Bridge-Seton Water Use Plan. Monitoring Program Terms of Reference. BRGMON-12 Bridge-Seton Metals and Contaminant Monitoring Program

Transcription

1 Monitoring Program Terms of Reference BRGMON-12 Bridge-Seton Metals and Contaminant Monitoring Program March 29, 2012

2 Bridge-Seton Water Use Plan Monitoring Program No. BRGMON-12 Bridge-Seton Metals and Contaminant Monitoring Program 1 Monitoring Program Rationale 1.1 Background and Assumptions One of the issues identified in the Water Use Planning phase for the Bridge-Seton system was that the new N2-P2 operation regime may alter the hydrodynamics of the system. One consequence of this is the potential for metals and other contaminants to be mobilized from sediments, and re-introduced into the system, potentially leading to changes that could adversely affect the aquatic food web and/or human health. Monitoring of metals concentrations in water, sediment and biota prior to and following operational changes (see major findings below) will serve as the benchmark from which to determine whether or not changes have occurred. While monitoring of hydrodynamic changes and the physical potential for re-mobilization of metals or other contaminants was contemplated, ultimately, changes in metals concentrations within environmental media is considered the best endpoint. Major findings of historic monitoring of sediment and fish tissue monitoring in 2000 (Aqualibrium, 2001) and 2008 (including water quality in 2008; Azimuth, 2009), and water quality in (Azimuth in prep) were: Sediment Chemistry The ranges in concentrations of most sediment metals were similar between Carpenter Reservoir and Seton Lake and were strongly determined by grain size. Although several metals (arsenic, cadmium, chromium, copper, mercury and zinc) exceeded guideline concentrations for the protection of aquatic life in both Carpenter Reservoir and Seton Lake, the regional concentrations of all of these metals (except zinc) are of a similar magnitude and are typical of this mineralized region of BC. Metals were lower in Downton Reservoir, Tyaughton Creek and Bridge River because of coarser grain size. Inorganic mercury is elevated in Tyaughton Creek and offshore of Tyaughton in Carpenter Reservoir (i.e., due to historical mining activities in the Tyaughton Creek watershed). Temporal and spatial patterns in sediment metals between 2000 and 2008 were closely related to differences in sampling location and sediment grain size and did not differ substantially between years. Water Chemistry Water chemistry of Bridge River was identical to Carpenter Reservoir above Terzaghi Dam. Some metals (cadmium, chromium, copper, iron and zinc) exceeded at least the 30-day average BC Ambient Water Quality Guidelines (AWQG) in upper Carpenter Reservoir, Tyaughton Creek (only mercury) and Downton Reservoir. These are the same metals that exceeded local and regional sediment guidelines, again suggesting that these metals are regionally elevated due to natural mineralization. During , water quality from Carpenter Reservoir into Seton Lake was being monitored every 3 weeks to provide a medium-term record of water quality and metals loading into Seton Lake from upstream sources and be used to gauge relative contributions. Fish Tissue Chemistry Regarding fish, there are some natural differences in biology between the systems that may influence patterns seen in some BC Hydro Page 2

