Multi-indicator assessment of water environment in government environmental auditing

Available online at www.sciencedirect.com。JOURNALOFScienceDirectSCIENCESJESISN10202972OLEJoumal of Eovironmental Sciences 19(2007) 494 s01www.jcsc.ac.cnMulti-indicator assessment of water environment in governmentenvironmental auditingHE Gui -zhen12, LU Yong-long'", MA Hual-2, WANG Xiao-longl-21. Research Centre for Eco-Environmental Sciences, Chinese Academry of Sciences, Beijing 100085, China. Email: heguizh@yahoo.com.cn2. Graduate University of ihe Chinese Academy of Sciences, Beijing 100039, ChinaReceived 20 August 2006; accepted 24 November 2006AbstractThis study focused on a multi-indicator assessment methodology for govemmental environmental auditing of water protectionprograms. The environmental status of Wuli Lake in China was asesset using the global indicators (rier-saus-response) developedby the Commission on Sustainable Development, and four additional indicators proposed by the author: water quality, pollution load,aquatic ecosystem status, and lake scdiment deposition. Various hydrological, chemical, biological and environmental parameters wereused to estimate the values of the indicators for assessment of environmental status of the lake based on time series data sets fortwenty years. The indicators proposed can be customized to meeting the needs for particular assessment of water protection programs.This method can be used to evaluate the performance of national environmental protection programs and provide technical support forenvironmental auditors.Key words: environmental auditing; environmental indicators; pollution load; lake ecosystem; state assmentIntroductionProtection Agency has proposed the water quality cri-teria (USEPA, 1986) and minimum streamflow criteriaChina has many freshwater lakes, which are important(Tennant, 1976; US Fish and Wildlife Service, 1980) forfor the sustainable development of local areas. The lakesasessing ecosystem status. The Grand Canyon Monitoringhave various functions including storaging flood water,and Research Center (GCMRC) of America monitoredsupplying drinking water, irigation, fish farming andphysical, chemical, and biological parameters to evaluaterecreation. Since the 1980s, population pressures bavethe. status of environmental quality in lake Powell onincreased and the agricultural and industrial productionthe. Grand Canyon River since 1965 (GCMRC, 1999).around the lakes has intensified (Yang et al, 2003). TheseBain et al. (2000) reviewed the assessment and evaluationresulted in a rapid increase of nutrient input, which causedmethods for aquatic ecosystem protection and restoration.major ecological deterioration in the lakes (Qin and Luo,These methods include the EPT index (Bode and Novak,2004; SEPA, 2004). In order to control the negative1995; Novak and Bode, 1992), the index of biotic integritychanges of lake water, some policies, plans and programs(Kar, 1991; Karr and Dudley, 1981), the watersbed habitatwere implemented by the central and local govermmentsevaluation and biotic integrity protocol (Goforth, 1999)(SEPA website). The performance of different policies,and thc integrated river aquifer simulation model (Loucks,plans and programs is an increasing consideration of the1995; Loucks et al, 1996). It should be emphasizedgovermment and the public. Government environmentalthat most of the above mentioned indicators focused onauditing is an important tool for supervising, certifyingstate evaluation and quality description. There were fewand evaluating the performance of environmental policies,connections with governmental policies and programs. Theplans and programs (Bemard and Landis, 1997; INTOSAI,Commission on Sustainable Development (CSD) proposed2001; Wang et al, 2006). However, performance eval-the Driving Force-State Response (DSR) framework ofuation is impossible without the information from pastindicators for the evaluation of many issues pertaining toand present monitoring, as well as science-based watersustainable development (Program, 1995). DSR providedresources decision-making (Jones et al..2001).a link between policy and quality, yet it mainly consideredVarious indicators