Monitoring to Detect Changes in Water Quality Series (Proceedings of the Budapest Symposium, July 1986). IAHS Publ. no. 157,1986.

Transcription

1 Monitoring to Detect Changes in Water Quality Series (Proceedings of the Budapest Symposium, July 1986). IAHS Publ. no. 157,1986. Requirements of a water quality information system for New Zealand G. B. McBRIDE Water Qaulity Centre, Ministry of Works and Development, Private Bag, Hamilton, New Zealand ABSTRACT Two major, interrelated, potential impediments to the design of a water quality information system are identified; confusion over the meaning of the phrase "water quality"; and the lack of a clearly stated goal for water quality management. "Water quality" should refer only to the suitability of water for its desired uses, so that the goal simply is to promote and protect those water uses. The implications for the current design of a New Zealand national water quality information system, particularly concerning the choice of sampling sites and water quality characteristics, are addressed. INTRODUCTION The National Water and Soil Conservation Authority of New Zealand is the body charged by statute with setting national policy for water resources management. It has resolved recently to develop, in co-operation with the 20 Regional Water Boards that administer water management over New Zealand, a national water quality information system, to extend or augment existing regional monitoring systems and special surveys. Such a system is to allow the Authority to give account of its stewardship of water resources, and to provide national resource use planning statistics. It will be tied into existing hydrological and land data information systems, and will also enhance quality assurance programmes. It is appropriate to examine the information requirements of such a water quality information system before developing its detailed design. In so doing we have identified particularly the problems posed by confusion over the meaning of the phase "water quality", and by the lack of a clear goal for water quality management, as major potential obstacles for system design. This paper describes these problems, and indicates how we are proceeding with the design of a national water quality information system. The system must be designed to produce the maximum possible information for a given cost; the analytical and staff resources available in New Zealand are not substantial (the population of 3.5 million is spread over km 2 ), and must be used wisely. 29

2 30 G.B.McBxide EVOLUTION OF MONITORING PROGRAMMES The evolution of water quality information systems seems, from one country to another, to follow a pattern similar to that experienced in New Zealand (described in McBrideet al., 1985). First, generally in the 1950's and I960's, monitoring of a few water quality characteristics (e.g., DO, BOD ) is undertaken to attempt to define obvious pollution problems. Subsequently, this "problem definition" phase evolves into a "water quality management" phase, in which management techniques are implemented progressively (i.e., permits, grants, enforcement procedures, setting of receiving water standards, minimum effluent standards, water resource management plans) to provide for rational and fair allocation of water resources between competing uses. In this phase monitoring programmes must evolve also, to the point where their results can be used to assess the effectiveness of the management strategy. There is evidence to suggest that the evolution of water quality monitoring has not kept pace with the evolution of water quality management (e.g., National Academy of Sciences, 1977; General Accounting Office, 1981; Ward et al, in press). In the problem definition phase, monitoring programme design is relatively straightforward because the goal of such studies (e.g., to assess the effect of a sewage discharge on stream DO) is well defined. That is, the "why" of the monitoring is easily quantifiable. In the water quality management phase the goal of the monitoring is much more elusive, which appears to have resulted in the design of the programmes being focussed on the details of the "where", "when" and "what" to measure, but the "why" has often been acknowledged in only very subjective ways, leading to unrealistic information expectations (Ward et al., in press). We have inferred two major, interrelated, reasons for this uncertainty: ambiguity of the phrase "water quality", and the lack of a clearly stated goal for water quality management. THE MEANING OF "WATER QUALITY" Use of the phrases "water quality management" and "water quality monitoring" carry an implication to many that "water quality" is an objective universal quantity. For example, in a definitive Supreme Court of New Zealand decision on setting of receiving water standards (decision of Cooke J., 1976, 1 NZLR 1) "...existing water quality... investigation will have to be made to find it out" (emphasis added). But can "it" be defined objectively? We believe that the answer is no. It can mean different things to different people, and even one person's perceptions of quality may change through time. It seems that the human mind perceives water quality as being good if desirable water uses inure, and not good if they don't. This means that a particular concentration of some chemical dissolved in water may reflect either good or bad quality water. For example, a concentration of 2 parts per million boron in a river may not affect any present uses of the river, and the river water might be considered to be of good quality. However, if the water is

