Measuring the Health of our Rivers
Issue from the Journal "Water"
N J Schofield, P E Davies
Reproduced with permission of the Australian Water Association, May/June 1996
- What is River Health?
- Why Measure River Health?
- Assessment Methods
- RIVPACS Development
- Technical Issues
- Complementary Approaches
- Future Development
Peacock Creek NSW
The state of river ecological health is a key issue in land and water management. Measurement of physico-chemical parameters alone does not allow an assessment of the biological condition of surface waters. Assessing the health of Australia's rivers requires a nationally consistent, scientifically valid methodology based on standardised comparative sampling of biological communities and/or processes. The application of the river invertebrate prediction and classification scheme (RIVPACS) to Australian conditions, funded under the National River Health Program (NRHP), is a major attempt to develop such an approach. It is based on the concept of comparison of macroinvertebrate community composition between a site and a set of regionally relevant 'least disturbed' reference sites. This is the first time a tool has been developed for monitoring the ecological health of rivers at a local, regional or national scale. Other similar tools are being developed in the NRHP using community data for fish, algae, and macrophytes, as well as for key ecological processes. These tools are specifically aimed at providing managers with information on the effects of land and water management on river ecological condition. The NRHP is set to deliver the capability to perform the first national assessment of river health by mid-1997, though the future of the program depends on Commonwealth funding for four years beyond 1996.
River health, bioassessment, monitoring, RIVPACS, ecology, macroinvertebrates, water quality, fish, diatoms, phytoplankton
In 1993 the Commonwealth launched an ambitious program to develop scientifically based tools to assess and monitor the health of the nation's rivers. This was in response to growing community concern about the ecological condition of the country's most vital resource: water. The massive outbreak of blue-green algae on the Darling River in 1991 focussed the community's attention on the widespread degradation of our rivers. These concerns have been exacerbated by reports of fish kills, declining native fish populations, toxic algae, infestation by exotic species, restricted recreational access and declining drinking water quality.
Underpinning these concerns is the frustration associated with the absence of a clear, accurate picture of the condition of our rivers. The community wants to know: Just how many pristine rivers remain? What is the health of rivers in our developed landscape? (and most importantly) What can be done to protect and restore Australia's remarkable river ecology? These questions can only be answered with a nationally consistent, scientifically based river health assessment methodology.
Water quality measurement
The term 'river health' is a useful and widely understood concept. However, it is difficult to describe in precise scientific terms. In this paper, river health is taken to mean the degree of similarity to an unimpacted river of the same type, particularly in tens of its biological diversity and ecological functioning. This rather simplistic definition says little of the attributes or behaviour that we might expect of a healthy river but has the advantage of a verifiable, regionally relevant scale against which to measure health. In fact, this is analogous to a general assessment of human health.
In Australia, relatively few rivers remain in an unimpacted or pristine state. Most rivers are affected by a number of instream, riparian and catchment modifications or practices. This often results in them being less biologically functional and of lower ecological value than their original states. Important river stresses include nutrient enrichment, increasing salinity, pesticides, sediment loading, water extraction, flow controls, loss of riparian vegetation and effluent discharge.
To understand why we are interested in measuring river health, it is first necessary to appreciate our changing perceptions of the values and appropriate uses of rivers. In the 200 years since European settlement of Australia, the principal uses of rivers have been navigation, drinking water, irrigation water, effluent disposal and recreation. These uses are of high social and economic value.
More recently, the environmental movement has stimulated the widespread appreciation of the natural and ecological values of rivers through such concepts as 'wilderness' and 'biodiversity'. This has been (at least partially) more formally encapsulated by Australian governments adopting the principles of ecologically sustainable development (ESD). However, inappropriate land use and instream practices have led to a continued decline in the social, economic and environmental values of our rivers.
In the ecological context, rivers in Australia have four major management needs:
- protecting and conserving the remaining pristine rivers and pristine river reaches across as many river types as possible;
- protecting riverine endangered species and ecosystems of high conservation value;
- applying ESD principles to new developments which might affect rivers; and
- rehabilitating degraded rivers to acceptable levels of river health.
One of the first steps in achieving these objectives is to:
- provide feedback to river managers, community groups and the community at large on the current and changing status of river health;
- identify and predict specific impacts and their causes or sources;
- identify reaches of high conservation status requiring protection; and
- demonstrate the effectiveness of management actions aimed at improving the quality of rivers.