can be used for asssment of rivermacro aspects and was dificult to relate one state with spe-and lake environment quality. The US Environmental中国煤化工:al auditing paid moreattenC policy evaluation. AnProject supported by the International Project between The NetherlandsimpcMHcNMHGhethemicrodatawithRoyal Academy of Arts and Sciences and Chinese Academy of Sciencesmacro decisions. There is an urgent need for integrated(No. 04CDP014) and the National Natural Science Foundation of Chinaindicators that can help to screen processes in different(No. 40471130). *Corresponding author. E-mail: yllu@cashq.ac.cn.No.4Multi-indicator asessment of water eavironmeat in goveroneat environmental auditing495areas at the local, national and regional level (OECD,ysis using the indicators proposed by the CSD and other1997).indicators can be made to indicate the quality and supplyThe main aim of this study was to give assessment of freshwater resources. The framework of indicators isindicators for lake water in environmental auditing byshown in Fig.2.using those put forward by Kondratyev et al. (2002).In addition to the indicators proposed by the CSD, new| Audit object (Wuli Lake)indicators were proposed, including extemnal loads, waterquality parameters, status of the aquatic ecosystem, andsediment. Then these indicators were applied to Wuli I ake,CSDExterpalWaterBiologicalBottomJiangsu Province, China. The environmental state of Wuliindicators| .loadquality| indicatorssedimentindicators indicatorsindicatorsLake with its catchment and connected rivers, and thechanges in the last two decades were evaluated using theseenvironmental indicators. These indicators can be used by; DrivingState Responsedecision-makers and auditors for auditing the effectivenessforceindicator indicalorindicatorof environmental policies, plans and programs.1 Study area, indicators framework and dataAssessment resultssourcesFig. 2 Franework of assmnent indicators.1.1 Study areaWuli Lake (Fig.1) is a part of the hird biggest freshwater1.3 Data types and sourceslake in China- Taibu Lake. The importance of the lakeAs environmental auditing is a check and verificationaquatic system is recognized by government oficials andprocess, the audit data and information were collectedthe public for sustainable development of Wuxi City,from the audited organization and the third party. WithJiangsu Province. The average depth is 1.8 m. Its waterregard to the governmental audits, the audit data shouldsurface area is 8.6 km2, and its volume is 8.4x106 m3. Thebe authoritative and objective. Data was obtained throughdrainage area is over 50 kmn2. It is connected to the Liangxidocument analysis, literature review, and face -to-face in-River, Mali Gang, Caowang Jing and others. The averageterview. The major data sources are the environmentalannual rainfall is 1112 mm, and average annual runoff isstatistical database of the Environmental Monitoring Cen-4.85x106 m3 (SIDRI, 2002).ter of Environmental Protection Burcau of Wuxi City1.2 Indicator framework(WXEPB), the Wuxi City Statistical Yearbook, the AnnualTo evaluate water quality based on the govermentalEnvironmental Quality Report of Wuxi City, and otherpolicies, plans and programs were implemented, an anal-govemmental documents. The bydrochemical data wereobtained from the sampling stations located in Wuli Lakc.2 Case study resultsJiangsu NntoeLegend2.1 Evaluation of the state of water resources usingWuli LskWuliLakeindicators proposed by CSDThere are three types of indicators proposed by the CSD,Sbanghaiincluding driving force indicators, state indicators, andresponse indicators.ZhejiangThe driving force indicators are IDI, ID2 and ID3. TheHangrbou Baystate indicators include IS, IS2 and IS3. The response in-Hnghoudicators present here are IR;, IR2, IR3, and dimensionlessindicators (indices) IR/IR1, IR3/IR1, IR3/IR2.The values of driving force indicators such as ID1 andFig. 1 Wuli Lake map.ID2 are presented in Table 1. As the study area has largeTable 1 Driving force indicators (ID) of water use in Wul LakeIndicator198519901995199619971998199920002001200220032004AR.9.85.24.6.6.2.L4.94.74.8DI.3.21.41.