The Ministry of Environment Lands and Parks, Water Management Branch, (i.e., Water Quality Section) has identified the need to upgrade existing water quality guidelines (WQG) for temperature to protect water uses in British Columbia. A key requirement of this review was the need to replace narrative statements for some water uses in the existing guideline with numerical values derived for practical application. Water uses include drinking water, recreation and aesthetics, aquatic life (freshwater and marine), wildlife, industrial and agriculture (both irrigation and livestock watering). The intent of this initiative is to develop a guidance document that will safeguard water quality from a variety of human activities that could lead to adverse temperature effects on specific uses in aquatic environments throughout the province. Although generic in nature, the recommended guidelines are further intended to provide a baseline for setting water quality objectives within specific aquatic environments where extraordinary natural resource values warrant special consideration.
The nature of any adverse effect of human activity on water quality will depend on both temporal and spatial scales of that activity relative to the size of a given watershed, water body or receiving environment. To this end, adverse temperature effects may arise from a single activity or reflect a cumulative outcome from a variety of activities over a much larger geographical area. Similarly, a variety of guideline recommendations for individual water uses may be easily derived or difficult to establish, depending upon ecosystem complexity or the social, economic and cultural needs of society. The challenge, then, is to provide realistic measures of protection to each water use, in the face of burgeoning water and land-based developments and global climatic change, at a provincial scale.
A difficulty within the guideline development process concerns the trade-off between maximizing benefits and minimizing impacts of competing uses. The guideline could range between the extremes of full protection and full utilization of each use. There is little doubt that maximizing all designated uses will impose conflicting impacts on certain uses that cannot tolerate wide temperature variation. A further challenge, then, is to reach a balance that does not compromise resource values yet offers some flexibility for individual uses.
The purpose of this report is to review and incorporate recent literature related to temperature that will add to or improve on the current BC guidelines; applicable changes should focus on environmental conditions and organisms specific to the province of British Columbia.
In that context, the terms of reference for the work were very specific, requiring only the most recent updates in the literature. To this end, the last ten years was considered most relevant, although some papers back to the early 1970's were reviewed, where appropriate. In the review, it was recognized that the foundation of the existing BC guideline and those of most other jurisdictions, along with much of our understanding of temperature effects on fish in general, are based on the early work of Brett (1952; 1956) and others (e.g., Fry 1947; 1967). Rather than re-examining these works, the goal was is to expand on the most recent information that would improve the overall knowledge base.
The review also explored guidelines used by other jurisdictions in Canada and the United States. The intent was to develop a document with guideline recommendations supported, in part, by the expertise and knowledge that has been developed in other jurisdictions to effectively protect water uses from adverse effects of temperature from a variety of human activities. Numerical values to establish temperature maxima and minima for individual uses were considered where feasible.
It is important to note that temperature plays an important role in the response of aquatic organisms to a wide range of physical, chemical, and biological stresses. For example, increasing temperature accelerates the rate of uptake of chemical toxicants through increased cardiovascular and respiration function. Elevated temperatures increase the oxygen demand for most aquatic organisms while at the same time reducing the availability of dissolved oxygen in the environmental water. High water temperature degrades the ability of organisms to cope with swimming demands, while compounding the effects of biological stresses such as predation and disease. When dissolved gas supersaturation is present, accompanied by elevated temperatures, the effects of gas bubble trauma in fish are much more severe (Nebeker et al.. 1979, Birtwell et al 2000). These factors, while associated with temperature, cannot all be dealt with explicitly in this document. Such a task would essentially involve developing individual water quality guidelines for each stressor with temperature as an ancillary factor. The Province of British Columbia, the Canadian Council of Resource and Environment Ministers (CCRME - 1987), and the Canadian Council of Ministers of Environment (CCME - 1999) have developed guidelines for a wide range of chemical and physical stressors (see Section 1.1) and the effects of temperature are incorporated into those guidelines. Therefore, this guideline upgrade will examine the effects of water temperature on aquatic organisms in the absence of other physical and chemical stress issues.
Finally, this work identifies future research needs and presents data gaps, as well as provides guidance on the most appropriate temperature monitoring methods (i.e., sampling protocols) to assess compliance with the recommended guidelines.
1.1 Background
Water quality guidelines to assess
water quality problems or manage competing uses of water resources in inland
waters were initially developed on behalf of the Task Force for Water Quality
Guidelines for the Canadian Council of Resource and Environment Ministers (CCRME)
in 1987.
The guidelines were developed for use by Canadian provincial, territorial and
federal agencies to establish certain protective guidelines that were relevant
to Canadian conditions; guidelines that were considered general in nature and
subject to modification where local conditions dictated. Water uses considered
at that time included drinking water, recreation and aesthetics, freshwater
aquatic life, industrial and agricultural uses. Updates to the initial document
have occurred since 1989 as information on the effects of particular water quality
indicators have become available to support recommendations that minimize adverse
effects on specific uses.