3 bioaccumulative metals, particularly mercury. For example, larger fish of many species will naturally have higher mercury concentrations. In Carpenter Reservoir, the average size of rainbow trout was larger, while bull trout and mountain whitefish were smaller than Seton Lake and Bridge River fish. Tissue mercury concentrations of 400-mm bull trout (0.39 ppm), 350-mm rainbow trout (0.12) and 300-mm mountain whitefish (0.25 ppm) from Carpenter Reservoir were positively correlated with fish size and were significantly higher than mercury concentrations of Seton Lake and Bridge River bull trout (0.10 ppm), rainbow trout (0.03 ppm) and mountain whitefish (0.04 ppm) of a similar size. The Seton Lake and Bridge River results are similar to or slightly less than concentrations that are typical for fish of this region of BC. Mercury concentrations of Carpenter Reservoir bull trout have not changed between 1988 and 2008 and suggests that the concentrations measured are fairly stable. Most other metals in fish were similar to or less than regional concentrations and did not show any trend within or between water bodies. The pattern of metals concentrations in water and in sediments indicates that metal concentrations in the Bridge River system are associated with fine sediments in depositional areas and are elevated primarily for those metals that are naturally elevated for this geologic region of BC as described above. The only exception is for mercury, which is elevated in Tyaughton Creek likely due to a natural source of cinnabar (Hg-S) upstream or possibly due to historical mining activities. 1.2 Management Questions The primary management questions addressed by the Bridge-Seton Metal and Contaminant Monitoring program are: 1) Will the new operation defined by Alternative N2-2P result in a change to the concentration/distribution of metals and other contaminants in the water and sediments of reservoirs and rivers in Bridge-Seton System? This question can be specifically related to: 1) the redistribution of metals and contaminants from Carpenter basin into the Seton basin; and 2) the impacts of the introduction of metals and other contaminants from Carpenter Reservoir into the Lower Bridge River. 2) If redistribution of metals and contaminants occurs, will this result in an increased bioaccumulation of metals and contaminants in fish in the Bridge-Seton system? Historic studies indicate that fish (bull trout, rainbow trout and mountain whitefish) from Carpenter Reservoir have significantly higher tissue mercury concentrations than the same species as in Seton Lake. This question relates to whether changes in operation ultimately will result in higher tissue mercury concentration in Carpenter Reservoir fish and whether this would extend to fish in Seton Lake. At this point in time, the focus of the studies is on metals, particularly mercury. However, if other contaminants such as PCBs or pesticides/herbicides are identified as potentially present in the system, these can be addressed as part of the routine monitoring program for water and sediment. BC Hydro Page 3

4 1.3 Detailed Hypotheses Regarding Impacts of Reservoir Operation on Metals and Contaminant Concentration in Abiotic and Biotic Components of the Ecosystem The fundamental question addressed by the monitoring program is whether implementation of the N2-2P operating regime will alter the concentration or distribution of metals and other potential contaminants in the abiotic (sediment, water) and biotic (fish) components of the Bridge-Seton system. The concerns have focused on three geographic areas within the Bridge River system and accordingly the monitoring hypotheses are: H 1 : Implementation of the chose alternative (N2-2P) will not increase metal concentration into abiotic or biotic components of the Carpenter Reservoir ecosystem. H 1a : There is no significant increase in the concentration of metals and contaminants in water H 1b : There is no significant increase in the concentration of metals and contaminants in sediment. H 1c : There is no significant increase in the concentration of metals and contaminants in fish tissue. H 2 : Implementation of the chose alternative (N2-2P) will not increase metal concentration into abiotic or biotic components of the Lower Bridge River ecosystem. H 2a : There is no significant increase in the concentration of metals and contaminants in water. H 2b : There is no significant increase in the concentration of metals and contaminants in sediment. H 2c : There is no significant increase in the concentration of metals and contaminants in fish tissue. H 3 : Implementation of the chose alternative (N2-2P) will not increase metal concentration into abiotic or biotic components of the Seton Lake Reservoir ecosystem. H 3a : There is no significant increase in the concentration of metals and contaminants in water. H 3b : There is no significant increase in the concentration of metals and contaminants in sediment. H 3c : There is no significant increase in the concentration of metals and contaminants in fish tissue. The decision to select Alternative N2-2P was in part due to the assumption that there would be no change in the concentration and distribution of metals and contaminants in the abiotic and biotic components of the Bridge River system. If this assumption is not valid, then further consideration of the impacts of changes in concentration and distribution need to be more fully studied and incorporated into the decisions about the preferred operating alternative for the system. BC Hydro Page 4