中国煤化工1.2D216.210.510.99.2.:3.1D，35753126222219MYHCNMHG68AR: annua! rumoff (x10* m); ID: the anowal withdrawal of ground water as a percentage of available water (9%); ID2: the annual withdrawals of surfacewater as a percentage of the surface water resources (%); ID3: domestic consumption of water per capita (L/(person-d)- Resources: Wuxi City StatisticalYearbook.96HE Gui-zhen et alVol. 19resources of surface water, the problem of supplying the(Wang et al, 2006). As a consequence, the water qualitypopulation with drinking water can be solved by usingof the lake was improved to some extent (Chen, 1999).surface water. However, this is not practicable for WuxiAs shown in Table 3, the treatment rate of wastewaterCity due to the critical water pollution. Therefore, more(IR2/IRi) was increasing while the non-treatment rate oftreatment measures must be considered as a promisingwastewater (IR3/IR1) decreased from 1985 to 2004. Thesolution for long-term water supply programs. At present tendency indicatcs an improved efectiveness of the sewagemore attention must be paid to surface water protection andtreatment in the study area.its rational use.The values of the state indicators such as ISI, IS2, and2.2 External load on Wuli Lake and water body of itsdrainage basinIS3 are given in Table 2 (China, GB5749-85; GB3838-2002).The basic components of the extemal load are pointTaking into account the average values of bacteriologi-source and non-point source pollutants. The extemnal loadcal indicators, the surface water quality of Wuli Lake and on a water body is a constant factor to form the chemicalits catchment basin is of class II and its conected nivercomposition of the water and bottom sediment. The waterquality is class II. Sometimes the values of the coli-indexquality and ecological state of the aquatic system areincreased to a dangerous level. High concentrations of governed to a great extent by the level of extemal loadfaecalcoliform rflect the deterioration of epidemiological(Vollenweider, 1968). Changes in value of external loadquality in the polluted water area and pose a serious hazardmay be used as a basis for the assessment of the efficiencyto human health.of water protection measure."he surface water is characterized by an increasedThe following load indicators have been estimated for acontent of organic substances. BODs values beyond thelake drainage basin: IL, IL2 and IL3. The external load ofcritical ones (10 mg O2/L) have been observed every year point source and non-point source pollutants io Wuli Lakein this area, lower than tbe class V of the China nationalwas very high (Chen, 1999; Fan, 1996). IL, L2 and ILsstandard water quality (GB3838 -2002). The highest levelare presented in Table 4 because phosphorus is one of theof organic pollution of surface waters was registered in themost important limited factors of water eutrophication inconnected rivers (38.3 mg O2/L).Wuli Lake (Jiao and Li, 2005).The values of response indicators such as IRI, IR2, IR;As shown io Table 4, the values of all three indicatorsand dimensionless indicators (indices) IR2/IR), IR3/IR1,increased at first (1985- 2001) and then decreased (afterIR3/IR2 are presented in Table 3. Obviously, the higher2002). Though the augment of the treatment plants powerthe IRz/IR; and the lower IR3/IRi are, the better the waterwas observed during the last two decades (Table 3), the in-policies, plans and programs.crease in the extermnal load on Wuli Lake could be explainedFrom the beginning of the 1990s, the eighth, ninth andby the rapid development of industrial and agriculturaltenth Five-Year Plan for Taihu Lake pollution control wereactivities. The most important share of extemal load ondeveloped and implemented successively. The IntegratedWuli Lake is municipal and aquaculture wastewater inflowPollution Control Project for Wuli Lake was carried out which accounts for 70%- -80% of the total. The reductionfrom 2002 to 2004, and some 40 domestic wastewatertrend since 2002 can be regarded as a sign of effectivenesstreatment plants were built or expanded by the end of 2005of the treatment program. The maximal decrease wasobserved in 2004.Table 2 State indicators (IS) of water qualityThe dynamics of phosphorus load on Wuli Lake areshown in Fig.3. From 1985 to 2001, the phosphorus inflowRegionISuIS2IS3m (100000I-V(3.3- 9.5)to Wuli Lake frorm the catchment gradually increased,and there were some years when phosphorus load onConnected rivers692.0(<2000)IV-V(4.8- 12.0)Catchment basin4.