SECTION 4.0 MONITORING PLAN TASKS
The GBP monitoring plan is intended to provide the data necessary to evaluate the degree to which the commitments of the UA, EA, Supplemental EA, FONSI and consensus letter have been accomplished. To this end, flow, water quality, sediment, biota, toxicity and bioaccumulation monitoring have been identified as the tools for assessing the impacts of using a portion of the SLD to convey agricultural drainage water around the North and South Grasslands wetland areas.
The study area is located in the Grassland Subarea (SJVDP, 1990): the GBP study area is bounded on the east by the San Joaquin River from the Mendota Pool to Crows Landing; the Westlands Water District to the south; Interstate 5 to the west; and approximately the Stanislaus/Merced county line to the north. This area includes the Panoche Drainage District, the Broadview Water District, the Firebaugh Canal Water District, a portion of the Central California Irrigation District, the Pacheco Water District, the Charleston Drainage District, and the Grasslands Water District, as well as several state and federal wetland refuges.
4.1.2 Monitoring Station Locations and Data Uses
Fourteen monitoring stations have been established within the study area from which to assess changes in conditions from pre-project conditions (Table 4.1). These stations, labeled A through N, are located within the SLD (A and B), Mud Slough (C, D, E, and I), Salt Slough and the wetland channels (F, J, K, L, and M), and the San Joaquin River (G, H, and N). Figure 4.1 is a schematic showing the general routing of flow through the project area and the relative locations of the sampling stations.
Stations in the SLD are located at the drain inlet (A) and drain outlet (B). Data from these stations will be used to assess selenium loads, selenium transport (flux), water quality, sediment quality, tissue concentrations, toxicity and bioaccumulation. Selenium analysis will include both total selenium and dissolved selenium according to CVRWQB protocols. Also, at sites A and B, both total and dissolved selenium will be determined on a weekly basis to aid in addressing questions about selenium fate and the seasonality of selenium partitioning between dissolved and suspended.
Substations have been identified in the SLD to measure sediment volume and chemistry so as to make informed sediment management decisions. These substations have been identified by their locations: 1. between checks 17 and 18; 2. between checks 14 and 15; 3. between checks 10 and 11; and 4. between checks 1 and 2. Estimates of sediment concentration will be made to determine if and when sediments must be removed for disposal.
Stations in Mud Slough are located upstream of the discharge from the SLD (C), downstream of the discharge from the SLD (D), upstream of the confluence with the San Joaquin River (E), and in a seasonal backwater area (I). Data from some or all of these stations will be used to assess selenium loads, selenium transport (flux), water quality, sediment quality, tissue concentrations, toxicity, bioaccumulation, and aquatic community structure. Sampling in Mud Slough is intended to be comprehensive. In particular, it is intended to address the issue of "adverse environmental impact," as described in the UA.
Station F is the only station located in Salt Slough. Data from this station will be used to assess selenium loads, water quality, sediment quality, tissue concentrations, toxicity, bioaccumulation, and aquatic community structure. Since agricultural drainage from the GBP will be eliminated from Salt Slough as a result of the GBP, "upstream" and "downstream" sampling stations were not identified. Data from Salt Slough will be compared to historic data from the site in order to evaluate environmental improvement from removal of agricultural drainage water.
Stations in the wetland channels are located in Camp 13 Canal (J), Agatha Canal (K), San Luis Canal (L), and the Santa Fe Canal (M). Data from these stations will be used to assess selenium concentrations in order to assess and verify removal of agricultural drainage water and suitability of the channels for year round wetland water supply delivery. The connections from the Main Drain to the South Grasslands Agatha and Camp 13 canals are shown severed in Figure 4.1 indicating the rerouting of the combined agricultural drainage flow to the San Luis Drain.
Water quality and flow data from the drain outlet (B), Mud Slough (D), Salt Slough (F), and the San Joaquin River near Crows Landing (N) will be compared to historic flow and water quality data to evaluate and verify that there are no adverse impacts to San Joaquin River water quality due to the project.
Stations in the San Joaquin River are located upstream of the confluence with Mud Slough (G), downstream of the confluence with Mud Slough (H), and downstream of the confluence with the Merced River (N). Data from these stations will be used to assess selenium load, water quality, and tissue concentrations. Selenium loads and water quality have been identified as relevant indicators of change to the San Joaquin River system resulting from GBP. Tissue concentrations will provide confirmation of these parameters as indicators of system health. Sampling in the San Joaquin River is intended to serve as both compliance with CVRWQCB objectives for the river and trend monitoring.
The monitoring plan relies on the use of the following techniques: flow monitoring, water quality monitoring, sediment quality monitoring, biotic tissue sampling, community analysis, toxicity testing, and bioaccumulation analysis. Subsections 4.2 through 4.6 describe in detail the methods by which each of these monitoring techniques is applied.
Flow monitoring will achieve several objectives: 1. to determine compliance with flow limitations in the GBP; 2. to calculate, in combination with total selenium measurements, selenium loadings within the study area; 3. to calculate, in combination with boron and salinity measurements, boron and salt loading within the study area; and 4. to assess overall trends in the area's hydrology attributable to the GBP. Three separate flow monitoring devices/methods will be used, depending on the sampling location, the level of accuracy required, and the physical attributes of each site. These include an acoustic Doppler sensor in combination with a pressure transducer, a sharp-crested weir, and a simple stage reading using a rating curve.
Water quality monitoring will achieve the following objectives: 1. to calculate, at locations where flow measurements are also taken, selenium loadings within the study area; 2. to calculate, in combination with flow measurements, salt and boron loadings within the study area; 3. to assess spatial and temporal trends in water quality parameters of concern; 4. to characterize the habitats in which biotic samples are collected; and 5. to assess the selenium flux within water, sediment and biota. Either automatic composite samples, grab samples, or depth - width integrated samples will be used depending on the sampling location, the level of accuracy required, and the physical attributes of the site.
Sediment monitoring will accomplish several purposes. For compliance, it will be used to determine the quality and quantity of sediment residing in the SLD so as to make appropriate sediment management decisions. The four substations in the SLD will be sampled to determine whether sediment selenium concentrations are approaching a level requiring action (i.e., removal of sediment for disposal). Sediment monitoring will achieve other objectives: 1. to assess spatial and temporal trends in sediment quality parameters of concern; 2. to characterize the habitats in which biotic samples are collected; and 3. to assess of selenium flux within water, sediment, and biota.
Tissue sampling will achieve several objectives: 1. to assess spatial and temporal trends in selenium and boron biotic uptake; 2. to assess selenium flux within water, sediment, and biota; and 3. to assess "adverse environmental impact." Tissue samples will be collected from fish, invertebrates and plants. Avian eggs will also be collected should invertebrate selenium concentrations indicate substantial bioaccumulation. Fish sampling will be conducted using either seine nets or electrofishers, depending on the station location and the conditions at each site. Fish will be inspected for gross tumors and separated into game and non-game categories. Invertebrate sampling will be conducted using a dip net or kick net for aquatic insects and for crayfish. Plant material will be collected by hand. A simple community structure analysis will be conducted using the samples collected by these means.
