SECTION 2.0 PREVIOUS STUDIES AND OTHER MONITORING PROGRAMS
2.1 Overview of Studies and Other Monitoring Programs
Monitoring programs have been conducted in the project area by a number of agencies and their contractors since 1985 in support of research activities and water delivery operations. These agencies and contractors include the CVRWQCB, USGS, USBR, GWD, Lawrence Berkeley National Laboratory (LBNL), CDFG and Summers Engineering. A task group, made up of representatives from these agencies, was formed to develop a monitoring plan for the GBP. The first step taken in the development of a monitoring program for the GBP was the creation of a matrix which described both past and on-going monitoring of flow and water quality in the Grassland Subarea. This matrix (Table 2.1) was expanded to include sediment sampling and was included in both the 1993 and 1995 monitoring plan documents (USBR, 1993; USBR, 1995). The matrix identified monitoring locations common to the various agencies, identified any overlap of monitoring activities, and located sites that may have been monitored in the past, but where there was no current data collection activity. It was agreed early in the process of developing the monitoring program for the Grassland Subarea that the program should "piggy-back" on existing monitoring programs and research activities to the greatest extent possible, since this would provide the longest data record at individual sites, and would reduce the overall cost of the program. To the extent that existing sites were not adequate or non-existent in certain monitoring locations, it was deemed necessary to establish new sites.
From among the many pre-existing or newly established sites, the sites were designated as either "primary sites" or "secondary sites." Primary sites are monitoring locations at which monitoring of one or several media takes place that are considered necessary to accomplish the goals and objectives of the monitoring program for the GBP. These sites are designated with a "P" in Table 2.1. Site B, at the discharge point of the SLD, is the site at which compliance monitoring for selenium loading takes place. Stations labeled "secondary sites" and designated with a "S" in Table 2.1 are stations that are not essential for accomplishing the objectives of the GBP and are not part of the GBP monitoring program. They are listed because they provide information that may be useful in data interpretation and for research purposes in the future. Many of the secondary sites have been monitored intermittently and some have been eliminated.
The matrix in Table 2.1 provides a summary of the primary and secondary water quality monitoring sites in the proposed project area, organized according to the agency responsible for data collection, along with the sample station identification labels used by each agency. Figure 2.1 provides locations of primary monitoring sites with relative locations to major structures and transportation system. Table 2.1 also lists both the frequency of collection and the period of record for the flow, temperature, pH, water quality and sediment data at the primary sites collected to date. Where data collection is ongoing at a particular site no end date is shown under the period of record column in Table 2.1. The last column of the matrix indicates intended use of the data collected at each site.
Table 2.2 provides a summary matrix of biological sampling programs in the proposed project area. The matrix indicates the agencies responsible for the monitoring programs and the site identification codes at each site. The matrix is divided into columns for recent, current and proposed sampling of plants, invertebrates and fish. The use of the data and the period of record is provided in the two adjacent columns on the right side of the matrix.
2.2 Review of Previous Studies and Monitoring Programs
2.2.1 Water Quality Monitoring
Routine water quality monitoring within the Grassland Subarea has been performed by the CVRWQCB since 1985 at Crows Landing on the San Joaquin River, in Mud and Salt Sloughs, at sites within the GWD, and at outflow points from the major agricultural water districts. The current monitoring program involves periodic sampling to measure temperature, pH, electrical conductivity (EC), selenium, and boron. Most sites are sampled weekly, others are sampled monthly and in the case of the Crows Landing, daily samples are collected using an autosampler (Table 2.1). Five CVRWQCB sampling stations (MER542, MER531, MER538, STC512, and STC504) correspond to the locations of the primary stations (D,F,G, H, and N), and water quality data from these sites is included in the compliance monitoring program plan. A data summary report and an interpretative report are published annually by the CVRWQCB for these monitoring stations.
Monitoring for the Grassland Water Task Force (GWTF) is collated in an annual report by Summers Engineering. The GWTF is comprised of agricultural water districts, State and Federal refuges and the GWD, all of which discharge to the San Joaquin River. The numerous monitoring stations included in this report are located on the San Joaquin River, along Mud and Salt Sloughs, along conveyances within the GWD, and at outflow points from the major agricultural water districts. These stations are usually sampled monthly for EC, selenium, and boron; some are also monitored for flow. The chemical analysis performed on these samples measures total concentrations of selenium and boron in the sample and does not discriminate between the dissolved and suspended phases of these constituents. Four GWTF stations correspond to the primary stations in the current monitoring program; two are active (GL-22a and GL-20), one has been eliminated (GL-21 E1 [in 1989]), and one is a station on Mud Slough that was relocated from Highway 140 (GL-19) upstream of the vicinity of proposed Station D. In addition, the GWTF previously monitored Mud Slough at Gun Club Road (GL-15E, eliminated in 1987), which is upstream from proposed Station C. Except for the Gun Club Road Station (GL-15E), all the GWTF stations correspond to CVRWQCB stations. One of the discontinued stations (GL-21E) has been reopened in the current monitoring program.