(<100001-V (2.8-10.1)the lake was extremely high. The reduction of pollutantsIS: surface water reserves (x10* m2); IS2: class of water quality byload after 2002 was mostly the result of efficient waterpollution treatment. Decrease of load on drainage basincells per liter); IS3: class of water quality by biochemical oxygen demandleads to a decrease of load on Wuli Lake. The loads of the(BODs mg O/L) in water body. Rcsources: Environmental Monitoringother chemicals such as nitrogen and phosphorous showedCenter of Wuxi City EPB.similar temporal dynamics.Table 3 Response indicators (IR) of waste water treatmentIndicator198519901995199619971998199920002001200220032004213464574684895268484231585361152IR22441i374851372332401781572IR378899810292128161551065318IRz/IR;0.110.10.120.140.150.160.200.270.290.310.420.47IR3/IR:0.240.20.190.210.17中国煤化工018Rg/R:2.51.10.3IR: the (otal discharge of waste water (x104 m/); IR2: partly treated wastewate|YHC N M H Gwater (x104 m2a; R/IR;:the treatment rate of wastcwater, IR3/R|: the non-treatmcnt rate of wastewater, Rs/R2: the proportion of non-reated wastewater to treated waters.Resources: Envionmental Monitoring Center of Wuxi City EPB; Wuxi City Statistical Yearbook.No.4Multi- indicator asessment of water environment in govemment environmental auditing497Table 4 Indicators ot TP load (L) on Wui Lake drainage basinIndicator198519901995199619971998199200020012002200320041138.647.462.667.072.773.665.777.556.646.558475916561376170616351506 160151331Li0.0550.0480.0600.0700.0510.0660.0610.0580.0590.0400.0260.014IL1: TP load of basin area (kg/km2); IL2: TP load of surface water (x10-6 kg/m3 ); ILs: TP load per capita (kg/person). Resources: Wuxi City EPB;Wuxi City Statistical Yearbook.2.3 Water quality indicatorsorganic pollutants, nitrogen and phosphorus (Fan et al,The assessment of water quality can be carried out by1992; Fan, 1996; Gu and Lu, 2004; SIDRI, 2002; Yang andcomparing the observed concentration of pollutants withSun, 2001). Although P valuc has tended to decrease sincethe standard concentration (S) as well as by using the2002, long lasting, high concentration pollutants make theintegrated index of water pollution (Ma, 1997; SEPA,water purification process rather slow.Since eutrophication is the key problem in the study2002).area, the cutrophication index was calculated for the estab-lishment of water management plans and assessment of thep=≥=之( 1 ) effectiveness of implemented programs (Jin, 1990, 2001;n台Si n 台Jin et al, 1990; Jin and Tu, 1990; Fan and Chen, 1998; .Jiao and Li, 2005). Assessment of Wuli Lake trophic levelwhere, P is integrated index of water pollution (below itbased on COD, TP, TN, Chl-a and transparency value (SD)is named P value), Ci is the mean annual concentration ofshows that the continuous increase of cutrophication hasa pllutant, and n is the number of pllutanat used for the gradually lead Wuli Lake to a severe eutrophic lake in thecalculation, i=1, 2, ...... P:=Ci;/Si, it is a index of waterlast twenty years, and at present Wuli I ake is in a mediumpollution for i pollutant.eutrophic state due to integrated treatment (Fig.4).In order to calculate the integrated index of waterpollution (P value), five variables were used, including2.4 Biological indicators of lake ecosystemchemical oxygen demand (COD), total phosphorus (TP),The protection of water ecosystems is an essential parttotal nitrogen (TN), chlorophyll-a (Chl-a) and volatileof the planning and management process. The evaluationhydroxybenzene. An increased tendency of P value can beof the state of an ecosystem must consider changes inscen during the last two decades in Fig.4. This fact testifesmajor biotic components and in modes of their interactionthat the problem of pollutio, along with eutrophication,(Bain and Loucks, 1999; Harig and Bain, 1998). Asbecame very serious. As a result of greatly increasedcriteria for the indication of the impact of human activitiesinput of organic