Toxicity testing will achieve the following objectives: 1. to assess spatial and temporal trends in toxicity; and 2. to assess adverse environmental impact. Laboratory short-term chronic toxicity screening tests will be conducted using three species (alga, invertebrate, and fish) to evaluate both lethal and non-lethal endpoints. If significant toxicity is observed, definitive tests (dilution series) will be run quarterly. In addition, in-situ chronic toxicity tests will be conducted quarterly using caged fathead minnows.
As a part of the algal toxicity test, selenium concentration in control and test algae will be analyzed by USFWS to indicate occurrence of selenium bioaccumulation.
The frequency of monitoring proposed in this plan varies depending upon 1. objective, 2. station location and 3. technique. The sampling schedules will be evaluated as the program proceeds to verify that seasonal or event driven changes are being captured, and adjustments to the schedule made as appropriate.
Flow monitoring will be conducted on a continuous basis at stations B (drain terminus), D (downstream of SLD in Mud Slough), F (Salt Slough) and N (Crows Landing in the San Joaquin River). These stations have been identified as critical to assessing changes in water quality, including selenium loading, throughout the system and thus require the most accurate flow measurements. Flow will be measured daily at station A (drain inlet), biweekly at station J (Camp 13 canal), weekly at station M (Santa Fe Canal) and bimonthly at station E (second downstream station in Mud Slough).
Water quality data should reflect changes in environmental conditions which may result from this project. Water quality will be monitored on a weekly basis, with the exception of stations B (drain terminus) and N (Crows Landing). These are specific compliance points which will be monitored for selenium and EC on a daily basis. Stations D and F will also be monitored for EC on a daily basis.
Laboratory toxicity testing and analysis of control and test algae for selenium concentrations will be conducted on a monthly basis. In-situ toxicity testing will be conducted quarterly.
As sediment accretion is predicted to occur slowly through the GBP, monitoring will be conducted on an annual basis at the four substations in the SLD. At the primary stations, sediment will be monitored on a quarterly basis, and will be coordinated with biological monitoring.
Monitoring frequencies have been determined by the role each station and parameter plays in assessing compliance, providing screening information, and assessing environmental conditions.
Data will be reported in several formats, depending on the needs of the data users. Screening-level data (i.e., water quality and toxicity data) will be reported on a monthly basis to provide GBP participants with a timely picture of site conditions. Compliance data and data measuring environmental impact will be reported on a quarterly basis with biological data incorporated in every other quarterly report. The quarterly reports will provide GBP participants with a comprehensive view of site conditions.
In addition, each agency may produce its own data report for public distribution and review. These reports will be the usual reports which each agency regularly produces as part of its own data reporting procedures.
Flow is an important parameter in the measurement of selenium, boron and salt loads in the Grassland Basin. Loads are calculated by multiplying the concentration of the contaminant of concern (expressed in ppb or ppm) by the flow (in cubic feet/second) and then multiplying by an appropriate constant to convert the mass flux into lbs or tons, depending on the constituent. In previous monitoring programs, flow has been the most inconsistently monitored parameter. Flows within the Basin can fluctuate quite widely and are especially susceptible to rainfall runoff events.
4.2.2 Sampling Locations and Data Uses
The site description of the flow monitoring stations are listed in Table 4.2.1. Figure 4.1 shows the relative locations of the primary sites, including flow monitoring sites in north GWD and along the San Joaquin River. Many of the Monitoring Plan flow monitoring stations have been established for more than a decade and provide data that can be compared to the present flow conditions. These established sites were originally chosen for a variety of purposes, including water delivery accounting by GWD, water quality assessment of returns into the San Joaquin River by the CVRWQCB, and Basin water resource inventory by the USGS.
Flow data in the GBP Monitoring Plan is necessary for accurate selenium load computation at Site B to compare to selenium load targets set for the project (Table 1.1). Flow data at sites A, B, D, F and N will be used for load and mass balance calculations, and to perform comparative analyses with historic selenium, boron and TDS discharges to the San Joaquin River. Flow data collected at site E on a bi-monthly basis will be utilized with data from site D collected during the same sampling event to investigate potential selenium losses in-transit within Mud Slough. In addition flow data will be used in determining 1. seasonal flow patterns within Salt and Mud Sloughs; and, 2. influence of discharge from the SLD on the hydrology of Mud Slough.
Site A, located at Check 17 on the SLD, is the upstream flow monitoring site on the Grassland Bypass section of the SLD. It is an existing, inactive station, with a Stevens recorder, stilling well and access bridge. The existing broad-crested weir is fouled and in poor condition. This control structure will be replaced by twin adjustable sharp-crested weirs. Ventilation tubes will be placed below the nape on the downstream side of the weir to minimize flow turbulence at the weir crest.
Site B was chosen for its proximity to the terminus of the SLD and the availability of single phase power for the site. The USFWS wanted to minimize traffic along the SLD service road adjacent to the newly established wetland to the north-east of Kesterson Reservoir, and suggested locating the site as close to Gun Club Road as practicable. The presence of cattails and sediment accumulation immediately downstream from the Gun Club Road culvert had to be taken into consideration. A footbridge and a cantilevered bridge have been constructed at Site B to which the acoustic sensors, the stage and the water quality sensors have been attached. These sensors are connected to a data logger, which in turn is connected to a cellular phone and modem. This will allow the data to be telemetered to each of the participating agencies upon dial-up.
Sites D and F are USGS flow and water quality monitoring sites which have been in place more than 10 years. These sites were chosen because there are road bridges with bank stabilization at each location, facilitating the deployment of sensors and minimizing the potential for channel cross-section changes. Flow gauging is performed directly from the bridge at Mud Slough (Site D) and from a way cable at Salt Slough (Site F).
Site N, at the Crows Landing Bridge on the San Joaquin River, is a former flow gauging station that has been reactivated. The site is not ideal, as it is close to a bend in the river, and access to sensors from the bridge is a narrow walkway unsafe for personnel. The site retrofit, however, has added a gauge house on the north bank of the river, which has improved monitoring conditions, and a nitrogen bubbler sensor, which has significantly improved the accuracy and reliability of the stage measurement. An improved rating curve for the site will be developed over time.
Site E was initially chosen as a downstream Mud Slough biota sampling site, but it was subsequently decided to include downstream flow monitoring to allow for the computation of selenium load losses in Mud Slough between the SLD discharge point and the San Joaquin River. Flow monitoring will be performed bi-monthly to coincide with flow rating quality assurance monitoring at Site D. Since discharge is measured using the current meter technique at both sites during the bi-monthly site visit the data gathered at Site D can be used to check the stage-discharge rating at the same time. Selenium samples taken at both sites during the synoptic study will allow for the estimation of in-transit selenium losses.