The San Joaquin River at Fremont Ford (Station G) is a site that has been monitored in the past by USBR for EC, selenium, and boron. USBR has also previously collected data at nine secondary stations (Table 2.1) that may be used to provide background information.
The Department of Water Resources (DWR) measures flow at a number of stations along the San Joaquin River, including Newman, which is located within the GBP area. The DWR also measures flow in Salt Slough at Lander Avenue. These DWR stations (B00470 and B07375) are at the same location as two proposed primary stations (F and G).
The Salt Slough and Mud Slough sites (Stations D and F) were monitored by the USGS until 1994. Responsibility for data collection at these sites was then assumed by the San Joaquin River Management Program (SJRMP) Water Quality Subcommittee. Maintenance was performed by the DWR and the USGS. In March 1996, the USGS resumed operation of these sites. Dataloggers, cellular telephones and sensors for stage, EC and temperature were installed at each site during September 1995. The USGS has also been charged with rehabilitating a previously abandoned gauging station at Crows Landing under a recently signed contract with USBR. This station is currently reporting stage, EC and temperature. Flow is being calculated using a recently established rating curve for the site. The SJRMP Water Quality Subcommittee is utilizing data from the Crows Landing, Mud and Salt Slough sites, as well as other sites, to produce water quality forecasts for EC in the San Joaquin River at Vernalis.
Other flow monitoring within the Grasslands is performed jointly by Summers Engineering and the GWD as part of the GWTF. Much of the flow monitoring performed at these sites is for water accounting purposes and for scheduling of water deliveries.
The most intensive study of flow, water quality and sediment selenium in recent years in a single conveyance within the GWD was conducted during 1994 and 1995 by LBNL on the Agatha Canal within the GWD (Quinn et al, 1995). Data were collected at two locations on the Agatha Canal in this study, the objective of which was to determine the mechanisms responsible for selenium in-transit losses within the Grasslands canal systems. The acoustic Doppler flow monitoring equipment used in this LBNL study has been moved to Site B on the SLD.
2.2.3 Biological and Toxicity Monitoring
Previous research studies have shown that dissolved concentrations of trace elements such as boron and selenium occur at elevated levels in tile drainage water (Presser and Barnes, 1984, 1985; Shelton and Miller, 1988). Selenium, in particular, may accumulate to potentially toxic concentrations in fish and aquatic birds, primarily through bioaccumulation associated with contaminated prey (Ohlendorf et al., 1986; Saiki and Lowe, 1987; Ohlendorf, 1989; Saiki, 1989). Baseline contaminant information on selenium, boron, and other chemical constituents is available for Mud Slough, Salt Slough, and the San Joaquin River from previous investigations (Saiki, 1985a, 1985b; 1986a, 1986b; Ohlendorf et al., 1987; White et al., 1987, 1988, 1989; Ardans et al., 1988; Saiki and May, 1988; Leland and Scudder, 1990; Saiki and Palawski, 1990; SWRCB, 1991; Saiki et al., 1992, 1993), as well as from ongoing investigations being conducted under the direction of the CVRWQCB as part of the routine water quality monitoring and biological body burden contaminant studies by USFWS and CDFG. Water, sediment, detritus, aquatic plants and invertebrates, and fish samples were analyzed for selenium and/or boron (Saiki, 1985a, 1985b, 1986b; Saiki and Lowe, 1987; Ohlendorf et al., 1987; Saiki and May, 1988; Hothem and Ohlendorf, 1989; Saiki and Palawski, 1990; Schuler et al., 1990; Saiki et al., 1992, 1993).
Biological monitoring programs have been carried out by the USFWS and CDFG since 1992 to ascertain environmental impacts of elevated selenium levels in water. The USFWS has five active biota sampling stations along or near Mud and Salt Sloughs. Each site was sampled monthly from March through September 1992. Types of samples taken include crayfish, non-gamefish, immature gamefish and water boatmen. These samples, together with water and sediment samples taken at the same sites, were analyzed for selenium and boron. The three USFWS sampling stations along Mud Slough and Salt Slough correspond to Stations C, D, and F . The USFWS monitoring had been conducted on Mud Slough at Gun Club Road, but this station was moved downstream to Station C at the outflow from S Lake. The other two USFWS stations on Salt Slough at Wolfsen Road Bridge and on Kesterson National Wildlife Refuge at East Big Lake provide data that might be compared to GBP. Five USFWS sites previously sampled for water, sediment and biota correspond to primary stations or are located nearby (Stations C, D, F, G, and H).