pollutants and nutrients, the saprobityon the ecosystem of a lake, the following main bioticand toxicity of Wuli Lake water have also increased.parameters can be recommended for consideration: the pri-According to sanitary-chemical analysis data, water inmary production and decomposition rate of organic matter,different parts of the lake is contaminated differently bythe Shannon-Wiener index of species diversity of floraand fauna, number of dominants and population densities72of different taxonomic groups in planktonic and benthicP infhow-1communities, and indices of molecular ecotoxicology.Recently, a new integrated index (IP) for water quality0.15 Fevaluation based on structural characteristics of zooben-thos was proposed by Balushkina (1997) based on four0.05 iwell known indices.Long-term investigation of Wuli Lake since 1951 has01950 1960 1985 19199999 197 1998 199 2000 2001 202200 2000shown that the concentrations of phosphorus and nitrogenin the water were the main factors that determined primaryFig. 3 Concentration and riverine inflow of total phosphorus in Wuliproduction, species composition of phytoplankton and,Lake.ultimately, the trophic status of Wuli Lake (Fan, 1996;Nanjing Intitute of Geography, 1965, 1982; Zhu, 1959).18The species composition of hydrophyte in Wuli Lake]7has notably changed since the 1950s. In 1951, aquatic76-5macrophyte covered the entire water surface of Wuli Lake,40乞and the dominant plants were reed and water chestnut.na nf the 1980, macrophyte area hast1dec中国煤化In increased, especially1985 1999 1995 1996 1997 1991999 200200 2002 203 2000Oscsp. (algae with highYearCNM.HG 1983; sIDRI, 202Fig. 4 Integrated index of water pollution (P value) and eutrophicationThe excessive discharge of phosphorus and nitrogen couldindex (NI),cause algae bloom. Tbe biomass of phytoplankton in Wuli498I正Cui-zhen et al.Vol. 19lake bhas been observed (Fig.5), indicating the algae bloomDue to the dificlty and complexity of sampling andincidents in 1990, 1994 and 1997.monitoring the sediment, the following parameters can beconsidered: the concentration of heavy metals such as Cu,140 [Zn, Cd, Pb, Ni, As, Hg, Cr, and nutients including organic20matter, TP, TN; the horizontal and vertical distributionof pollutants in sediment; exchange across the sediment-80water interface carried out by calculation of the value of50 Lphosphorus fux from the sediment to the overlying waterand dimensionless indicators such as: (1) Lan/L,' where Lan:0 tis the intemal nutrient load on the lake (g/(m2-a)) and Lln.n.1...Iis the extemal nutrient load on the lake (g/(m2a)); (2)1951 19801987 1988199019931997 2000 2003S/L. where s represents nutrient sedimentation on the lakebottom (g/(m2a)); (3) f, relative input of benthic notrientFig. 5 Biomass of phytoplankton in Wuli Lake,fux into the total nutrient storage in the water mass.Because of the small volume of Wuli Lake, human ac-Zooplankton is mainly considered as an indicator oftivities afect the whole area. The pollution level of heavysaprobity or trophic state of a water body. Moreover,metals was lower than the Environmental Quality Standardzooplankton indices based on taxonomic composition, sizefor Soils (GB15618-1995), when calculated with the Igodistribution and trophic level may be of high informativemethod (Shen et al, 2004). However, concentrations ofpotential (Andronikova, 1996). Zooplankton showed veryorganic matter, TN andTP were typically 2- -5 times higherhigh variation of the average numbers and biomass valuesin sediments of the polluted area than in sediments of thesince the 1950s (Fan, 1996; Fan et al, 1992; Nanjingunpolluted area in Taihu Lake (Fan et al, 1998a; Luo andInstitute of Geography, 1965, 1982; Zhu, 1959). As shownShi, 2003).in Table 5, zooplankton communities have demonstratedEutrophication causes an increase in concentrationsdistinct reduction.of nutrients and intensity of mass exchange across thesediment-water interface, enbancing a role of bottom sed-Table 5 Varation of zooplankton speces in Wuli lakeiments as a intemnal source of nutrients for the lake waterCommunity1951 19811984 19871996 2002mass. " can be seen in Fig.6 that nutrient (P and N)concentrations in sediments of