Sites J and M (Camp 13 Canal and Santa Fe Canal, respectively) are not flow sites in the Monitoring Plan. However, daily flow data will continue to be collected and integrated when necessary. Flow monitoring will allow for computation of selenium and salt loads at each site, though neither of these load computations is critical to the monitoring program. Flow at these sites will continue to be measured daily by GWD staff using a stage over the weir boards to compute discharge.
The frequency at which flow is measured depends on the nature of the site, whether a control structure is present, the equipment available to measure and record flow measurements, and the budget allocated for flow measurement at each monitoring location. Where measurements are taken manually, daily or weekly measurements of flow using a staff gauge are most common. If a Stevens stage recorder is available at the site, it is possible to take hourly measurements. However, the chart from the Stevens recorder must be removed and read to determine stage. Most Stevens recorders are checked weekly or monthly, hence the data from these monitoring stations is unlikely to be useful for operations. Electronic sensors, such as pressure transducers which measure stage directly or indirectly, and shaft encoders, which convert analog Stevens stage recorder output to a digital signal, lend themselves to telemetry. With electronic sensors, readings are typically taken every 15 minutes or hourly. Frequent sampling is of little consequence if the flow monitoring site is not rated regularly and the relationship between stage and discharge is not checked at regular intervals. The frequency at which this re-calibration and site maintenance is required depends on the characteristics of the site and the flow conditions. Frequent calibration is performed for stream sites in unlined earthen channels susceptible to backwater effects and where sedimentation or stream bed erosion is likely.
4.2.4 Field Sampling Techniques
Control structures such as V-notch weirs and sharp-crested weirs are commonly used in irrigation canals to measure flow. The stage, measured a short distance upstream of the control structure, is functionally related to discharge, though each weir must be calibrated to account for conditions such as weed growth, obstructions and algal growth, that can affect this relationship. If measured with electronic pressure transducers or shaft encoders and relayed as digital signals to a data logger, the reading can be telemetered. In the case of the GBP sites, only site A is measured using a sharp crested weir. The discharge measured at Site A should have an accuracy of better than +/- 5%.
GWD gauges flow at canal check structures by measuring the height of the flow above the boards. This method of flow gauging has been sufficiently accurate for the District's accounting purposes. Flow is typically measured once per day using a graduated rule placed upon the top weir board of the control structure. Accuracy of flow measurement has not been determined at all sites, although monitoring by both GWD and LBNL along the Agatha Canal during 1994 and 1995 suggests that flows are within 15% of those measured with the acoustic Doppler and pressure transducer technologies. Although the GWD will continue to measure flow at Sites J and M, flow measurements at these sites are not critical for the GBP compliance monitoring program since compliance with the Use Agreement requires that selenium concentrations in wetland supply channels be lower than 2 ppb. Calculations of loads at these sites is not required for purposes of compliance monitoring, but suitable for mass balance calculations.
In large streams such as Mud and Salt Slough and the San Joaquin River, where control structures are not available, flow measurements are made by using direct stage measurements and a stream rating curve. The rating curve for a gauging station is a graphical depiction of the relation between stage and discharge. Each station's rating curve represents the individual characteristics of each site which, in the case of a stream, may change from time to time after flood events, seasonally, or as a result of sedimentation or stream bed erosion. These changes result in a correction or "shift" in the fixed relationship between stage and discharge. Occasionally, downstream conditions may control the discharge, creating a "backwater" condition at which time the rating curve is no longer valid. During these episodes, flow measurements must be made directly. It is necessary to visit this type of flow monitoring station regularly to develop an accurate rating curve and to check the current stream rating. This subject is discussed at length in the USGS Quality Assurance Program for the GBP, found in Appendix D of the Quality Assurance Project Plan (USBR, 1996). Both Mud and Salt Slough stations are rated "good" by the USGS and should produce flow measurements that are accurate to within +/- 10 % during those times of the year when the Sloughs are not in backwater (i.e. stage is influenced by a downstream control).
Site N at Crows Landing Bridge has only recently been rated and hence has insufficient recent flow record to be assessed for reliability. Until this data is available the station should be designated "poor" at the present time with an expected discharge measurement error of more than +/- 15%.
Another measurement system, deployed at Site B, on the SLD, is an acoustic Doppler sensor, which measures flow velocity directly within the canal. The flow sensors are mounted on adjacent bridge piers at 2/10 ths and 8/10 ths of the average flow depth in the SLD, aligned to face each other across the canal. The sensors make measurements every minute and report a mean velocity every 15 minutes. The velocity measurements are combined with stage measurements, also taken every 15 minutes, to produce a discharge measurement. This measurement system is very accurate and is anticipated to produce flow measurements with an accuracy of between 1% and 5%.
Table 4.2.1 summarizes the field measurement techniques at each of the primary sites at which flow monitoring will be performed.
Stage measurements can be converted to discharge values and current shifts in site flow rating curves can be used to correct estimated discharge using standard analytical techniques. These techniques can be found in any hydraulics textbook or the USGS Water Supply Paper 2175 (USGS, 1982).
Flow measurement quality assurance focuses on verification of the stage-discharge relationship at the monitoring site and checking and recalibration of the sensors deployed at each site. At each of the USGS and USBR sites (Sites A,B,D,E, F and N), quality assurance protocols will be carried out in accordance with the USGS QAPP for the GBP (Appendix D in the GBP QAPP). This Plan describes the tasks performed during routine site maintenance, including cleaning and recalibration of sensors, comparing flow gauging with conventional current meter measurements taken from bridges, and in stream by wading and by boat, and computation of shifts in the stage-discharge rating.
A QAPP for the GBD sites Camp 13 Canal (Site J) and the Santa Fe Canal (Site M) will be prepared by Summers Engineering. At both of these sites the height of water passing over the weir boards is related to canal discharge. The plan will call for current metered surveys of the canal discharge and development of a standard rating curve for each site. The plan will also establish a methodology for determining the expected flow error at each site.
The California Regional Water Quality Control Board, Central Valley Region (CVRWQCB) has been conducting water quality monitoring of the lower San Joaquin River and the wetland channels and principal sloughs within the Grassland Basin since 1985. The data gathered has been used in developing regulatory programs for the control of agricultural subsurface drainage discharges to surface waters. It is anticipated that this effort will continue in the future, primarily for the purpose of monitoring for compliance with the Water Quality Control Plan for the Sacramento and San Joaquin River Basins (Basin Plan).
The CVRWQCB will conduct the water quality monitoring portion of the GBP, as the CVRWQCB and the GBP have common objectives and overlapping sampling areas.
A number of commitments were made by the GBD with respect to water quality in connection with the use of a portion of the SLD referred to as the Grassland Bypass. These commitments were expressed in the consensus letter to the CVRWQCB, the UA, the FONSI and Supplemental EA. These commitments include meeting certain monthly and annual selenium loads, not degrading water quality in the San Joaquin River relative to the no-project condition (including the salinity standard at Vernalis), and metering drainage discharges so that they do not violate applicable state, federal, and local laws and regulations.