5 1.4 Key Water Use Decision Affected The water use decision influenced by this monitoring program is the timing of flow management among parts of the system, as it may affect the movement of metal and contaminants in sediment and water. 2 Monitoring Program Proposal 2.1 Objectives The Terms of Reference (TOR) for the investigation of water quality, sediment chemistry and fish health is dedicated to addressing the following three objectives: 1) Document water quality from a heavy metals contamination perspective, of important tributary streams and mainstem waterbodies including Downton Reservoir, Carpenter Reservoir, Bridge River, Seton Lake and Anderson Lake. 2) Determine sediment metals concentrations from the Bridge River system. Sediment samples were acquired in September 2011 from Downton Reservoir, Carpenter Reservoir, Seton Lake and Bridge River in approximately the same locations as were sampled in 2000 and Data from Anderson Lake will be attempted in These data will be compared to historic data to document any changes that may have occurred. Further sediment samples will be collected from strategic locations depending on the outcome of planning discussions. 3) Determine mercury and metals concentrations in fish tissue from bull trout (Salvelinus confluentus), mountain whitefish (Prosopium williamsoni) and rainbow trout (Oncorhynchus mykiss) from the above waterbodies. This work builds on the database established in 2000 and Consultation Prior to undertaking field work, the TOR will be discussed with the St át imc First Nation and BC Hydro to ensure that the field program addresses any outstanding concerns related to mercury and metals contamination in environmental media, especially water and fish. Ultimately, this monitoring program is dedicated to addressing concerns regarding human health. Thus, it is important that the field data be collected to address concerns of St át imc with respect to fish (species, size, location) and health of wildlife (drinking water, fish). We will be seeking input from elders and resource harvesters to gauge the historic and current level of concern in order that the field programs and data collected are sufficient to fully address all concerns. Part of this process involves communication and consultation to ensure that the community is fully aware of potential risk, if any in consuming local wildlife and fish from the Bridge River system. For example, migratory, anadromous salmon are a very important component of the diet of the St át imc people. It is important to communicate that metals and mercury are acquired from food. Because salmon do not eat during their long migration, they are not exposed to mercury or other contaminants in food and there should be no concern regarding the quality of this fish species as it relates to the Bridge system. 2.3 Approach The monitoring approach is to continue the general approach used during previous investigations. Periodic sampling of metals and contaminants in water, sediment and BC Hydro Page 5

6 fish tissue will provide the information to address the management questions. Given that there is a time lag between potential mobilization of metals/mercury in water and sediment and ultimately fish, the schedule of sampling activities will differ each year. Water will be collected seasonally each year whereas sediment and fish sampling will be conducted at 5-year intervals. Note that work by Aqualibrium (2000) and Azimuth (2008) concluded that water and sediment metals concentrations in Carpenter Reservoir and Seton Lake are elevated primarily for those metals that are typically elevated for this geologic region of BC (Rieberger, 1992a). These included arsenic, copper, chromium, cadmium and zinc with highest concentrations found in deep, depositional areas of these waterbodies and were associated with fine grain (silt/clay) sediment. It is important to note that there were no exceedences of metals (including mercury) in water or in sediments that were not also elevated in this region of BC (Rieberger, 1992a). These factors will be considered when planning and implementing the field program. Task 1 Project Coordination Project coordination involves the general administrative and technical oversight of the program. This will include but not be limited to: 1) budget management, 2) staff selection, 3) logistic coordination, 4) technical oversight in field and analysis components; and 5) liaison with regulatory and first nations groups. Task 2: Water Sampling Water samples will be collected each year during two time periods: during spring freshet and during summer low flows, to characterize high freshet and low water input periods. Water sampling stations will be situated in the same locations as established in the 2008 study: Downton Reservoir Tyaughton Creek Carpenter Reservoir downstream of Tyaughton Creek Carpenter Reservoir downstream of Marshall Creek at Nosebag Carpenter Reservoir upstream of intakes to Bridge GS Carpenter Reservoir upstream of Terzaghi dam Lower Bridge River upstream of the Yalakom River Additional water samples will be collected opportunistically and strategically as part of the larger program planned for the Bridge River system, such as from Cadwallader Creek. Standard Operating Procedures (SOPs) will be developed and provided to other field teams to facilitate collection of water samples using standard procedures, including Quality Assurance/Quality Control (QA/QC) measures. Details of the water sampling program will be finalized pending discussion with St át imc and BC Hydro to ensure that the critical objectives of the TOR are met and ensure that ecological and human health concerns are fully addressed. Water sampling methods will be similar to those outlined in the Azimuth (2008) report and will include temperature and oxygen profiles as well as the following chemical parameters: water hardness, conductivity, ph, total dissolved and suspended solids, dissolved anions and BC Hydro Page 6

