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considerations mitigate in favor of a conservative approach to protecting future water supplies. <br /> Where existing water quality is adequate to protect this use, and in the absence of dischargers to <br /> these segments or testimony in opposition to such classification,the water supply use has been <br /> assigned because it is reasonable to expect that it may exist in the future in such cases. For <br /> stream segments that flow through, or in the vicinity of, municipalities,this conclusion is further <br /> justified, since there is a reasonable probability that the use exists or will exist. Where the water <br /> supply classification has been opposed, the Commission has evaluated the evidence on a site <br /> specific basis, and in many cases the classification has been removed. <br /> V. Water Ouality Standards--Generally <br /> 1. The water quality standards for classified stream segments are defined as numeric values <br /> for specific water quality parameters. These numeric standards are adopted as the limits <br /> for chemical constituents and other parameters necessary to protect adequately the <br /> classified uses in all stream segments. <br /> 2. Not all of the parameters listed in the "Tables" appended to the Basic Regulations are <br /> assigned as water quality standards. This complies with Section 3.1.7(c) of the Basic <br /> Regulations. <br /> Numeric standards have been assigned for the full range of parameters to a number of <br /> segments where little or no data existed specific to the segment. In these cases,there was <br /> reason to believe that the classified uses were in place or could be reasonably expected, <br /> and that the ambient water quality was as good as or better than the numeric standards <br /> assigned. <br /> 3. A numeric standard for the temperature parameter has been adopted as a basic standard <br /> applicable to all waters of the region in the same manner as the basic standards in Section <br /> 3.1.11 of the Basic Regulations. <br /> The standard of a 3 C temperature increase above ambient water temperature as defined <br /> is generally valid based on the data regarding that temperature necessary to support an <br /> "Aquatic Life - Class 1" fishery. The standard takes into account daily and seasonal <br /> fluctuations; however, it is also recognized that the 3 C limitation as defined is only <br /> appropriate as a guideline and cannot be rigidly applied if the intention is to protect <br /> aquatic life. In winter, for example, warm water discharges may be beneficial to aquatic <br /> life. It is the intention of the Commission in adopting the standard to prevent radical <br /> temperature changes in short periods of time which are detrimental to aquatic life. <br /> 4. Numeric standards for seventeen organic parameters have been adopted as basic <br /> standards applicable to all waters of the region in the same manner as the basic standards <br /> in Section 3.1.11 of the Basic Regulations. These standards are essential to a program <br /> designed to protect the waters of the State regardless of specific use classifications <br /> because they describe the fundamental conditions that all waters must meet to be suitable <br /> for any use. <br /> It is the decision of the Commission to adopt these standards as basic standards because <br /> the presence of the organic parameters is not generally suspected. Also, the values <br /> assigned for these standards are not detectable using routine methodology and there is <br /> some concern regarding the potential for monitoring requirements if the standards are <br /> placed on specific streams. This concern should be alleviated by Section 3.1.14(5) of the <br /> Basic Regulations but there is uncertainty regarding the interpretation of those numbers <br /> by other entities. Regardless of these concerns, because these constituents are highly <br /> toxic, there is a need for regulating their presence in State waters. Because the <br /> 10 <br />