There are also a number of assumptions expressed in the aforementioned documents which require monitoring to determine their validity. The assumptions are that with the use of the GBP, concentrations of selenium will remain below 2 ug/L in 93 miles of wetland water supply channels (including Salt Slough); and that the increased frequency of exceeding selenium water quality objectives in Mud Slough (north) (5 ug/L) will be offset by a reduction of violations in Salt Slough.
Specifically, the objectives of water quality monitoring are to evaluate the impacts of the GBP on water quality in the San Joaquin River, Salt Slough and the wetland water supply channels. Additionally, it is the intent of the monitoring program to evaluate compliance with Basin Plan water quality objectives and selenium load limits established in the UA and in the CVRWQCB Basin Plan.
4.3.2 Sampling Locations and Data Uses
Water quality sampling locations are depicted in Figure 4.1 and are described in Table 4.3.1. Data will be collected at the SLD, Mud Slough (north), the San Joaquin River, Grasslands channels, and Salt Slough.
4.3.2.1 San Luis Drain (Grassland Bypass)
Two sampling locations in the SLD have been identified for monitoring. Site A will be used to monitor the inflow of drainage to the SLD. Drainage is presently dispersed through multiple wetland channels. Combining drainage flows into one channel, as a result of use of the GBP, will provide a better accounting of the quantity and quality of the drainage.
Site B will be used to assess compliance with selenium load limits established in the UA and to be developed by the CVRWQCB in the waste discharge permit. Water quality data will be evaluated along with flow to assess selenium loads.
Four water quality monitoring sites have been selected on Mud Slough (north). Water quality data gathered at Mud Slough (north) will provide information regarding the impacts of the GBP on the Slough. Data will also be used to assess compliance with the CVRWQCB interim water quality goals and water quality objectives.
Site C is located upstream of the SLD discharges and will be used as a background or reference water quality site. Site D is located downstream of SLD discharges and will be used to evaluate impacts of the GBP on water quality of Mud Slough and for CVRWQCB compliance assessment. The specific location of sample collection for this site will be adjusted as necessary after SLD discharges are initiated. A spatial assessment of Mud Slough (north) downstream of the discharge will be conducted by measuring electrical conductivity, which will identify where complete mixing of the discharge with slough waters occurs. Water quality sampling for site D will be located at the bridge over Mud Slough unless it is determined that mixing of SLD discharge and Mud Slough has not occurred at the bridge, in which case the monitoring station will be relocated further downstream.
Site I is located in a Mud Slough (north) backwater area. Data from Site I will be used in conjunction with other data to assess potential impacts of flooding from Mud Slough (north) on backwater areas within Kesterson National Wildlife Refuge. Monitoring at Site E will provide water quality data to be used in conjunction with other data to obtain a mass accounting of selenium in natural aquatic environments.
Three water quality monitoring sites have been selected on the San Joaquin River. Site G (San Joaquin River at Fremont Ford) is located downstream of Salt Slough and upstream of the Mud Slough (north) confluence. This site is presently impacted by agricultural subsurface drainage. With the use of the Grassland Bypass, drainage will be discharged to the San Joaquin River downstream of this site. Monitoring at this site will allow the assessment of the assumptions made regarding water quality benefits as a result of the use of the Grassland Bypass. Water quality data taken from this site will be used, with biota data, to study recovery of a site formerly impacted by drainage.
Site H (San Joaquin River at Hills Ferry) is located downstream of the Mud Slough (north) confluence but upstream of the Merced River confluence. This site will provide data by which to evaluate water quality impacts to the San Joaquin River and for compliance with water quality objectives.
Sites N (San Joaquin River at Crows Landing) is located downstream of the Merced River confluence. This site is a CVRWQCB compliance point.
4.3.2.4 Grasslands Channels and Salt Slough
Five monitoring sites have been selected in the Grasslands wetland channels. These sites include Site F (Salt Slough), Site J (Camp 13 ditch), Site K (Agatha Canal), Site L (San Luis Canal), and Site M (Santa Fe Canal). These sites are presently receiving agricultural sub-surface drainage, but will cease receiving drainage as a result of the GBP. Water quality monitoring of these sites will allow evaluation of the assumption that water quality will improve in these channels, and that the increased incidence of water quality objective violations in Mud Slough (north) will be offset by a corresponding reduction in accedences objectives in Salt Slough.
Frequency of water quality sample collection is summarized in Table 4.3.1. The frequency of sample collection is based on data uses and the historic variability of the measurement. Comparison of hourly data collected over 48 hours (Thomas and Cooper, 1989), daily data (Westcot et al., 1992, Karkoski and Tucker, 1993), and historic data collected since 1985 of the CVRWQCB, indicate that weekly sampling adequately characterizes seasonal and temporal variations. Sampling at frequencies greater than once per week relate to compliance evaluation needs. For example, since certain water quality objectives are based on a 4-day average, samples must be taken daily at selected compliance points. In addition, daily flow and salinity measurement at key stations will allow timely assessment and coordination with downstream users to ensure the project does not adversely effect salinity conditions in the River.
4.3.3.1 San Luis Drain (Grassland Bypass)
Weekly samples will be collected at Sites A and B for selected parameters. A sample will be collected on a daily basis for total selenium at Site B (outflow of the SLD) using a 24 bottle, integrating automatic sampler. Daily monitoring of selenium loads discharged is required for compliance evaluation. In addition, weekly depth-width integrated samples will be taken from the footbridges at Sites A and B for analysis of dissolved and suspended selenium concentrations in the drainage water.
The water quality reference site on Mud Slough (north) (Site C) and Site D will be monitored on a weekly basis for boron and total selenium (Table 4.3.1), in order to assess compliance with the CVRWQCB water quality goals for Mud Slough (north) and to assess the changes in water quality in Mud Slough (north) as a result of SLD discharges. Site D will also be monitored on a continuous basis for EC and temperature.
Site E will be monitored on a bimonthly, synoptic basis for total selenium and EC. Selenium mass accounting studies will be conducted bimonthly using the data collected at Sites D and E during these visits. A bimonthly sampling frequency will allow evaluation of selenium discharges for the various environmental and agricultural management cycles.
Site I is a potential backwater site important for biological monitoring. Water quality sampling may be conducted to provide data in support of the biological monitoring at this site. The frequency of sampling for this study will depend upon the frequency of the occurrence of backwater at Site I.
The San Joaquin River at Fremont Ford and at Hills Ferry will be sampled on a weekly basis. Weekly samples should adequately characterize temporal variations and provide an adequate assessment of the changes in water quality in the San Joaquin River as a result of continued discharge of drainage (Hills Ferry) and from the removal of drainage (Fremont Ford).
A daily composite sample will be collected at Crows Landing. This frequency is necessary for evaluation of compliance with water quality objectives. A weekly grab sample will also be collected for quality control purposes.
The Grasslands channels monitoring sites (Sites F and J through M) will be sampled at a weekly frequency. This frequency will be sufficient to characterize water quality conditions to assess changes in water quality at these sites as result of removal of drainage.
