water Irrigation 30 1976 Dept., Do. 20 1977-78 Do Irrigation 23 1977 11 Do Nomrrigation 14 1972 8.2 0/2 270 16 44 .86 .42 .20 U S. Bureau ol Reclamation files. Irrigation 16 1972 7.6 0/4 262 16 38 .68 .68 .20 Do. Nomrrigation 6 1972-73 105 0 8.1 1 299 380 0/5 18 .4 .15 STORIT Irrigation 140 1/8 8.0 1/3 .19 '59 1971-73 269 230 0/1 36 Do. 1974-75 96 0/2 312 620 1/3 10 .14 Do. 1 974-75 100 0 £ °1 6 244 4,700 4 45 .13 Do 8 1976-77 108 0/7 8.0 0 286 130 0/7 6 12 .9 1.6 .21 Do Irrigation 6 1976 112 0 8.3 1 226 910 3 29 .6 .17 Bear Creek at Kirtland Rd. 4 1975-76 107 0 7.6 0/3 279 920 3 300 1 18 1.1 1.0 .22 La Riviere (no date) Irrigation 5 1976 98 0 8.0 0 225 790 2 2.300 3 28 .76 .7 .29 Do Nonimgatlon 4 1976-77 112 0/3 7.9 0/3 330 ISO 0 1,400 1/2 7 15 .87 .81 .26 Wittenberg and McKenzie (1978) Irrigation 1 1977 92 0 7.8 0 250 720 0 1,300 1 30 58 .55 .68 .13 Diel 9 am - 4 pm data Irrigation 8 1976 118 0 8.0 2 256 10 25 35 .6 38 McKenzie and Witienberg (1977). Diel, all data 23 1976 98 8/23 7.8 2/22 267 Do Bear Creek >/» mile downstream Nonimgatlon 32 1975-76 " Ashland Waier of Kutland Rd. 30 1976 -- Dept. Do. Nommgation 20 1977-78 Do Irrigation 23 1977 12 Diel 9 am - 4 pm data Nomrrigation 8 1977 122 1 8.2 1 407 200 0/1 440 0/1 1.3 .6 .24 Wittenberg and McKenrie (1978) Irrigation 17 1977 97 6 8.0 1 314 150 0/2 MO 0/2 18 .32 1.2 .30 Diel all data Nomrrigation 1 1977 95 4/25 8.0 8/25 423 Do. Irrigation 2 1977 74 31/49 7.9 6/49 350 Whetstone Creek at Kirtland 2 1976 130 0 8.2 1 278 180 0 44 0 4 4 .02 .06 McKen?ie and Wittenberg (1977). Rd. Irrigation 5 1976 110 0 8.3 1/4 177 160 0 260 1/3 6 9 .02 _. .06

77 8. Median nitrate concentrations of 1 to 3 mg/L as N in Griffin and Jackson Creeks during the nonirrigation regimen are less than the 5 to 8 mg/L as N from the Sulphur Creek drainage (P. R. Boucher and M. 0. Fretwell, U.S. Geological Survey, written commun., 1978). The average concentration of nitrate in water from 20 wells in this subarea is 8.0 mg/L as N; the average for six wells in the Griffin Creek and Jackson Creek drainages is 17 mg/L as N, and the average for four wells in the Whetstone drainage is 3.0 mg/L as N. These values suggest ground-water seepage could be a significant source of nitrate to streams, especially in the Griffin Creek and Jackson Creek drain ages. All concentrations are lower during the irrigation regimen than during the nonirrigation regimen. These lower concentrations result from dilution of base flow (ground-water seepage) by irri gation water and also from nitrate uptake by plants and conversion of inorganic nitrogen into organic nitrogen. The median nitrate concen trations are generally below the reference level of 1.0 mg/L as N except for Griffin Creek and Jackson Creek sites at and below Beall Lane and also Bear Creek at Kirtland Road during the nonirrigation regimen.