3 Water quality monitoring for New Zealand 31 subsequently required for regular irrigation of certain horticultural crops the boron concentration will be too high and the water may then be considered to be of poor quality (that will certainly be the irrigator's view). Furthermore, suppose a qualitative definition of water quality had been made before the horticultural development appeared, and that boron was not included in the definition (it is seldom monitored routinely). According to such a definition the quality of the river water may be good, yet unsuitable for a desirable use! In water resources literature there is now, perhaps belatedly, a recognition of the difficulties that this lack of definition imposes (e.g., General Accounting Office,'1981 ; Schroevers, 1983; van Belle & Hughes, 1983). There is an increasing consensus that "water quality" should be taken to mean the physical/chemical/ biological characteristics of water necessary to sustain desired water uses. This is the view promoted by James (1979) and Lee & Jones (1983): water quality refers to the suitability of water for its desired uses. This definition can never result in a universally applicable set of numbers, because measurements that need to be made to assess the suitability of water for one use are not the same as those required for another use, and not all potential uses can be foreseen. In any event we have only incomplete knowledge of all the measurements necessary to assess suitability for a particular use, and of the significance of the results of those measurements. We do the best we can, in the light of present knowledge and available expertise. CLEARLY STATED GOAL It is important that any successful management system should have a clearly stated goal. This is distinct from having objectives, in that a goal is a statement of intent that is always valid (it is what Massie (1971) terms a "principle"). Objectives can be in conflict, and these should be resolved by the implementation of plans and policies which are formulated in the light of the goal. For example, objectives of providing on the one hand for the needs of primary and secondary industry, and on the other hand for water contact recreation, can be in conflict. A clearly stated goal guides the formulation of plans and policies to resolve the conflict. The water law - the 1967 Water and Soil Conservation Act, which is now being redrafted - has many admirable provisions (e.g., coverage of the whole country by 20 regional water boards, with boundaries coincident with river basin boundaries; a uniform system of water rights for taking, damming and discharging into waters), and can be interpreted to state three, possibly conflicting, goals. These are: (a) to promote conservation and best use of water; (b) to maintain and improve water quality; (c) to protect and preserve in their natural state those waters with high amenity value. We are concerned to resolve any possible conflict between these before recommending a detailed system design. Goal (a) suffers from the lack of definition of the word "conservation". If it is interpreted as being synonymous with

4 32 G.B.McBride "preservation", it will conflict with the promotion of best uses (since a change in water use often causes a change in water quality characteristics). If "water quality" in goal (b) is interpreted as an objective universal quantity (and, as noted above, it is so regarded by many, including those in the legal profession) then it will not be seen to have been maintained or improved when some new land-use or point source discharge is permitted. More particularly, for the purposes of this paper, the design and operation of routine water quality monitoring programmes under these two goals will be quite different, as summarised in Table 1. TABLE 1 Implications of two alternative goals for design and operation of a routine water quality monitoring system GOAL (= ITEM (a) Promote conservation and best use of water "why") (b) Maintain or improve water quality Information needed for design Information expected from operation Objective definition of all "best uses", their water quality requirements and "compliance". Compliance with standards for those uses. Objective definitions of "water quality", "maintain", and "improve" Changes in that water quality over time. Design - Sites tend to be Criteria* concentrated where water use conflicts are anticipated. - Characteristics related to water quality requirements of all desired uses. - Frequency related to definition of "compliance". Reporting - Goal met when probability of violation of water quality requirements in acceptable range. Sites "representative", and spread uniformly. Characteristics determined by definition of "water quality". Frequency related to trend detection power Goal met when trends are absent or improving. Sites "Where"; Characteristic H What" (e.g., ph, BOD invertebrates, ); Frequency = "When"

5 Mater quality monitoring for New Zealand 33 Of particular note is the way the two goals affect the choice of sampling sites and water quality characteristics (development of appropriate sampling frequencies is well understood, with a voluminous literature). Under goal (a) sites will tend to be concentrated in regions of present or anticipated conflicts of use and characteristics will be related to standards for water use protection, while under goal (b) sites will tend to be spread uniformly in space and characteristics selection will be somewhat arbitrary (and probably excessive). Goal (c) is clear enough, though not applicable to all water bodies. The apparent conflict between these goals can be resolved. By defining "water quality" as referring to the suitability of water for its desired uses, and by equating "conservation" with promoting best uses of water, goals (a)-(c) can be harmonized into a simple statement: (d) to promote and protect desirable water uses. The uses can be defined to include the functioning of aquatic communities. This goal deliberately excludes notions of "maintain or improve", precisely because a goal must always be seen to remain valid. It refers to all waters, not just some as with goal (c). Also, use of the word "desirable" carries the implication that indicative water resource management plans will have to be formulated (this is becoming common practice in New Zealand)in the light of the public's desires for water use. IMPLICATIONS FOR IDENTIFYING INFORMATION REQUIREMENTS Present proposals to amend the New Zealand Water and Soil Conservation Act are likely to result in a goal statement similar to (d), above. This will be used to guide the design of the future national water quality information system, which will initially be confined to inland surface waters. Location of sites Under goal (d), sites will neither be uniformly distributed, nor will they all be concentrated in regions of anticipated conflicts of use (the two extremes in Table 1). This is because some information will be required from sites not subject to conflicts of use, but for which it is desired that they be kept in their natural state (i.e., goal (c)). For rivers where use conflicts are anticipated, we envisage two sites; one upstream and one downstream of the conflict area. Recommendations for site location on lakes are being formulated in a forthcoming Lake Manager's Handbook. It is possible that nationally about 100 sites will be involved, that is an average of 5 sites per regional water board area. (This is in addition to the wide range of sites currently monitored as part of regional water resources management.) Selection of water quality characteristics Some desired uses are common to all sites, such as maintenance of aerobic aquatic communities, aesthetic enjoyment, and prevention of