Several sampling techniques will be used to collect samples, including grab, time and depth integrated. The techniques used at each location are summarized on Table 4.3.1. Because of the remoteness of the region and the staffing limitations, an auto-sampler will be used to collect time-composite samples and samples that must be collected more than once per week.
Grab samples will be collected using a stainless steel sampling device. This device is a 6-foot pole with a cage at one end which holds the sampling bottle. Grab samples will be collected from the stream bank. This technique will be used for samples collected at a frequency equal to or less than once per week.
Depth integrated samples will be collected by accessing the center of the channel and collecting a depth integrated sample from mid-stream. Depth integrated sampling will be utilized at sites with parameters which may not be evenly mixed in the channel (e.g. sediments). This technique will be used for sites requiring total suspended solids (TSS) characterization.
Time composite samples will be collected using a Sigma auto-sampler. Either a 4-day composite (1 subsample per day) or a daily (2 subsamples per day) composite will be collected. Samples must be taken at a greater frequency than once per week because water quality objectives for selenium are based on a 4-day average for Mud Slough (north) and the San Joaquin River at Crows Landing.
4.4.1 San Luis Drain Sediment Quantity
The purpose of this task is to assess the transport of sediment and selenium within the SLD by conducting annual measurements of sediment quantity. Three estimates have been made of the sediment in the SLD. These surveys were performed by the USBR in January 1985, by Summers Engineering for the GWD District in March 1987 and by the SLD-MWA in August 1995. Each was performed using a slightly different method of determining sediment volume.
The sediment is not uniformly deposited along the length of the SLD. In general, sediment tends to build up near the check structures. To obtain an accurate determination of sediment deposition, it is necessary to take more frequent readings near these structures. Sediment thickness measurements will be taken at the locations that were used in Summers Engineering survey (March 1987). The distances from the structures and locations at which measurements were taken are documented, and the sites can reliably be resampled. Measurements were not taken equidistantly; upstream and downstream of the structures were sampled more intensively. A list of the locations to be measured in the checks is presented in Table 4.4.1.
4.4.1.3. Frequency of sampling
An annual sediment survey of four reaches will be performed by the SLD-MWA. This will allow for the detection of movement of sediment within the SLD.
4.4.1.4 Field sampling techniques
Cross-sections of the SLD from Check 19 to the terminus are shown in Figure 4.4.1. There will be water flowing in the SLD during the sediment surveys. In order to obtain accurate thickness measurement, it is proposed that, at any given location, a measurement be taken along the length of the slope of the lining from the top of the lining to the water surface, and then, that a probe be used to take the measurement from the water surface to the sediment in the center of the SLD. It is likely that the sediments are not of uniform width across the SLD. Representative sites will be measured at various locations to confirm whether a measurement of the sediment taken in the center is accurate. The thickness of sediment, therefore, will be measured and determined arithmetically. Figure 4.4.2 illustrates the variables to be used in the calculation.
a. Water Level Calculations
The level of the water will be determined by measuring along the lining above the water level (X). The actual water level (h) will be determined by subtracting X from the total length of lining (X1) and converting it into a vertical distance:
h = 0.55 (X1 - X)
b. Depth of Sediment
The depth of sediment (d) will be determined by subtracting the reading (y) obtained from the sediment probe to the water level (h):
d = h - y
c. Cross-Sectional Area of Sediment
The cross-sectional area of the sediment will be determined by assuming that the upper surface of the sediment is flat and that it occupies a trapezoidal area. The formula for finding the area of sediment is as follows:
Area = 1/2 * (8 + (8 + 2 * d * 1.5)) * d
d. Volume of Sediment
The volume of sediment in the SLD will be calculated by averaging the cross sectional area between readings and multiplying by the length. The formula for the sediment volume is as follows:
Volume = (Average Area) * Length * 0.037
where length is the distance between probe readings and 0.037 is the factor by which cubic feet are converted to cubic yards.
Distances along the SLD between structures will be measured using a cherry-picker retrofitted with an odometer that is accurate to ± 5 feet. This instrument will be calibrated daily while the surveying is being performed. The vertical measurements will be taken with a pocket tape measure along the SLD lining, and from the markings along the sediment probe to measure the depth of water above the sediment. These devices will be inspected daily.
The data will be used to tabulate the quantity of sediment in the various reaches of the SLD.
4.4.2 San Luis Drain Sediment Quality
The purpose of in-drain sediment chemistry monitoring is to detect whether selenium levels in San Luis Drain sediments are approaching the California Department of Health Services criterion for hazardous waste. The monitoring of the selenium in sediments, coupled with flow and water quality information from the inlet (A) and outlet (B) sites, will also help to assess whether there is an influx or outflux of selenium between the sediment and the water column. Sediment samples will be analyzed for selenium and Total Organic Carbon (TOC).
The Monitoring Plan provides for sediment chemistry samples on annual and quarterly sites in the SLD. The purpose of monitoring the annual sites is to provide an intensive sampling of the SLD to provide an indication of whether sediments are accumulating selenium towards hazardous waste criterion levels (minutes of Sediment Task Group meeting, February 22, 1996). The annual sites are located in four reaches of the SLD, with three sites (beginning, mid-point, and end defined by accessibility) chosen to characterize each of four selected reaches of the SLD between the inlet and the terminus. These four reaches are: a. between Checks 17 and 18; b. between Checks 14 and 15; c. between Checks 10 and 11; and, d. between Checks 1 and 2. These locations were selected because of the unique characteristic of the SLD or adjacent lands in the area that might have an impact on the sediments (Nigel Quinn, pers. comm.). The reach between checks 17 and 18 was chosen because it is close to agricultural land; 14 and 15 for adjacent wetlands; 10 and 11 had previous data collection points so that a comparison might be made to prior data; and the SLD between 1 and 2 has had a seasonal wet and dry cycle for the past several years.
In addition to the four annual sites, quarterly sampling of sediment chemistry will occur at two sites within the Drain. These sites are:
Site A - a location immediately upstream of the inflow, selected to characterize the SLD sediments prior to the introduction of drainage water;
Site B - chosen for its location near the terminus, available power, and other related monitoring activities.
Together, the annual (4 sites) and quarterly (two sites) sampling of sites within the Drain will provide cost-effective and representative information about sediment chemistry of the SLD.
4.4.2.3 Field Sampling Techniques
Samples at stations in the SLD will consist of three composite samples per sampling location using a precise volume detritus and bed sediment sampler developed by LBNL (Quinn and Clyde, 1996). One sample will be zero to three centimeters, another three to eight centimeters, and the third, greater than eight centimeters. At sampling sites in the sloughs, only the first two depth intervals are collected. During the first sampling episode, both discrete and composite samples will be taken for comparison purposes. The discrete samples will be taken from the left and right sides of the drain or slough. Composite samples will be taken from both right and left, as well as center point sample locations. Care will be taken when sampling to insure that the actual bottom of the drain is sampled rather than the side slope. Where the thickness of bed sediment in the SLD is greater than 30 cm, a push tube sampler with an expandable end plug will be used.
