Station locations

The original proposal included the following six stations: (Figure 1)

1) DWIN - downstream of Dwinnell dam at Riverside Drive;

2) A-12 - Hwy99-97 Grenada cutoff river crossing;

3) MGR - Montague-Grenada Road river crossing;

4) HWY3 - Highway 3 river crossing;

5) 263 - old Highway 99 river crossing; and

6) CANAL - the canal below Dwinnell Dam at Big Springs Road.

The current study added the following stations:

7) ELR - East Louie Road river crossing (upstream of Big Spring Creek;

8) HWY5 - Anderson Grade Road river crossing upstream of Yreka creek, downstream of Highway 5;

9) AGER - Ager Road river crossing (area of diversion impoundment).

The respective stream mileage measurements for each station are presented in Table I, as measured from aerial photos contained in the publication: Klamath and Shasta Rivers Environmental Atlas, (DWR 1980). Aerial photo approximate scale is: 1 inch = 500 feet.

Table I. Mileage of Shasta River sample stations from confluence with Klamath River.

263 (Highway 263 )	7.25
HWY5 (Anderson Grade)	8.00
AGER (Ager Road)	10.55
HWY3 (Highway 3)	12.80
MGR (Montague/Grenada Road)	15.20
A-12 (Highway 99/97 cutoff)	21.00
ELR (East Louie Road)	31.85
DWIN (Riverside Drive)	37.75

Data Collection Period

Data discussed in this report were collected by various Regional Board staff during the period from July, 1986 through June, 1992. From April, 1991, through June 29, 1992, intensive sampling was performed. Scheduling of sample events covered early morning, mid-day, through late evening in order to best measure the fluctuations of pH and dissolved oxygen levels from biological activity, as well as to get an idea of daily temperature fluctuation at each of the various stations. Sampling was performed throughout the irrigation season, and to a lesser degree during the fall and winter.

Field Measurements

Water quality field measurements included: dissolved oxygen, pH, temperature, and specific conductance. Dissolved oxygen was measured with a Yellow Springs Instrument Co. (YSI) model 57 meter, air calibrated at the beginning and end of each sampling run. The Winkler method for measurement of dissolved oxygen was used for some of the earlier measurements of river dissolved oxygen, and for some preliminary Light Bottle/Dark Bottle tests for algal productivity. Comparisons yielded satisfactory replicate values for the model 57 YSI meter and Winkler analysis. Thereafter, the model 57 was used for all measurements. The YSI model 57 has a manufacturer's accuracy and precision rating of +0.8 mg/L for dissolved oxygen. Conductance and temperature were measured with a YSI model 3000 T-L-C meter. The YSI model 3000 has a manufacturer's accuracy and precision rating of +8 micro-mhos for conductance and +1 C for temperature. The pH measurements were obtained with a Cole-Parmer Model 59411-00 meter, calibrated at the beginning and end of each sampling run, and checked periodically throughout the day, as temperatures varied. Cole Parmer model 59411-00 has a manufacturer's accuracy and precision rating of +0.2 pH.

Generally, a quality control sample was obtained at the beginning of each sampling run and retained for replicate analysis of conductance and pH at the end of the run. Replicate field measurements for QA/QC purposes are presented in Appendix 1. For thirty-six sets of field replicates during the period from April 1991 through June 1992, the manufacturer's specifications for accuracy were exceeded three times for conductivity, with the greatest difference being 14 micro-mhos(4.8% of the measured value of 293 micro-mhos). The manufacturer's specification for pH accuracy and precision were met in all replicate analysis. The greatest difference was 0.2 pH(2.6% of the measured value of 7.9 pH).

Analytical laboratories were subject to rigorous QA/QC procedures and performance evaluation protocol which are a standard component of our analytical services vendor contracts.

Laboratory Analysis

Water samples were analyzed at contract laboratories for macro-nutrients (total nitrate, total Kjeldahl nitrogen (TKN), total ammonia as N, total phosphorous), mineral series (alkalinity, bicarbonate, free carbon dioxide, total carbon dioxide, carbonate, chloride, conductivity, hydroxide, sulfate, filterable residue, pH, hardness, silica, calcium, iron, magnesium, sodium, boron, potassium), turbidity, and trace metals analysis for arsenic, aluminum, and copper. Table II is a matrix of stations and sample analyses showing the number of times each parameter was measured from June 1986 through July 1992.

The contract lab which performed the ammonia analysis from July of 1990 through June of 1991 reported down to a detection limit of 0.01 mg/L. However the laboratory which analyzed the samples from July of 1991 through June of 1992 reported only down to a minimum detection limit of 0.2 mg/L. This is significant, in that under some temperature and pH conditions, it would be impossible to determine compliance with the USEPA criteria for ammonia, since sample results were below detection. For example, for a sample with pH of 8.75 at a temperature of 25 C, the U.S. EPA national ambient water quality criteria for total ammonia to protect aquatic life (continuous concentration, 4-day average) is not to exceed 0.15 mg/L total ammonia as NH3. This is equal to an analytical result of 0.123 mg/L ammonia as nitrogen (NH3 x 0.822 = ammonia as N).

Table II. Matrix of stations and number of sampling events for each parameter. Shasta River for period from June 1986 through July 1992.