9. Median total Kjeldahl nitrogen concentrations generally were higher during the irrigation regimen than during the nonirrigation regimen. This agrees with the lower nitrate concentrations during the irri gation regimen and with results found by P. R. Boucher and M. 0. Fretwell (U.S. Geological Survey, written commun., 1978).

10. Median orthophosphate concentrations do not show any particular trend. Median concentrations are about one to six times the 0.06 mg/L as P reference level, and also three to 20 times the concentration con sidered necessary to support algal growths in lakes (Sawyer and McCarty, 1967).

Whetstone Creek receives irrigation-return flow and empties directly into the Rogue River upstream from the confluence of Bear Creek with the Rogue River. Upstream from the Whetstone sampling site at Kirtland Road, the creek spreads out to form a wetland area. Very slow flow and abundant vegetative growth cause the water to run through and around a "living filter." The resultant water quality in Whetstone Creek is similar to that above Emigrant Reservoir, in MID Canal at Bradshaw Drop, or in the Rogue River. In a similar situation in Wisconsin, irrigation-return flow and sewage-treatment-plant effluent pass through a swamp that acts as a polisher of the water. The swamp removed some suspended solids, turbidity, nitrogen, phosphorus, coliforms, and biochemical oxygen demand (Fetter and others, 1978). However, this practice requires land and consumes water through transpiration of the vegetation while improving water quality. A careful analysis would be needed to determine how efficient the method is for improving water quality.

Problems can also be identified with wetland areas. One concern is the potential for water-related disease in cattle that graze such wetland areas. One such water-related disease, bacillary hemoglobinuria, is caused by a bacteria species found in western areas of North America. These bacteria, during a soil phase outside of host animals, prefer (1) cattail marshes,

78 (2) hummock grasses, and (3) a soil-water environment where prolonged sat uration of an alkaline anaerobic condition exists (National Technical Advisory Committee, 1968). Several other diseases of livestock are associated with water in an anaerobic condition. Water management that prevents oxygen depletion serves to control the anaerobic condition.

Diel Sites

Each subarea previously discussed had at least one diel site. Site des ignations and year or years of data are listed, in downstream order, in table 19. (See pi. 1 for site location.)

Table 19.--List of diel sites

[Site locations shown on plate 1]

Bear Creek Year of Site drainage data number subarea Site name collection

107 Emigrant Bear Creek at Interstate 5 south 1977 of Ashland

101 Ashland Bear Creek at Mountain Avenue 1976 near Ashland

102 do. Bear Creek at South Valley View 1976 and Road near Talent 1977

108 Talent Bear Creek at Talent 1977

103 Phoenix Bear Creek at Suncrest Road at 1976 Talent

104 do. Bear Creek at Barnett Road at 1976 and Medford 1977

105 Medford Bear Creek at Table Rock Road 1976 and near Medford 1977

106 Central Point Bear Creek at Kirtland Road 1976 near Central Point

109 do. Bear Creek below Kirtland Road 1977 near Central Point

79 \

A Martek Mark II and Mark V were used to collect DO, pH, temperature, and specific conductance data; a pyrometer was used to collect solar-radiation data. These data were collected on a continuous basis for nearly 24 hours at most sites in 1977 and are reported as hourly values (Wittenberg and McKenzie, 1978, table 9). The 1976 data (McKenzie and Wittenberg, 1977, table 4) were collected at 2-hour intervals during daylight hours and twice during the night. Table 10 of the 1978 report and table 4 of the 1977 report list chemi cal and biological data for each of the diel sites.

The diel data were collected four times during the study, three times during the irrigation regimen (August 1976 and June and August 1977), and once during the nonirrigation regimen (October 1977). An example of data col lected is shown in figure 19. This figure shows that the diel fluctuations of solar radiation and dissolved oxygen have a similar relationship to time. However, water temperature, specific conductance, and pH seem to lag solar radiation by 2 to 4 hours in the daytime. Nighttime response to loss of solar radiation varied from a 1-hour lag for DO to an 11-hour lag for temperature. Both pH and specific conductance lagged by about 9 hours. Specific conduct ance decreases during a period of high solar radiation. This decrease may be caused by plant and aquatic vegetation uptake of calcium, magnesium, nitrogen, phosphorus, and other ionized constituents (Kennedy and Malcolm, 1977). The uptake of carbon by the biological system may affect the bicarbonate concen tration, in turn affecting specific-conductance values.