The samples will be analyzed for total selenium and TOC by USBR contract laboratory. Selenium will be analyzed by continuous-flow hydride generation atomic absorption spectrophotometry, and TOC by combustion and automated carbon analyzer. All previous sediment data were analyzed by these analytical methods.
The in-drain sediment data will provide indication of any trends with respect to accumulation or depletion of selenium in the sediments, as well as distribution within the sediments. Coupled with water quality data from the inlet and outlet (A and B) stations, the sediment data will also help to indicate fate of selenium within the Drain. In addition, a single core of the entire sediment profile will be analyzed to compare selenium sediment levels in the SLD with the hazardous waste criterion level of 100 ppm to provide indication of the need for management action should the levels be increasing.
4.4.3 Other Sediment Monitoring
Other locations will be sampled to determine whether changes in sediment chemistry are occurring as a result of the diverting of contaminated agricultural drain water through the SLD. Sediment samples will be analyzed for total selenium and TOC.
Sites C, D, E, and F are located in the Salt Slough/Mud Slough system. Site C is located in Mud Slough upstream of the inflow from the SLD, and was selected for this reason. Site D is downstream of the SLD inflow. Influence of drain inflows, presence of a USGS gauging station, and an existing data base of sediment and water chemistry, were rationales for choosing this site. Site E is located on Mud Slough at Highway 140. A previous sampling site near this location was abandoned due to flooding and subsequent inaccessibility. Site F is located in Salt Slough near Highway 165.
Sediment samples will be collected quarterly.
4.4.3.4 Field Sampling Techniques
The techniques and sampling design rationale are identical to those stated for in-drain sediment sampling, with one exception. During periods of relatively low flow, sediment samples will be collected by wading in the sloughs. Personnel will stand downstream of the sampling location, facing upstream, to avoid spreading disturbed sediment over samples as they are collected.
Analytical techniques are the same as previously described for in-drain sediments.
The sediment data will be used to detect any accumulation of selenium in the sediments. The data will also be used in conjunction with biota data from the corresponding sites to assess potential risk or contamination pathways.
The purposes for tissue sampling in biological specimens are: 1. to assess the potential for adverse biological impacts to fish and wildlife resources; and, 2. to assess public health risks. For the GBP monitoring plan, food chain (aquatic plants, invertebrates, and whole body fish) samples will be analyzed for contaminant residues to assess impacts to fish and wildlife resources, while gamefish fillet samples will be analyzed for contaminant residues to assess human health risks. Established ecological risk guidelines for selenium can be used to interpret selenium body burdens in assessing impacts to fish and wildlife resources.
Collecting food chain samples for analysis is important since post-project contaminant levels along the Mud Slough corridor may be expected to reach the established ecological risk guidelines toxicity thresholds for selenium in represented biota. Biota contaminant residues in food chain compartments can be used to evaluate ecosystem health. For example, since selenium is bioacccumulative, elevated concentrations at lower trophic levels can be an indicator of elevated concentrations at higher trophic levels. Effects of elevated selenium at higher trophic levels are well documented, such as teratogenic effects on avian embryos. Collecting edible portions (fillets) of gamefish to evaluate the potential for adverse public health risks is important, since recreational and subsistence fishing are known to occur in the GBP.
Biological monitoring stations are:
Site C: Located in Mud Slough, upstream of the discharge point from the SLD into Mud Slough. This site represents an area that received drain water before the GBP, to be reflective of drainage water removal post-project.
Site D: Located in Mud Slough downstream of the discharge point from the SLD. This site represents conditions existing immediately downstream of the discharge point.
Site E: Located in Mud Slough between the discharge point from the SLD and the San Joaquin River. This site represents the conditions existing within the system prior to discharge to the San Joaquin River.
Site F: Located in Salt Slough. This station represents conditions within the system reflective of drainage water removal.
Sites G and H: Located in the San Joaquin River upstream of the Mud Slough confluence, and downstream of the Mud Slough confluence respectively. These stations represent varying drainage water influences within River.
Site I: Located in an historically seasonally inundated backwater area on Mud Slough downstream of the SLD discharge. This site represents conditions in a low flow depositional habitat relatively close to the point of discharge into Mud Slough.
Fish and invertebrates will be collected from all sites (C-I) on a quarterly basis, according to expected natural and drain water flow regimes. Sampling will occur in March (high flow), June (early summer irrigation), August (late summer irrigation), and November (low flow). This schedule will also facilitate taking biota samples to reflect temporal changes in drain water constituents. Pre-discharge baseline samples will be collected in the quarter preceding initial drain water discharges to Mud Slough.
Because aquatic insects are a major source of food for certain avian species during the breeding season, insect samples will be collected in the spring. Baseline waterfowl egg samples will be collected in spring along the Mud Slough corridor and in the future when indicated. Also, aquatic vegetation will be sampled in late summer (August) to evaluate contaminant loading in plants known to be consumed by waterfowl.
4.5.1.4 Field sampling techniques
Procedures and protocol for biota sampling to determine contaminant body burdens in fish, invertebrates, and vegetation will be standardized to complement recent or current studies conducted by USFWS and CDFG.
Fish: Fish monitoring is essential for the program because of their importance in wildlife food chains and because they would indicate any potential health risk to humans. Mosquitofish (Gambusia affinis) will be selected for monitoring, as it represents the most prevalent fish inhabiting both the SLD and sloughs. Mosquitofish may not be sufficiently abundant for sampling at the San Joaquin River stations, in which case another small species such as fathead minnows (Pimephales promelas), red shiners (Cyprinella lutrensis), or inland silversides (Menidia beryllina) will be selected for sampling. All of these species are important as forage for piscivorous fish and birds inhabiting the areas adjacent to both Mud and Salt Sloughs. Changes in fish species could be made in the monitoring program if it is ascertained that other species are found more consistently at certain sites. Selection of fish species to be sent for trace element analysis will be dependent on numbers and species collected at each sampling location during each sampling quarter. Fish specimens will be collected at all biological monitoring sites by dipnetting, seining or electrofishing.
Fish samples analyzed will include three replicates of adult fish, composited by species, at each sampling site. Each replicate sample will include composited whole-body tissue samples from 5 specimens to obtain a representative sample of a minimum of 2 grams (preferably 5 grams or more) of tissue.
Gamefish: Gamefish species are expected to vary among project stations and time periods, but the most common species of larger fish will be selected for analysis (at each collection location and time). Species likely to be collected include channel catfish (Ictalurus punctatus), white catfish (Ameiurus catus), bluegill (Lepomis macrochirus), green sunfish (Lepomis cyanellus), Sacramento blackfish (Orthodon microlepidotus), and common carp (Cyprinus carpio). Selection of fish species to be sent for trace element analysis will be dependent on numbers and species collected at each sampling location during each sampling quarter. Gamefish will be collected at all biological monitoring sites where they are available (other than in the SLD) by dipnetting, seining or electrofishing. Gamefish samples analyzed will include three replicates, composited by species, at each sampling site. Each replicate sample will include composited fillets from five fish per replicate (unless it is not practical to collect that many per station where larger fish are scarce) to obtain a representative sample of at least 2 grams (preferably 5 grams or more) of tissue. Since boron is of less concern from a public health standpoint, analyses after the first year may be limited to selenium.