Assessing the condition of rivers Australia has had a long and varied history. It has involved two principal approaches: physio-chemical monitoring and qualitative 'state of the rivers' descriptions. While both approaches have produced some useful results, they have generally failed to provide a consistent and comprehensive assessment of river condition either regionally or nationally, and have said little about the ecological state environmental quality or rivers.
Moreover, they have been unable reliably assess the impacts of various instream and catchment practices on river ecosystems or provide reliable answers to management questions in a cost-effective way that can also be understood by the community. The preoccupation with chemical water quality has also largely overlooked structural impacts that have led to alterations to river flow regimes, loss of habitat area, loss of habitat diversity, obstructions to passage through streams and riparian degradation (Harris 1995).
A recent review of water quality monitoring Australia (EPA 1995) identified about 1800 current water quality monitoring programs costing about $100 million pa. This analysis of monitoring practices led to the following key recommendations:
- redistribute funding within programs to emphasise improved planning, design, use of field analyses and reporting information to the community, at the expense of laboratory analyses;
- increase collaboration between organizations to reduce duplication and improve information flow;
- increase analysis and reporting from long-term data sets; and
- increase community involvement.
'State of the Rivers' assessments have been undertaken in Victoria, NSW, Queensland and Western Australia. These assessments each use different methods and are essentially descriptive in nature. They attempt to incorporate a range of variables and components (eg water quality, channel form, riparian condition) and summarise these data into a single assessment of condition.
Typically, there is little biological information in such assessments. Some are catchment-based and have the potential to work well with integrated catchment management. However, one of the main problems in these assessments is the lack of a local, regional or national reference against which to judge the results. This does not allow recognition of inherent differences in river form and condition that can occur given differing geomorphology, stream size etc.
The case for using bioassessment techniques to measure river health is principally two-fold:
- assessing ecological values requires direct measurements of the system; and
- physico-chemical measurements alone are inadequate for assessing river health, as the processes linking changes in physical and chemical conditions in rivers and the ecological state are either poorly understood or too complex. They also do not take into account important changes to river habitat and are frequently instantaneous.
The integration of regionally referenced physical, chemical and biological measures is needed to provide comprehensive, sensitive assessment of river condition. The biological measures can involve a wide range of groups including macroinvertebrates, fish, algae, diatoms, microorganisms and macrophytes. Each group reflects environmental stresses in different ways and can be used to assess river health. They have the potential to provide an integrated response to a number of stresses as well as measures over different time-scales. Selective responses to particular stresses at the group, taxon and species levels can help identify specific sources of stress (eg a particular type of chemical pollution or change in habitat structure).
The adoption of biological methods has been slow in Australia, partly reflecting the culture, skills and knowledge bases of Australian water managers. However, their acceptance is improving (Norris and Norris 1995) as a result of improved standardised protocols, more cost-effective, rapid bioassessment tech-niques, simplified presentation of the results, and the growing demand for direct measures of ecosystem health.
Monitoring the time trends of individual river parameters or periodic descriptions of river characteristics are not in themselves sufficient to assess and monitor the condition and health of rivers. A methodology is required to measure 'health' against an appropriate, regionally based scale. The only methodology that has attempted, and largely achieved this to date, whether physical, chemical or biological, is RIVPACS, the River Invertebrate Prediction and Classification System.
This approach is based on comparing monitored river sites against reference unimpacted, or least impacted sites. This gives a measure of the degree to which an impacted site retains the biological quality it would have had if undisturbed. also allows prediction of the biotic community anticipated at a site if it was undisturbed. RIVPACS was developed using macroinvertebrate fauna but the same principles can be applied to other faunal groups.
The development of RIVPACS started at the River Laboratory of the Institute of Freshwater Ecology, UK in 1977. The first project had two objectives:
- to develop a classification of unpolluted running water sites based on macroinvertebrate fauna (seen relevant to the conservation of biological examples of the full range of river systems in the UK)
- to determine whether the fauna to be expected at an unstressed site could be predicted from physical and chemical features only (seen as the first stage in the new challenge of attempting to develop prediction system for detecting and assessing environmental impact at stressed sites, Wright 1995).