Dissolved Oxygen

Table 20 shows a summary of data collected during 1976 and 1977 at the diel sites, listed in downstream order. Analysis of these and other data shows the following:

1. Measurements at sites 107, 101, and 106 all met the DO State standard, except for October 17, 1977, when there was a very low discharge of 1.8 ffVs (see fig. 20) and 46 percent of the DO measurements were below the State standard. The general lack of low DO concentrations at these sites may be due to ammonia and nitrite concentrations as N being less than 0.15 and 0.02 mg/L, respectively, which probably means that nitrification was not significant.

2. At sites 102 and 108, the median DO concentration is 88 percent of saturation, and 47 percent of the measurements were below State standards. Some of the reasons for this are:

a. Mean ammonia and nitrite concentrations of 1.8 and 0.11 mg/L as N, respectively, indicate that nitrification is occurring and exerting an oxygen demand.

b. The stream bottom is mostly sand, which is not conducive to periphyton growth, as is reflected in the relatively low numbers of periphyton growing in this reach of the stream. Sites 102 and 108 had an average of about 300,000 cells per square inch compared to 9,000,000 cells per square inch in the rest of Bear Creek (see fig. 20). 80 SPECIFIC CONDUCTANCE, SOLAR RADIATION, IN MICROMHOS AT DISSOLVED OXYGEN, IN WATER TEMPERATURE, IN CALORIES PER SQUARE (5- *B DEGREES CELSIUS PH UNITS PtRCEN T SATURATION IN DEGREES CELSIUS CENTIMETER PER MINUTE > s - 5 j U « -* -.NJNJNjMNJtO PPPr'r' CQ.'0 _.< 5 o o o o bi b ui b 010 c! O O O CD 00 O N)^ 0) OOOOCOO) <0 N)O1 c o>' -» o 1 ! ' I J 1 1 i i i l i ii , .P ^ft 4^ 0 A * - I"l ^ Sis * * 0 . O W _4 0 \ - - ^*iCD C O1 ^T Q) O *. ^ ^ w tO -i £ w A A __ *»J C Q .3 p a 0 S 2 oo 9 ^2 d§ .* * 00 a o 2 m m - « 1 > -1 Q) t? Kl 2 CD M 2. -i I o .r w w _ 3 a o ° 0 ^ C C U) 1 .* s 5? z o ^ 0) x_ r+ g - ^ 1 > Q> 3 * (/) 3 * a * Q. *° en 1 * * 0 1 ' ' i . 1 ' 1 I.I 1 1 1 1 l. i l 1 I* 1 ~ " ' Table 20. Summary of diel data relating to dissolved oxygen

Dissolved oxygen Range Above Below Median 100 percent 90 percent Total Dissolved Percent percent saturation saturation ammonia nitrate BOD Periphyton of of (percent of as N as N ultimate Discharge (thousands of Site Date mg/L saturation saturation measurements) (mg/L) (ft3/s) cells/in^) 107 6/27-29/77 8.8-10.0 91-108 98 38 0 0.07 0.05 2.4 77 1,300 8/15-16/77 8.0- 9.2 93-106 99 48 0 .08 .05 3.4 56 320 10/17-19/77 7.8-11.2 80-112 90 29 46 .10 .16 3.8 1.8 3,600 101 8/23-24/76 7.9- 9.6 90-106 102 55 0 .12 .04 - - 33 - - 102 8/23-24/76 7.9- 9.6 90-102 96 18 0 2.0 .46 20 6/27-29/77 7.8- 9.3 87-104 92 18 8 1.7 .65 5.0 29 790 8/15-16/77 6.9- 9.2 84-105 88 16 53 1.9 .44 5.0 29 420 10/17-19/77 8.0-10.3 82-105 89 12 52 4.0 1.5 4.6 7.8 160 108 6/29-30/77 6.9- 9.5 80-107 87 33 54 .57 .33 4.3 31 200 8/16-17/77 6.4- 8.2 75- 97 85 0 75 1.4 .86 4.0 43 77 10/19-20/77 6.9- 8.9 70-93 72 0 88 .97 2.6 3.0 11 300