The CDFG conducted quarterly sampling by electrofishing and hoop-netting at five stations along the San Joaquin River and Mud and Salt Sloughs from April 1992 to Spring 1993 as part of the Selenium Monitoring and Evaluation Program (F. Wernette, CDFG, pers. comm.). The goal of the study was to measure selenium and other trace elements in biota from suspected problem areas and to determine whether these elements occurred at levels harmful to fish and wildlife. The fish species collected included channel catfish, white catfish, green sunfish, bluegill and crayfish. Two stations sampled by CDFG in the past in Mud and Salt Sloughs are sufficiently close to provide background data for proposed Stations D and F. In addition, CDFG has sampled fish from proposed Station E during 1991. The CDFG also has sampled fish and invertebrates from the San Joaquin River upstream of the Merced River confluence and downstream of the Newman Wasteway.
The USGS sampled freshwater clams (Corbicula flumina) at a number of sites within the project area during 1985 (Leland and Scudder, 1990). Several of the USGS sites (listed in Table 2.2) provide background toxicity information for comparative purposes.
The USBR has monitored sites in the vicinity of Mud Slough and the SLD as part of the Kesterson Reservoir Biological Monitoring Program. Samples have been collected each year since 1986 from various sites in the Reservoir and analyzed for selenium. These samples include bird eggs, small mammals, vegetation, invertebrates, and soil.
Sediment samples have been collected quarterly by USBR since August 1993 for selenium and boron analysis from two monitoring locations within the SLD (Check 2 and Check 10); from each of the primary stations in Mud Slough (Stations C, D, and E); from Salt Slough (Station F), and annually from the backwater site (Station I). Separate samples of the top and bottom sediments were taken at three locations across the channel. The samples taken on the channel transect were composited. After September 1994, separate sediment samples were taken at each of three depth ranges (0 - 30, 30 - 80 and > 80mm) with a precise core sampler designed for submerged sediments to help answer questions about selenium transport within the sediments and selenium bioavailability. Samples were composited for each of the three channel sampling points on the transacts as before.
In September 1994, and again in March 1996, a Sediment Task Group, comprised of GBP Monitoring Plan Team Members, conducted a sediment survey at the upper, middle and lower end of five channel reaches along SLD. The sampling protocol was the same for both surveys, although in the 1996 survey the deepest sample was taken from 80mm to make contact with the SLD lining in order to obtain a total sediment depth and minimize sampling error. In the September 1994 survey, the chosen channel reaches were considered to be representative of the range of conditions observed along the SLD. The reaches were between a. Checks 1 and 2; b. Checks 10 and 11;
c. Checks 15 and 16; and d. Checks 27 and 28. The second survey, completed in March 1996, eliminated the reach between Checks 27 and 28 and added sampling points a. Between Checks 17 and 18, b. upstream of Check 18, and c. at Site B, which is the compliance point on the Grassland Bypass.
Sediment surveys were conducted in the SLD in 1985, 1987, 1995 and, most recently, in 1996. These surveys, together with sediment depth measurements at these and three other stations within the SLD, as well as monitoring of Total Suspended Solids (TSS) in water at Stations A and B, allow for the estimation of selenium and boron movement within the sediments and provide information on sediment deposition and movement. This data will assist in the evaluation of the sediment as an exposure medium for aquatic organisms. Selenium concentrations were measured as total recoverable selenium consistent with previous chemical analysis performed on SLD sediments.
A laboratory experiment to determine mass transfer rates and potential mobilization of selenium from the SLD sediments to fresh water flowing in the drain was conducted by Oleh Weres (1993). Weres' experiment showed that selenium was immobilized within the sediment by geochemical processes, and that soluble species accounted for a small fraction of the selenium in the SLD. Weres hypothesized that a large fraction of boron would be extracted rapidly in the water added to the SLD, but very little selenium. The initial inventory of soluble selenium and boron would be flushed from the SLD in the first full volume discharged, equal to approximately 900 acre-ft, which would require 36 hours to drain at a flow rate of 300 cfs. Weres concluded that after the initial discharge of selenium and boron, the amount of these constituents transferred to the water from the sediments might not be detectable analytically.
The anticipated flow rate in the SLD will not exceed 150 cfs, which is about one half the design flow of the SLD. The Weres experiments used fresh water rather than agricultural drainage water and hence did not measure selenium flux from the water column into the sediments. Loss of selenium to the sediments would reduce the load in the drainage water but increase the inventory in the SLD sediments.
Selenium and boron concentrations in organic detritus were much higher than those in sediments from stations in or near the project area in an experiment conducted by Saiki et al., 1993. Research conducted by LBNL (Quinn et al., 1995) has shown that the organic detritus which appears to accumulate in the stagnant SLD does not build up in a flowing system such as the Agatha Canal. Quarterly sediment samples taken from the Agatha Canal showed no visible organic detrital layer. Sediment size analyses were predominantly silty-clay in composition. A similar sediment size analysis conducted by the USBR Laboratory in Denver on the SLD sediments was inconclusive. The high organic fraction prevented the laboratory from using standard methods. The Laboratory classified the SLD sediment samples as a "muck".