Invertebrates: Crayfish (Procambarus sp.), which represent an omnivorous epibenthic foraging species, will be collected at all biological monitoring stations where they are available (other than in the SLD) by dipnetting, seining or electrofishing. Crayfish samples analyzed will include three replicates, composited by species, at each location. Each replicate sample will include composited whole-body tissue samples from enough specimens to obtain a representative sample of a minimum of 2 grams (preferably 5 grams or more) of tissue.
Aquatic insects such as water boatman (Corixidae), dragonflies (Odonata), damselflies (Odonata), and back swimmers (Notonectidae), which represent important food items for breeding waterfowl, will be collected from all biological monitoring sites (A through I); insects will be collected opportunistically utilizing dip nets, kick nets, and seines. Aquatic insect sample analysis will include three replicates, composited by species, at each location. Each replicate sample will include composited whole-body tissue samples from 5 specimens to obtain a representative sample of a minimum of 2 grams (preferably 5 grams or more) of tissue. The collection of a sufficient number of target insects to provide adequate sample sizes for chemical analysis on three replicate samples will be attempted but may prove to be impractical depending on relative abundance of target species.
If sample sizes are not adequate for analysis of both selenium and boron, then selenium will receive higher priority for analysis.
Vegetation: Instream and/or stream side vegetation such as widgeon grass (Ruppia maritima), sego pondweed (Potamogeton pectinatus), smartweed (Polygonum sp.), swamp timothy (Heleochloa schoenoides), and bulrush (Scirpus sp.) will be collected once per year in the fall from all biological monitoring sites (A through I). The most appropriate vegetative species will be selected at each site on the basis of its potential for consumption by birds, its abundance, and its expected long term occurrence there. Since interpretation of monitoring data will depend more on temporal trends than spatial differences among sites, it is not necessary to monitor the same plant species at all locations. The same species should be sampled consistently at each individual site once a species has been selected for that site. Vegetation samples analyzed will include three replicates, composited by species, at each location.
Each replicate sample will include composited plant material samples from enough specimens to obtain a representative sample of a minimum of 2 grams (preferably 5 grams or more) of plant tissue.
Biological specimens collected will be analyzed for body burden concentrations of selenium and boron as priority analytes. If funding allows, additional analyses may be conducted for pesticides and other man-made organics, priority metals, and inorganics. All analysis for selenium residues in tissue will be by hydride generation atomic absorption spectrophotometry (HGAA). All analyses for boron residues in tissues will be by inductively coupled plasma emission spectroscopy (ICP). Because fish and waterfowl foraging on insects, other macro invertebrates, and fish would consume the entire organism, chemical analyses will be performed on whole-body composite food chain samples for fish and wildlife effects assessment. However, for public health risk assessment purposes, fillets from the more common gamefish species will be analyzed. Concentrations of selenium and boron will be reported on dry-weight basis in all samples, and they also will be reported on wet-weight basis in gamefish.
The tissue sampling is intended to provide data to compare to known critical contaminant levels to detect and predict environmental risk to the systems impacted.
It is designed to show both increases and decreases of the most relevant contaminants in the impacted areas of the Mud Slough corridor and San Joaquin River System. There exists a large scientific database from which screening level criteria or relative background contaminant levels for both biota and humans can be drawn. It is from this database that numbers produced by the tissue sampling will be compared. Evaluation of potential biological effects (adverse and beneficial) may indicate that sampling be intensified, that addition of collections be necessary, or that protocols be streamlined.
4.5.2 Fish Community Assessment
An assessment of fish communities existing within the GBP area will be employed to evaluate changes in fish species assemblages both spatially and temporally as a result of the GBP. The assessment will describe species abundance and diversity, as well as general condition of collected organisms. There are several advantages in using fish assemblages to assess biotic integrity of stream systems: fish are present in nearly every stream system except ephemeral systems or those with severely compromised water quality; fish communities include a range of species that represent a variety of trophic levels; fish integrate the effects of water degradation; fish are easily identifiable.
Aquatic Communities Assessment monitoring stations are as follows:
Site C: Located in Mud Slough upstream from the point of discharge from the SLD. This site represents an area that received drain water before the GBP, to be reflective of drainage water removal post-project.
Site D: Located in Mud Slough downstream of the discharge point from the SLD, this site represents conditions existing immediately downstream of the discharge point.
Site E: Located in Mud Slough between the discharge point from the SLD and the San Joaquin River, this site represents the conditions existing within the system before it is discharged to the San Joaquin River.
Site F: Located in Salt Slough, this station represents conditions within the system reflective of drainage water removal.
Site G and H: Located in the San Joaquin River upstream of Mud Slough, and downstream of Mud Slough respectively, these stations represent varying drainage water influences within River.
Site I: Located in an historically seasonally inundated backwater area on Mud Slough downstream of the SLD discharge, this site represents conditions in a low flow depositional habitat relatively close to the point of discharge into Mud Slough.
Sampling will be conducted a minimum of twice annually during the summer (June, August). Collecting fish community samples during the summer months is important, as a primary constraint of the Index of Biotic Integrity (IBI) developed for the Sacramento-San Joaquin Drainage (Moyle et al. 1986) is that it be applied to summer fish populations.
Decisions to sample outside of the summer index period to obtain supplemental assemblage information will depend on 1. any funding limitations, or 2. contaminant loading in biota from the Mud Slough corridor reaching established ecological risk toxicity thresholds for selenium.
4.5.2.4 Field sampling techniques
Fish collection techniques employed will depend on stream size and whether or not the stream is wadable. Stream sample reach length will be determined by stream size and subsequent reach length needed to obtain a representative fish assemblage. Fish will be collected using both standard electrofishing and seining techniques. Regardless of capture techniques utilized, all fish will be pooled together to sort afterwards by species and age class (juvenile or adult). Depending on species abundance, the proportion of external anomalies per species will be determined by examining fish individually, or by examining each individual in a subsample and extrapolating for the total number of that species.
Fish assemblage information will be qualified by using the 8 integrated metrics defined by the Index of Biotic Integrity (IBI) developed for the Sacramento-San Joaquin Drainage. The metrics developed for this region are based on two premises: 1. native fish species predominate in undisturbed habitats, and 2. salmonids are generally associated with high quality water and habitat (Moyle et al. 1986). The IBI is an effective bioassessment method because it is quantitative and provides criteria to determine whether a habitat is excellent or poor; there is no loss of information in calculating the index value, thus the metric values are available to pinpoint the ecological values that have been altered; professional judgment is incorporated in a systematic and ecologically sound manner, unlike other assessment methods such as diversity indices (Karr et al. 1986).