The decision to use macroinvertebrates rather than other faunal groups was based on the moderate richness of the macroinvertebrate fauna throughout the country , the availability of good taxonomic keys and the extensive literature on the response of many taxa to a range pollutants. Biologists in the UK water industry were also highly familiar with the macroinvertebrate fauna.
The project, based on 268 sites on 41 river systems, commenced with a four year program to determine the feasibility of a prediction system. During phases two and three (six years) the first version RIVPACS I was developed, based on 370 sites and 61 rivers.
By 1989-90, an upgraded RIVPACS II version, based on 438 sites and 80 rivers and incorporating a new classification and prediction system, was completed for operational use in the 1990 UK River Quality Survey. The most recent and advanced version, RIVPACS III, based on 700 sites, was used in the 1995 UK River Quality Survey.
In the Prime Minister's Environment Statement, in December 1992, about $7m was allocated to support the development of integrated physical, chemical and biological monitoring of Australia's rivers. The funds were allocated to the Commonwealth Environment Protection Agency (CEPA), who divided the funds between State/Territory projects, R&D and a water quality review (CEPA 1995).
A national call for project proposals was made in March 1993 but this did not provide an adequate framework for a national program. About this time, discussions took place with the Land and Water Resources Research and Development Corporation (LWRRDC), who were also planning to establish a national rivers program. In June the two organisations formally established an agreement to run a joint program, with LWRRDC providing the R&D management support. A program management committee was formed with two members each from LWRRDC, CEPA and DEST, to be later joined by two members from the Urban Water Research Association of Australia (UWRAA).
The management committee recognised the need for a program framework with clear national objectives and used a workshop organised by the University of Canberra ('Use of Biota to Assess Water Quality', September 1993) to help identify program priorities. A session was devoted to proposals from the states and territories. Presentations on RIVPACS at the workshop led to its subsequent adoption by the management committee as a national framework for river health monitoring. This constituted a change in direction but has subsequently been widely accepted amongst state and territory agencies and the research community.
Following the September workshop, the National River Health Program (NRHP) was formed and the management committee appointed a program coordinator with expertise in river assessment. A detailed program (Figure 1) was quickly assembled and the commissioning of projects commenced. Details of the program structure, funding, R&D and of RIVPACS can be found at the NRHP world wide web home page at the following address (or URL): *http://www.erin.gov.au/portfolio/epa/nrhp/index.html and is described in NRHP (1997). The philosophy was to develop RIVPACS through the state/territory monitoring program; to conduct a number of supporting R&D projects to both enhance the RIVPACS methodology and address some specific issues regarding its application to Australian conditions; to conduct projects on the development of alternative but complementary approaches (using similar principles including the essential RIVPACS methodology) for other groups (fish, algae, diatoms, microorganisms, macrophytes), and provide support for macroinvertebrate taxonomy. The latter is seen as a key hurdle in further developing RIVPACS using macroinvertebrates.
One of the first tasks of the coordinator was to prepare a manual (NRHP 1994) with a standard bioassessment protocol for use in the program. This was developed with assistance from a technical advisory group and utilises rapid biological assessment (RBA). RBA has the principal benefit of reduced cost (through less time) than traditional, more rigorous quantitative assessment. The main considerations in developing the protocols were:
- habitats to be sampled
- choosing the reference (least impacted) sites
- number and density of reference sites
- sampling areas, intensity and frequency
- sampling devices, mesh sizes
- proportion of sample examined
- live pick versus laboratory analysis
- taxonomic level
- quality control and assurance
- reference site classification
- discriminant analysis
- model development and testing
- model prediction and outputs
- final model evaluation and use.
Details of each protocol are given in the bioassessment manual and are being actively refined. Their adoption and careful adherence are essential to the quality and consistency of the RIVPACS models developed. This aspect has been emphasised in the program through internal and external QA/QC programs.
RIVPACS has been successfully applied to the temperate UK but its application to Australian rivers poses a number of specific issues relating to the scale of our continent, range of environments and greater variability in flow regime. Some of these issues are briefly outlined below.
In Australia, with its extensive land clearance, principally for agriculture, it is not always possible to identify 'pristine' reference sites, particularly for the lowland sections of rivers. Development of RIVPACS in these circumstances requires using the concept of 'least disturbed site selection', that is sites with disturbances judged to be substantially less than the more intense impacts of management interest. The impact on the quality of assessments imposed by this limitation is still to be determined.