The most recent guideline document was issued in 1999 on behalf of the Canadian Council of Ministers of the Environment (CCME). With respect to temperature, the most recent guidelines have been expanded to include the marine environment.
Canadian water quality guidelines have been formulated on the basis of the effects of water quality indicators on specific uses reported in the scientific literature. With respect to aquatic life, a number of protocols (i.e., minimum data set requirements and standards for toxicity testing) have been adopted to facilitate the guideline development process.
Following an extensive literature review of the properties, effective concentration and toxicity of a selected indicator, the guideline derivation approach considers all trophic levels of the aquatic ecosystem where data are available. The protection of all life history stages for all forms of aquatic life is a key element of the derivation process, and for most indicators a single maximum value is recommended based on a long-term no-effect concentration (i.e., the lowest-observable-effects level (LOEL) from a chronic exposure study using a non-lethal endpoint for the most sensitive life stage of the most sensitive aquatic species investigated (CCME 1999)).
In the absence of this information, acute exposure data have been substituted by adjusting short-term median lethal (LC50) or median effective (EC50) concentrations to long-term no-effect concentrations. When available, acute/chronic ratios (ACRs) are employed by dividing the median lethal or effective concentration by the no-observed-effect level (NOEL). When ACR's are unavailable, guidelines are derived from acute short-term study data by applying a universal application factor (AF) to each value (i.e., 0.05 for non-persistent variables and 0.01 for persistent variables (CCME 1999)).
Protocol procedures, however, recognize certain limitations that hamper guideline utility (CCME 1999). Data are seldom available to generate guidelines for all species present in the receiving environment. Extrapolation of toxicological data from one species to another may not reflect actual differences in sensitivities between species and, hence, may generate guidelines that are incapable of providing adequate protection for all species. Similarly, the extrapolation of laboratory results to natural aquatic ecosystems may not be truly representative of the expected response of individual organisms due to existing background environmental conditions (i.e., potential cumulative effects of physical and chemical constituents), acclimation processes or the population dynamics of representative biota (i.e., compensatory processes in the wild).
To date, the Ministry of Environment, Lands and Parks in the Province of British Columbia has adopted water temperature guidelines for drinking water and recreation provided by Health and Welfare Canada (BCMOELP 1998) and included additional working criteria for the protection of aquatic life in freshwater (Nagpal et al.. 1998). Of the specified uses identified above, the development of guideline information for the protection of aquatic life should receive the highest degree of scrutiny, given the more serious implications of water temperature fluctuations and extremes on aquatic biota.
Relative to this document, the selection of salmonid fishes as sentinel species in freshwater environments is intended to provide an acceptable benchmark for the protection of all aquatic life forms within distinct trophic levels. The use of salmonids as indicator species of ecosystem health is encouraged given their economic and recreational value province-wide. The development of temperature guidelines within an ecosystem context is intended to provide criteria that are compatible with ambient temperature regimes and the native fish complex. Water uses other than aquatic life are not expected to be seriously affected by a guideline that recognizes fisheries resources as the most sensitive use.
Beyond the protocols established in the CCME document, this report will attempt to address the effects of rate of temperature change on life history stages, in addition to identifying acceptable temperature maxima or minima for specific life history stages of individual species.
1.2 Literature search
The primary database search was conducted with the assistance of the National Research Council, Canadian Institute for Scientific and Technical Information (CISTI). The following resources were consulted during the water temperature search: Aquatic Sciences and Fisheries Abstracts, Biosis Previews, CAB Abstracts, EI Compendex, Enviroline, Oceanic Abstracts, Pollution Abstracts, Water Resources Abstracts, and Waternet. Information sources available through government services included the British Columbia, Ministry of Environment, Lands and Parks library catalogue, the British Columbia, Ministry of Environment, Lands and Parks web site, the Canada Department of Fisheries and Oceans library catalogue, the United States Environmental Protection Agency (EPA) library catalogue and the United States Environmental Protection Agency web site.
In addition, a request for current guideline information and supporting documents was issued to provincial agencies across Canada, as well as federal agencies (Environment Canada). EPA surface water quality standards for individual states in the Pacific Northwest (Washington, Idaho, Montana, Oregon and Alaska) were also reviewed at their respective web sites. A request for information was also sent to the Department of the Environment, Transport and the Region of Great Britain.
1.2 Definitions
For the sake of clarity, the following definitions are provided for specific terms used in this document (after MacDonald et al.. 1992):
a) Criteria - scientific data that are evaluated from specific studies designed to establish the lethal limit of a given parameter on a particular species or life stage (e.g., maximum upper tolerance temperature of developing rainbow trout embryos.
b) Guidelines - recommended numerical concentrations or narrative statements to protect specific water uses (e.g., no measurable change from natural conditions; lakes)
c) Objectives - numerical concentrations or narrative statements established to protect specific water uses at a specified site (e.g., 2.2 degrees C change; maximum increase for receiving waters)
d) Standards - objectives that are enforceable within environmental control laws of a level of government (e.g., 15 degrees C; maximum; for food processing)