Lakes and Watercourses

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y the environmental quality aspects each parameter is primarily intended to indicate and factors that have been deemed essentially ”good” or ”bad” in this respect. Assessing deviation from reference values is generally less of a problem than assessing current conditions. Increasingly pronounced deviation from the reference value, ie, from a natural state, is usually regarded as negative. Here too, therefore, class 1 represents the most favourable conditions and class 5 the least favourable. Once again, the assessment is made in the light of the quality aspects the respective parameters are primarily intended to reflect. Growing deviations may be favourable from other perspectives, which should be borne in mind when using the scales. The boundaries between classes are such that the classes might be perceived to overlap. However, when entering recorded values account should be taken of the way the threshold for the highest or lowest class has been expressed. Hence, (2.0 for class 1 and 2.0 – 5.0 for class 2 (chlorophyll concentration in lakes) means that a readings of 2.0 should be entered in class 1 and a reading of 5.0 in class two, and so on. Reference values The reference values have been arrived at in different ways for different parameters, depending on the availability of data. In some cases it has been possible to use the reference stations in the Swedish National Environmental Monitoring Programme. In others, collated data from environmental monitoring or from specific studies has been used, usually having eliminated stations considered to be affected. As regards fish, calculations have been made using national or supra-regional data bases in their entirety. Thus, these reference values represent the mean situation in Swedish lakes and watercourses across the country or for different types of lakes and watercourses. It has not been considered possible to identify pristine waters. Finally, it has not been possible to set reference values for some parameters at all. Here, assessments can only be made using a state scale (current conditions). In general, it has only been possible to a limited extent to give instructions on reference values specific to a given lake or watercourse, ie, on the way in which reference values for a particular lake or watercourse can be determined in the light of its position and other surrounding factors. Further work on development of calculation models is needed in this field. In the absence of such methods, reference values have been calculated statistically for regions (see next chapter) or groups of lakes/watercourses, eg, different types of lakes. The accuracy of these values varies and the assessment should be made with this in mind and in the light of the factors and conditions presented in the relevant background report 17
(in Swedish with English summary). The method of identifying reference values is explained in each chapter. In general, it may be said that further systematic studies are needed for most parameters in order to obtain representative data. It was proposed in the previous quality criteria for lakes and watercourses (Swedish EPA 1991) that county administrative boards and water management associations should compile maps on background conditions by catchment based on results from earlier surveys and studies of unaffected lakes and watercourses or using specified calculation algorithms. This is still to be recommended and would probably allow better adjustment to local or regional conditions than direct application of the reference values presented here, which are often regional and statistically based. Division in type areas Since available data varies greatly from one parameter to another and since various surrounding factors are significant to each parameter, it has not been possible to classify geographical regions and water types on the basis of principles common to all parameters. The various classifications are described in each chapter. References Swedish Environmental Protection Agency (1991): Bedömningsgrunder för sjöar och vattendrag (”Quality criteria for lakes and watercourses”). Swedish EPA General Guidelines 90:4. 18
Page 1 and 2: Environmental Quality Criteria - La
Page 3 and 4: TO ORDER Swedish Environmental Prot
Page 5 and 6: Reference Group Mats Bengtsson, Swe
Page 7 and 8: Summary This report on lakes and wa
Page 11 and 12: included. In addition to a large nu
Page 13 and 14: ased estimates are used. Given that
Page 15 and 16: TABLE 1. SUMMARY of parameters incl
Page 17: 16 The current conditions scale in
Page 21 and 22: conditions for watercourse flora an
Page 23 and 24: show the availability of nitrogen i
Page 25 and 26: Mean concentration of total phospho
Page 27 and 28: TABLE 9. DEVIATION from reference v
Page 29 and 30: Comments Classifications must be ba
Page 31 and 32: winter/spring, i.e. ice-covered per
Page 33 and 34: Light conditions Introduction Light
Page 35 and 36: TABLE 13. CURRENT CONDITIONS: turbi
Page 37 and 38: Acidity / acidification Introductio
Page 39 and 40: industrial pH). The change in acidi
Page 41 and 42: The pre-industrial concentration of
Page 43 and 44: very high degree of reliability and
Page 45 and 46: TABLE 19. CURRENT CONDITIONS: metal
Page 47 and 48: TABLE 22. DEVIATION from reference
Page 49 and 50: TABLE 24. (continued) Cu Zn Cd Pb C
Page 51 and 52: Swedish EPA (1993): Metals and the
Page 53 and 54: Assessment of current conditions TA
Page 55 and 56: TABLE 29. CURRENT CONDITIONS: poten
Page 57 and 58: TABLE 32. DEVIATION from reference
Page 59 and 60: References Cronberg, G., Lindmark,
Page 61 and 62: (see Appendix 1). If submerged and
Page 63 and 64: References Andersson, B. (1998): Va
Page 65 and 66: The genera in question and their tr
Page 67 and 68: Benthic fauna Introduction Benthic
Page 69 and 70:
TABLE 41. CURRENT CONDITIONS: botto
Page 71 and 72:
Comments The assessment must be bas
Page 73 and 74:
has yielded better results than did
Page 75 and 76:
TABLE 45. CURRENT CONDITIONS: fish,
Page 77 and 78:
TABLE 46. DEVIATION from reference
Page 79 and 80:
TABLE 48. DEVIATION from reference
Page 81 and 82:
TABLE 48. (Contd.) Proportion of al
Page 84 and 85:
Presentation of data When using the
Page 86 and 87:
APPENDIX 1 Ceratophyllum demersum 1
Page 88 and 89:
APPENDIX 2 Calculation of index and
Page 90 and 91:
APPENDIX 2 Table 1b. Indicator gene
Page 92 and 93:
Genus Indicator value -------------
Page 94 and 95:
APPENDIX 2 45 Planorbis sp. 46 Anis
Page 96 and 97:
APPENDIX 2 214 Leuctra hippopus 215
Page 98 and 99:
APPENDIX 2 384 Tinodes waeneri 385
Page 100 and 101:
APPENDIX 2 (6) O/C index (Wiederhol
Page 102 and 103:
APPENDIX 3 Dace Stäm Leuciscus leu
Page 106:
REPORT 5050 Environmental Quality C
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Lakes and Watercourses

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