The successful construction of RIVPACS (ie with a good predictive power with low error) requires an adequate number and density of reference sites. The MRHI currently includes over 1400 reference sites across Australia. However, the breadth of coverage desired by some state agencies will at this stage limit the power of the first ('RIVPCAS I') models. The potential combination of sets of sites across state/territory boundaries depends on the desire of states/territories to develop and maintain their own RIVPACS models or to collaborate on joint model development. Recognition of the need to develop regional (within or across state/territory boundaries) model development is implicit in the current program.
Australian streams are characterised by high flow variability at a range of time scales with most inland streams being ephemeral. In the large semi-arid/arid region, the streams become a series of pools which contract or even dry out during dry periods. The ability to meaningfully sample ephemeral rivers and develop practical models is, at this stage, highly uncertain.
The seasonal and inter-annual variability of macroinvertebrate communities is largely unknown in Australia and requires careful evaluation of long-term data sets. A lack of stability of these communities will have implications for the sampling requirements and ultimately for the power of the models. Specific R&D is currently being conducted to examine this question.
The MRHI is supporting R&D on a number of alternative and novel methods of river health assessment, some of which will utilise RIVPACS principles and others complement RIVPACS. A brief outline of these approaches is given in the following.
Fish community structure can provide potentially powerful tools for assessing aquatic environmental health. Their key attributes in this task are:
- sensitivity to most forms of human disturbance;
- integration of ecosystem processes and impacts due to position at or near the apex of the food chain;
- ease of identification;
- longevity, allowing the assessment over large temporal scales;
- life-history, population and community level information available;
- acute and chronic impacts detectable;
- seasonally stable populations, sensitive in recruitment to flow events;
- particularly effective for macro-environment disturbances;
- present in small, large and polluted rivers;
- biological integrity of rivers rapidly evaluated; and
- results easily interpreted by community.
In the United States it has been demonstrated that fish can provide a valuable index of river health provided that there is a good database on the species composition and trophic structure in representative basins against which survey data can be compared. The principIes of RIVPACS can be applied to fish and this is being studied at present in the UK (Sweeting pers. comm.) and at Griffith University .The latter project, funded under the NRHP, is assessing the feasibility of developing a River Fish Prediction And Classification Scheme (RIFPACS) in Australia. The first stage of the project is to assess the feasibility of developing predictive models relating fish community composition to river habitat and water quality characteristics.
Diatoms possess a number of attributes suitable for river quality assessment:
- wide, cosmopolitan and abundant distribution;
- well established taxonomy;
- very sensitive to changes in water chemistry with many taxa having well defined ecological optima and tolerances;
- rapid response time reflecting rapid changes in water quality;
- not highly habitat-dependent; and
- easily sampled and preserved.
In the NRHP two projects are being funded to develop a 'Diatom Prediction and Classification System' (DIPACS) based on similar principles to RIVPACS. Effects of sewage disposal, sediment, salinity and nutrient pollution are being assessed.
A great variety of phytoplankton methods have been proposed for monitoring rivers. Some of the advantages of phytoplankton are:
- an important component of the ecosystem in large rivers;
- present before and after pollution;
- directly reflects nutrient pollution better than fauna; and
- different to animals in sensitivity to toxic materials, hence enhancing range of bioassays.
The wide range of methods available and the differing extents to which they can be applied without further development means that it is essential to select methods with care.
In the NRHP, a phytoplankton bioassessment protocol is being developed for Australian rivers to help improve the effectiveness and consistency of agency monitoring programs.
The protocol will include benefits and objectives of phytoplankton assessment and establish a common procedure for sampling, preservation, transport, concentration, identification, counting and data recording.
The determination of biomass, as well as methods of analysis and reporting are also being addressed.
Recent advances in aquatic microbial ecology are resulting in the development of a range of new methods, many based on molecular biology techniques, that may lead to another approach to assessing river health.
The advantages that microorganisms have over other groups are:
- they are present in very large numbers;
- they grow very rapidly and respond quickly to ecosystem changes;
- they can be used as direct indicators of sewage and livestock pollution;
- they can indicate stress by organic chemicals, heavy metals and heat; and
- they are the most diverse biological group and are appropriate as biodiversity indicators of pollution.