To ensure fish survey data is representative of the fish assemblage within the pre-project area, it will be necessary to examine historical databases. Data comparability will be maintained by using similar collection methods and sampling effort at sites having similar depth and flow regimes. Precision, accuracy, and completeness will be evaluated along with sampling methods and site size.
Fish communities assessment will be used to improve the resolution of whether or not impairment or enhancement of the aquatic community is occurring.
The objective of the laboratory toxicity testing program is to evaluate the potential toxicity of the SLD discharge and the receiving water after discharge, using standardized bioassay protocols conducted under controlled environmental conditions.
The purpose of the toxicity testing program is to evaluate potential toxicity of agriculture drain water as it is conveyed through the SLD to Mud Slough and removed from Salt Slough. The toxicity testing program includes a combination of laboratory methods using standard protocols and field methods. At the same time, water samples will be collected for selenium and sulfate analysis. In addition, at the end of the test, control and exposed algae will be analyzed for selenium bioaccumulation.
Grab samples will be collected at the following sites for use in laboratory bioassays:
Site B - SLD at new bridge
Site C - Mud Slough upstream of SLD discharge
Site D - Mud Slough downstream of SLD discharge
Site F - Salt Slough at Highway 165
Control - Delta-Mendota Canal
Rationale for the selection of these sites have been previously described.
Samples from all sites except Site B have been used in two pre-project toxicity test events (December 95, February 96). Station B will not be sampled for toxicity testing until after the GBP is initiated. The rationale for the selection of these sites has been described elsewhere. The Delta-Mendota Canal (DMC) site was selected as a control site because it is the nearest freshwater source to the project area. The DMC water is considered to be of good quality which can be used as a dilution water in the event that definitive bioassays are required.
Current plans require monthly sampling and toxicity testing at the selected sites. However, should data over several months show little variability, testing frequency will be reduced. The information required to make such a decision will be based on specific species response to the SLD water and comparison between sites. The initial monthly sampling schedule should allow for a determination of the toxicity of SLD and its potential toxicity to Mud and Salt Sloughs.
Field sampling techniques will follow the protocol described in "Short-Term Methods for Estimating the Chronic Toxicity for Effluents and Receiving Water to Fresh Water Organisms" 3rd Ed (EPA-600-4-91-022) for fatheads and algae. The Daphnia magna 7-D test protocol is found in EPA-600-D87-080. The protocol is included in the QAPP. Grab samples will be collected as they are easier to collect and may capture potential peaks in toxicity.
Water from each site will be collected in a one-gallon bucket. The sample will be transferred to a 2.5 gallon cubitainer, stored in a cooler and transported back to the laboratory. Before sampling, the bucket and sample containers will be rinsed with site water. Samples for chemical analysis will be transferred directly from the bucket to the appropriate sample container. Nitric acid will be added to the 500 mL container for selenium analysis; no preservative will be added to the sample container for sulfate analysis.
Water for the laboratory study will be collected 3 times during the 7-day testing period; on test days 0, 2, and 4. The first sample will be used for test initiation and for test solution renewal on day 2. The second sample will be used for test solution renewal on days 3 and 4. The third sample will be used for test solution renewal on days 5, 6, and 7.
Test species include the larval fathead minnow, Pimephales promelas (less than 24 hours old), the cladoceran, Daphnia magna (10-d old) and the alga Selenastrum capricornutum (4-7 d old). The test species were selected for their sensitivity to selenium, diazinon and chlorpyrifos and tolerance of usual water quality of the study area. Fathead minnows are sensitive to selenium; Daphnia magna is sensitive to pesticides; the algal study will include a bioaccumulation component.
Laboratory techniques selected for toxicity testing include USEPA methods using the short term chronic bioassay protocol. These methods are generally used to evaluate the toxicity of an effluent to receiving water. Specific methods for culturing and conducting toxicity tests using fathead minnows and Selenastrum may be found in (EPA 600/4-91-022). All tests have chronic end points, either growth or reproduction. In addition, fatheads and Daphnia are scored for survival (acute end point). All testing will be conducted at the screening level, comparing the control against 100 percent test water.
Culturing and testing protocols for Daphnia will follow those found in "Short Term Chronic Toxicity Test Using Daphnia magna' (EPA 600-D87-080). This test exposes ten-day-old females to the effluent for seven days. Three broods are expected during this period. Deviations from the method protocol for this Daphnia test will include the use of 35 mL low density polyethylene exposure cups with 30 mL of test solution instead of 100 mL glass beakers. Experience indicates that no over loading of animals will occur using the smaller test chambers.
Water quality and chemical analysis will be performed on each grab water sample collected. Analyses will include pH, conductivity, dissolved oxygen, alkalinity, hardness (as calcium carbonate) sulfate and selenium. Alkalinity, pH, conductivity, and dissolved oxygen will be measured in the field. Sulfate and selenium will be analyzed by USBR.
4.6.1.8 Bioaccumulation studies with algae
After each algal bioassay, test and control replicates will be composited. Samples will be transported to USFWS for analysis of selenium. A determination will be made as to whether selenium uptake is greater at any site as compared to the control. Data will also be compared to selenium concentrations in the water.
4.6.1.9 Summary of quality assurance measures
Laboratory QA/QC measures will consist of following a written SOP for each type of test, including general laboratory procedures. Reference toxicant tests will be run with each test.
Data will be evaluated using the TOXIS statistical package, which includes USEPA flow through chart. Statistics may include Fisher's exact test, Probit, Spearman-Karber, Dunnett's Procedure, Steel's Many-one Rank and the t-test. Depending on data input, TOXIS selects the most appropriate statistics.
4.6.2 In Situ Toxicity Testing
The purpose of the in situ toxicity testing program is to determine whether direct exposure of test organisms to SLD water at selected locations results in toxicity to a sensitive species. Details of the program may be changed based on test results.
4.6.2.3. Frequency of sampling
The sites selected for the in situ toxicity testing program are
Site D - Mud Slough downstream of SLD discharge
Site F - Salt Slough near Highway 165
Control - Windmill Site on Kesterson National Wildlife Refuge (fresh water supply)
Site B - SLD Water (will not be used until SLD is in operation)
4.6.2.3 Frequency of sampling
In situ testing will be conducted quarterly. In addition to one pre-project base line test, in situ testing will begin within a week of the SLD initiation. Quarterly in situ testing will provide data concerning GBP water that will complement monthly laboratory tests and other biological studies being conducted over the course of the project.
The test species is fathead minnow Pimephales promelas, four and fourteen days old.
Field procedures/protocols are currently under development and will be fully documented in the final version of the QAPP.
Chemical and physical parameters measured at each site will include temperature, pH, dissolved oxygen, hardness and conductivity. Location of test sites is correlated with ongoing analytical programs conducted by other agencies involved in the monitoring program.
The in situ toxicity testing program will follow a written SOP to be included inn the QAPP. There will be minimal handling of test animals to reduce stress.
Data from the in situ toxicity tests will be presented with laboratory toxicity test results and the water quality and chemical analysis for each site.