Wuli Lake had increasedProtozoa0313Rotifera22916since 1960, and the content of N and P rose to its peakCladocera818910value in the 1990s (Fan et al, 1998a; SIDRI, 2002; ShenCopepoda71728et al, 2004; Yuan et al, 2002; Zhang and Wu, 2002).Here we explain the indicators of the lake's stateResources: SIDRI, 2002.by the characteristics of "sediment- water" exchange forphosphorus. Studies of phosphorus exchange across theStructural and numerical data on macrozoobenthossediment-water interface showed that the value of releascprovide good indication of changes in the ecosystem.rates of phosphorus from sediments to overlying waterCommunities of benthic invertebrates in Wuli Lake havevaried from 2.75- 3.14 pg/(g:d) (Yin et al, 1994; Wang etbeen changed since the 1970s. Species diversity withinal, 1996). The amount of phosphorus fux from sedimentsaquatic communities is closely related to the trophic statc to overlying water was from0.584 -2.05 mg/(m2.d) in 1996of the water. Earlier, Gilyarov (1969) and Alimov (1990)(Fan e1 al, 1998b). The increase of intermal nutrient releasedemonstrated an inverse relationship between the valuesmeans the decrease of nutrients sedimentation on the lakeof the species diversity and biomass of diferent groups of bottom. The S/L value will be smaller when the externalplanktonic and benthic invertebrates in lakes.load entered into the lake is fixed.However, to draw adequate conclusions from the as-Ibe values of indicators addressed the developmentsessment of the ecological situation on the basis of of eutropbication in Wuli Lake in the early 2000s werecomposition, size and diversity of planktonic bacteria,algae and invertcbrates, it must be considered that all these0.301 0.20groups of living organisms characterize different aspects of0.25-T-INecosystem state and water pollution, and the rate of their- 0.16_0.20response to pollution is also diferent.70.12二0.152.5 Bottom sediment indicators0.080.1Bottom sediment represents the result of the accumula-0.05 t0.04tion processes of extemal chemical substances over a long中国煤化工time (Chen and Fan, 1998). The sediment should therefore199 2001 2003be considered as a potential source of secondary pollutionYHCNMH Gand as one of the indicators of the lake ecosystemn's healthFig. 6Changes of nitrogen and phosphorus for btom sediments in Wuli(Martynova, 1988).Lake.No.4Multi-indicator assment of water eovironment in govermment enviromental auditing49as follows: Lnm/L=0.26; S/L=0.38;f=0.43 (Environmentalalso the intermal pollution source of eutrophication in WuliMonitoring Center of Wuxi City EPB; SIDRI, 2002). ItLake. Parameters of bottom sediment indicated a sign ofwas found that when Lin/L>0.1, the role of bottom sedi-improvement recently.ments was significant in lake eutrophication (Martynova,1988). As the eutrophication developed, the value of the4 ConclusionsS/L ratio decreased. In lakes where the f value exceeded0.25- 0.30, phosphorus input from the sediments becameAn integrated evaluation framework has been proposedsignificant for the eutrophication process.herc by a combination of macro D-S-R indicators and fourAll indicators used during environmental asssment aretypes of new indicators. This will be belpful for auditorsshown in appendix.to define auditing criteria, collect data, analyze and assessdata and obtain specific auditing conclusions.3 DiscussionFor the Supreme Audit Institution, water auditing is anew field. Several points should be taken into account ifIn principle, either single-criterion or multi-criteriathe multi-indicator framework is applied in more auditingauditing methodology can be adopted to perform a struc-cases which are as follows.tured multidimensional quantitative analysis, noting thatGathering gcneral data from various sources: watertheir goals and usefulness depends on the context. Amanagement dealt with many public sectors in China.single-criterion auditing approach is constructed mainlyEach sector had its own monitoring data. Auditors hadwith monetary valuation while the multi criteria approachgreat difficulty in collecting appropriate data to analyzeextends this to incluode explicit environmental factors. and evaluate consistently. Even though the