7 nutrients (ammonia, alkalinity, chloride, silicate, sulfate, nitrate, nitrite, total Kjeldahl nitrogen, orthophosphate and total phosphate), organics (total and dissolved organic carbon), and total and dissolved metals concentrations and low level mercury and methyl mercury concentrations. Some of the water samples will be collected by crews under this program, and some may be collected by crews from other programs in these areas (BRGMON-1, BRGMON-3, BRGMON-4, BRGMON-7, and BRGMON-8) Task 3: Sediment Sampling Ultimately, sediments are a sink for water-borne particulate compounds, especially in deep areas such as the downstream, lacustrine zones of Carpenter Reservoir and very deep lakes such as Seton. Erosion of soils naturally elevated in certain metals (e.g., arsenic, cadmium, copper, zinc) typical of this geologic region of BC and/or released due to historic mining (e.g., mercury and perhaps arsenic in the Tyaughton Creek watershed) will become deposited and over time, buried. The pattern of sediment metals concentrations in Carpenter Reservoir since the initial 2000 investigation (Aqualibrium, 2001) and the 2008 survey (Azimuth, 2009) does not suggest that there has been any change in sediment chemistry due to reservoir operation. Sediment was collected from the same locations as in the Aqualibrium (2000) and Azimuth (2008) studies including Downton Reservoir, Tyaughton Creek, Carpenter Reservoir (4 locations), lower Bridge River and Seton Lake (3 locations). Sediment was not acquired from Anderson Lake in 2011 but will be obtained in Data will be compared to earlier data to establish a baseline prior to implementation of the N2-P2 scenario. Task 4: Fish Sampling Bull trout (Salvelinus confluentus), rainbow trout (Oncorhynchus mykiss) and mountain whitefish (Prosopium williamsoni) tissues were collected using nondestructive and destructive techniques (whitefish only) from Carpenter Reservoir, Seton Lake and the lower Bridge River in 2000 (whitefish and bull trout only) and 2008 for the analysis of mercury and other heavy metals. Mercury (and to a lesser extent, selenium) is the only metal that accumulates at increasingly higher concentrations within fish tissue and is the most important contaminant in fish with the potential to adversely affect animal and human health. Long-term monitoring of changes in tissue concentrations can help provide managers with information on whether operational changes have affected fish tissue metals concentrations, as well as providing essential data with respect to risk from dietary exposure to mercury by fish-eating wildlife and to humans. Fish capture and tissue/biopsy sampling of mountain whitefish, bull trout and rainbow trout from Carpenter Reservoir, Seton Lake Reservoir and the Bridge River will be conducted at five-year intervals (2012, 2017 and 2021) as per the 2008 survey. For efficiency, where possible tissue samples will be collected by concurrent fish sampling programs (BRGMON-1, BRGMON-3, BRGMON-4, BRGMON-7, BRGMON-8), following standard procedures provided by this program. To derive statistically comparable size-mercury relationships, approximately 25 specimens of each species (size-stratified) are required from each water body. However, the numbers of fish taken may be reduced if a decision is made to focus on capturing fish within a more discrete size range, such as the size most commonly consumed. BC Hydro Page 7

8 Task 5 Reporting Reporting will include: a) brief data report for each year that water samples are collected, b) analysis and reporting for each year that fish tissue samples are collected, and c) a synthesis report at the end of the 10-year program that outlines the findings from the program as they relate to the primary components described above. 2.4 Schedule The sampling and reporting schedule is described in the sections above. 2.5 Budget Estimated costs are $415, References Cited Aqualibrium, Carpenter Reservoir, Seton Lake and Bridge River Metals and mercury concentrations in fish and sediments. A report prepared for BC Hydro, Burnaby by Aqualibrium Environmental Consulting (now Azimuth), Vancouver BC. May pp. + App. Azimuth Environmental Consulting Bridge-Seton metals and contaminant monitoring program. A report prepared for BC Hydro, Burnaby BC by Azimuth Consulting Group, Vancouver BC March pp. + App. Azimuth Environmental Consulting. In prep. Bridge Seton Metals and Contaminant Monitoring Program: July December 2011 Draft Interim Results Summary. Rieberger, K Metal concentrations in bottom sediments from uncontaminated BC lakes. Ministry of Environment Lands and Parks. Water Quality Branch, August BC Hydro Page 8