00 103 8/23-24/76 6.9-11.2 79-134 102 50 40 .20 .84 32 - - to 104 8/23-24/76 7.8-11.8 90-141 113 56 11 .15 .14 57 6/29-11.5 6.2-11.5 75-141 91 44 48 .14 .40 4.6 22 380 8/16-17/77 6.1-11.8 76-143 89 40 52 .16 .24 5.2 18 1,700 10/19-20/77 9.5-14.4 91-147 96 44 0 .12 1.9 3.0 23 2,300 105 8/23-24/76 7.8-11.7 91-140 103 55 0 .17 .11 59 2,300 6/30-1 /I 111 2.6-14.0 31-179 77 42 58 .22 .04 20 2.1 1,800 8/17-18/77 5.8-11.7 71-154 88 46 54 .19 .04 6.6 11 4,600 10/20-21/77 8.4-14.8 83-149 89 36 56 .05 .97 4.8 25 42,000 106 7/21-22/76 7.2- 9.9 80-124 96 50 42 - - 8/23-24/76 7.6-10.5 85-120 98 36 27 .15 .35 149 _ . 109 6/30-7 '/I /77 4.6- 8.3 54-103 72 8 64 .58 .17 9.0 14 680 8/17-18/77 5.8-10.3 67-128 82 40 60 1.0 .47 4.9 38 16,000 10/20-21/77 9.4-14.7 89-143 96 44 16 .12 1.3 3.8 41 32,000 3. Data from sites 103, 104, 105, 106, and 109 show a wide diel range of DO and a large number of measurements below State standards. These DO characteristics are caused by:

a. Mean BODU concentrations of 9 mg/L. Data collected during this study indicate that the main sources of BODu were probably sewage-treatment-plant effluent, drainage from a log pond, and combined sewers and storm sewers in Medford.

b. Mean ammonia and nitrite concentrations of 0.25 and 0.06 mg/L, respectively, indicate that nitrification is occurring. The com bination of nitrification, oxidation of carbonaceous organic material (BODU), and respiration of aquatic vegetation at a dis charge of 2.1 ft-73 caused the very low DO concentration of 2.6 mg/L at site 105 in June (see fig. 20).

c. Periphyton cell counts averaging more than 1 million per square inch, discharges of less than 30 ft^/s, and maximum temperatures often above 25°C all cause large amounts of oxygen to be produced during periods of high solar radiation. This explains the large diel range in DO at these sites.

Figure 20 indicates that DO is not sensitive to discharge at site 107 but is sensitive at site 105, with very high maximum and very low minimum values. This may be due in part to the high periphyton population and the low discharge occurring during the irrigation season, with high solar radiation and water temperatures. The general shape of the periphyton curves and the maximum DO curves tend to indicate that there may be a cause-effect relation ship because of oxygen being a waste product of algal metabolism.

Figure 21 shows a relationship between minimum DO and BODU , as described by equation 1.

DO = 11.6 - 6.91 logio BODU (1) where

DO = minimum DO, in milligrams per liter, and

BODu = ultimate carbonaceous biochemical oxygen demand, in milligrams per liter.

The regression equation has a correlation coefficient of 0.84.

The equation indicates that low DO concentrations are found where high BODu concentrations exist. It should not be concluded that the low DO con centrations are caused only by BODu, because nitrification is known to exist and periphyton are causing large diel variations in DO concentrations.