same auditingConscquently there is a move towards a multi-criteriacriteria and indicators are used, the auditing suggestionsauditing approach in public and govenment sectors en-might be diferent if data sources are diverse. In thisgaging in environmental protection. In this paper, several regard, the relevant departments sbould develop a uniformindependent quantitative and qualitative evaluation criteriadatabase at the beginning of decision making.were constructed. However, a basic conviction underlyingFlexibility of multi- indicator methodology: differentall approaches is that the use of several criteria is better for environmental issues exist in various rivers and lakes.robust environmental auditing while facing multidimen-The muli indicator framework is not a“dead" method.sional and ill- defned problems.It should be adjusted to apply in different conditions.There are many evaluation methods for water environ-For example, if the multi-indicator framework is used toment, including driving force, state and response D-S-Revaluate a river environment, the sediment indicators mayindicators proposed by the CSD which were applied innot be necessary.Wuli Lake case. Results indicated that relationships existedIntegration with other indicators: waterpollution andamong the three kinds of indicators. Values of drivingmanagement is a complex issue. Effectiveness of waterforce indicators showed an increasing trend during the lastcontrol project is influenced by social, economic andtwo decades (Table 1). The water environment status ofother factors. The multi-indicator methodology should beWuli Lake gradually deteriorated which was indicated bycombined with social and economic evaluation indicatorsthe concentration of faecal coliforms and BOD (Table 2).in order to put forward objective and reliable auditingThe govermments have intensified their pollution control,recommendations.environmental monitoring and management for Wuli LakeCooperation with multi disciplinary experts: auditors(Table 3). Conscqucntly, the wastewater treatment rateare generally educated with accounting and econom-increased. The D-S-R model shows water environmentic backgrounds. They would face special barriers inchanges and pollution control of Wuli Lake. The modelthe process of conducting water environmental auditing.paid more attention to the macro trend of the study object,Cooperation is needed between environmental auditors,but it could not provide specific auditing criteria and reli-environmental scientists and consultants for identifyingable auditing suggestions for in-depth project evaluation.auditing criteria and indicators, collecting auditing data,In order to f1l the gap, four types of indicators of extemnalanalyzing project effectiveness and obtaining auditing con-pollution load, water quality, aquatic ecosystem and lakeclusions.sediment were proposed in this paper. Various hydrolog-Acknowledgements: The authors would like to thankical, chemical, biological and environmental parametersthe National Audit Ofice of China (CNAO) and Chengduwere used to estimate the values of diferent indicators forResident Oflice of CNAO for their support. We are gratefulassessment of environmental status of the lake based onto anonymous reviewers for their comments.time series data sets for twenty years. Resuls showed thatamount of extermal pollution load (TP) generally increasedAppendixbefore 2001, and after that it became small (Table 4,Fig.3). Correspondingly, the water quality of Wuli LakeType中国煤化工-was improved (Fig.4). The aquatic ecosystem signifiedCSD irMYHCNMHGby phytoplankton and zooplankton was still in unbalanceDriving forceD1Anual withdrawal of ground watersituation (Table 5, Fig.5). Lake sediment was the resultindicatorsas a percentage of available water (%)of aggradation of the extcrnal pollution load, and it wasNo. 4Multi-indicator assessment of water environment in govemment environmental auditing501tors(J]. Ecol Indic, 2: 79 92.Shen Y L, He P J, Shao L M, 2004. Characeristics of contaminat-Loucks D P, 1995. Developing and implementing decision sup-ed sediments in Wuli Lake of Tai Lake[J]. Resour Environport systems[J. 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