6 34 G.B.McBride undesirable growths. Thus, from goal (d), the following characteristics will be measured regularly at every site: DO, BOD, ph, conductivity, TN, TP, SS, Hazen colour, turbidity (formazin), Secchi disk depth (lakes only). It should soon be possible to assess hue by matching with Munsell colour charts_ We hope to include some biological characteristics relevant to those uses - benthic invertebrates, chlorophyll-a (lakes only) and macrophytes, for which standard procedures are already available (Biggs et al., 1983) and are in use (Pridmore and Cooper, 1985). Some measurements of major ions will need to be made, but not on every occasion. Conductivity serves as an adequate surrogate for ionic strength. At some sites particular uses (e.g., industrial waste discharges) may be important and require that more specific characteristics be measured. In general, pollution from heavy metals and toxic elements is not widespread in New Zealand. The possible inclusion of bacteria (coliforms and faecal coliforms ) under review; their substantial and unpredictable variability in both time and space may mean that little useful information could be gained from routine networks. CONCLUSIONS Adoption of the goal of promoting and protecting desired water uses is (hopefully) going to result in a cost-effective design for a water quality information system, in that it ties down the selection of sampling sites and water quality characteristics to uses that are desired to be maintained (or avoided, in the case of nuisance growths). It thus clarifies the information requirements of a water quality information system. ACKNOWLEDGEMENTS R.C. Ward, R.D. Pridmore, D.G. Smith, R.J. Davies- Colley & M.E.U. Taylor contributed ideas for this paper. REFERENCES Biggs, B.J., Gifford, J.S. & Smith, D.G. (1983) Biological methods for water quality surveys. Water and Soil Miscellaneous Publication No. 54, Ministry of Works and Development, Wellington, New Zealand. General Accounting Office (1981) Better monitoring techniques are needed to assess the quality of rivers and streams. US General Accounting Office Report No. CED-81-30, Washington, D.C. James, A. (1979) The value of biological indicators in relation to other parameters of water quality. In: Biological Indicators of Water Quality (A. James and L. Evison, eds.), John Wiley & Sons, N.Y., Lee, G.F. & Jones, A. (1983) Active versus passive water quality monitoring programs for wastewater discharges. J. Wat. Pollut. Control Fed. 55(A), Massie, J.L. (1971) Essentials of Management. 2nd éd., Prentice- Hall, Englewood Cliffs, N.J.

7 Water quality monitoring for New Zealand 35 McBride, G.B., Smith, D.G. & Pridmore, R.D. (1985) Water quality monitoring in New Zealand. Wat. Qual. Bull. 10(2), National Academy of Sciences (1977) Analytical studies for the US Environmental Protection Agency: volume IV, environmental monitoring. National Academy of Sciences, Washington, D.C. Pridmore, R.D. & Cooper, A.B. (1985) Biological monitoring in freshwaters: proceedings of a seminar, Hamilton, November 1984, Parts 1 and 2. Water and Soil Miscellaneous Publication Nos.82 and 83. Ministry of Works and Development, Wellington, New Zealand. Schroevers, P.J. (1983) The need of an ecological quality-concept. Environ. Monit. & Assessment 3(3/4), van Belle, G. & Hughes, J.P. (1983) Monitoring for water quality: fixed station versus intensive surveys. J. Wat. Pollut. Control Fed. 55(4), Ward, R.C., Loftis, J.C. & McBride, G.B. (in press) The "data-rich but information-poor" syndrome in water quality monitoring Environ. Mgmt.

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