The NRHP recognises the potential use of microorganisms in river health assessment but believes a considerably improved understanding of key processes, particularly in unimpacted systems, is required before practical, reliable methods can be developed. A review (Hart et al. in press) of microbial indicators of river health has been commissioned to provide recommendations on priority research in this area.
In Australia, scientific understanding of the ecology of aquatic macrophytes in rivers has not progressed as well as for the other groups, resulting in reservations about their use as river health indicators.
The NRHP has commissioned a project to resolve some of these concerns, specifically interpretation of species absences, role of epiphytes, applicability of the community concept, species presence/ abundance variations at different time-scales and species response to water and sediment quality.
Assessing river health through community metabolism measurement is seen to have two key advantages:
- a more direct and holistic 'process-oriented' measure of river health; and
- an early warning of environmental stress (changes in rates of metabolism may occur before compositional changes in the aquatic community).
The NRHP has funded research to develop a standardised protocol for routine bioassessment in a range of habitats. The methodology involves measurement of changes of dissolved oxygen in perspex chambers in situ to determine metabolic rates of both production (P) and respiration (R) and hence P/R ratios from a range of reference and impact sites.
The future of the National River Health Program is dependent on Cornrnonwealth funding beyond 1995-96. The program described in this section is based on adequate funding for an additional four years.
The principal aim is to conduct Australia's first national river health survey in 1998-99 as a key input to state and national 'State of the Environment' reporting.
The benefits of this survey will be a nationally consistent and scientifically based reporting to the community on the ecological state of the nation's rivers.
The survey will principally rely on use of RIVPACS-Australia but supplementary information will be provided by limited application of RIFPACS, DIPACS and other promising approaches which will be developed further in the future. The national river health survey information will be presented in an easily understood format for community consideration. The second principal aim is to develop a tool kit of reliable bioassessment methods with sound national protocols and guidelines for their most appropriate uses.
Clearly some of these methods (eg microbial) are still in the research domain and will require ongoing investigation of their feasibility and utility. However, by the end of the second funding phase, the more promising tools will be available for use by the water industry.
Some of the subsidiary, but equally important aims are to:
- have predictive tools like RIVPACS and DIPACS used regularly to assess local impacts and pollution incidents;
- enable interpretations of the bioassessments of impacted sites in terms of likely causes or sources of river stress;
- produce a river classification system derived from sample and attribute data to assist riverine floodplain and catchment management;
- identify rivers, river reaches and sites of high conservation value; and
- integrate RIVPACS with the Waterwatch program to provide river, catchment and land care groups with a scientific tool for managing rivers locally.
CEPA (1995). Water Quality Monitoring in Australia. Report prepared for the Commonwealth Environmental Protection Agency by Aquatech Pty Ltd, Feb 1995, 278 pp.
Harris, J H (1995). 'The use of fish in ecological assessments'. Aust.J. &oL 20, 65-80.
Hart, B T , Ross, ] and Veal, D (in press). Microbial Indicators of River Health. LWR-RDC Occasional Paper Series.
Norris, R H and Norris, K R (1995). 'The Need for Biological Assessment of Water Quality: Australian Perspective'. Aust. J. &oL 20, 1-6.
NRHP (1994). River Bioassessment Manual: Version 7. Available from LWRRDC, Canberra.
NRHP (1997). National River Health Program brochure, LWRRDC.
Wright J F (1995). 'Development and Use of a System for Predicting the Macroinvertebrate Fauna in Flowing Waters'. Aust.J. Ecol 20, 181-197.
Dr Nick Schofield is Program Manager - Water Resources, for the Land and Water Resources Research and Development Corporation, a position he has held for three years. Originally gaining a PhD in astrophysics, Nick now has nearly 20 years experience in water resources, undertaking research in catchment hydrology and environmental impacts of mining, forestry and agriculture. He currently manages six national water programs and over 150 projects for LWRRDC.
Dr Peter Davies is a researcher and consultant in aquatic environmental issues. Originally trained in chemistry and ecotoxicology, he was subsequently involved in aquatic faunal and recreational fishery management and aquatic environmental research for 12 years. Based in Tasmania, he has coordinated the National River Health Program for LWRRDC and DEST since late 1993.
* Land and Water Resources R&D Corporation, GPO Box 2182, CANBERRA 2601
# Freshwater Systems, 82 Waimea Avenue, Sandy Bay, Tasmania 7005