parameter not fully established.

**Table 3.** National Lake Water Quality Criteria and [C2]Standards 2015 [30].

Biochemical and microbiological parameters suggested in the standard include BOD, COD, total and faecal coliforms, *E. coli*, enterococci, cyanobacteria and three pathogens, namely *Cryptosporidium* sp., *Leptospira* and *Giardia* sp. [31]. Few researchers have debated the suitability of faecal indicator bacteria such as faecal coliform, enterococci and *E. coli* in tropical freshwater bodies [33, 34]. These studies show that the indicator bacteria can multiply to establish itself in the soil of tropical countries, and are thus inadequate to suggest an indicator of pollution from human and animal faeces [32, 33]. In another study, *Clostridium perfringens* has been suggested as a better indicator for recreational water quality standards in tropical countries due to its inability to multiply in the soil [35]. Despite this variability, enterococci and *E. coli* remain widely used as indicators of faecal coliforms [36]. In order to apply these standards to Malaysian lakes, *E. coli*, enterococci and *Clostridium perfringens* were identified as indicators. Additionally, pathogens such as *Cryptosporidium* sp., *Leptospira* and *Giardia* sp. were included as they can lead to potentially severe disease outbreaks in Malaysia, such as diarrhoea. Waterborne disease associated with *Cryptosporidium parvum* and *Giardia duodenalis* has emerged as an important public health concern in developed and developing countries [37]. The presence of *Giardia* sp*.*, *Cryptosporidium* sp*.* and *leptospira* sp. have been reported in some of the urban lakes suggesting the use of this water body for recreational purpose is a major health concern [38, 39] and requiring monitoring and enforcement of source of pollutants.

Stakeholders recommended monitoring of five heavy metals in lakes, namely arsenic, cadmi‐ um, lead, mercury and nickel, due to their toxicity in human health. Some of these chemicals were frequently detected in many rivers throughout Malaysia [12]. Arsenic was classified as very toxic and widely associated with industrial pollution from the mining industry, dye manufacturers, the glass and ceramics industry, fertilizers and pesticides [40]. High arsenic levels were reported in post‐mining lakes such as Blue Lake, due to its use in the gold mining process. This has led to the barring of the lake for any human activities [41, 42]. Both cadmium and lead are potentially hazardous to most forms of life and are considered to be toxic to aquatic organisms. The main environmental sources of cadmium are discharges from mining, metal smelters and agricultural uses of sludge, pesticides and fertilizers. For lead, the main sources are anthropogenic activities such as runoff associated with lead emissions from gasoline‐ powered motor vehicles, and industrial and municipal wastewater discharges [26, 40]. Mercury is of major concern in the natural aquatic environment due to its extreme toxicity to aquatic organisms, high concentrations of which in water bodies are associated with industrial pollution. Information on many toxicants, in particular pesticides in Malaysian lake water quality were not found in the literature. The threshold limit for many toxicants provided here presents as a starting point for monitoring of the pollutants. Future studies on threshold levels of toxicants in lakes are needed to confirm and validate the criteria.

### *3.3.2. Role of standards and limitation*

**Parameter Unit Category A Category B Category C Category D** Pendimethalin μg/L 20>k 20>k 20>k 20>k Pentachlorophenol μg/L 9>k 9>k 9>k 9>k Permethrin μg/L 20>k 20>k 20>k 20>k Pesticides μg/L nvd nvd nvd nvd Phenol μg/L 5g 5g 5g 5g Polycyclic Aromatic Hydrocarbons μg/L nvd nvd nvd nvd Propanil μg/L 20>k 20 20 20 Selenium mg/L 0.01fj 0.01f 0.01f 0.01f Simazine μg/L 20k 20k 20k 20k Sulphate mg/L 250j 250>j 250>j 250>j t‐DDT μg/L 0.1ai 0.1ai 0.1ai 0.1ai Tetrachloroethene and Trichloroethene μg/L 10gj 10gj 10gj 10gj Total indicative dose μg/L nvd nvd nvd nvd Total organic carbon (TOC) μg/L nvd nvd nvd nvd Toxicants (heavy metal, organics) μg/L # # # # Trichloroacetic acid μg/L 100>k 100>k 100>k 100>k Trichloroaceto nitrile μg/L 1>k 1>k 1>k 1>k Trihalomethanes–Total μg/L 1000>k 1000>k 1000>k 1000>k Tritium μg/L nvd nvd nvd nvd Vinyl chloride μg/L 5>k 5>k 5>k 5>k

Gross‐alpha Bq/L 0.1ai 0.1ai 0.1ai 0.1ai Gross‐Beta Bq/L 1ai 1ai 1ai 1ai Radium‐226 Bq/L <0.1ai <0.1ai <0.1ai <0.1ai Strontium‐90 Bq/L <1ai <1ai <1ai <1ai

NV, not visible; NOO, no obvious odour; NOT, no obvious taste; nd, not detected; nvd, no value determined.

Biochemical and microbiological parameters suggested in the standard include BOD, COD, total and faecal coliforms, *E. coli*, enterococci, cyanobacteria and three pathogens, namely *Cryptosporidium* sp., *Leptospira* and *Giardia* sp. [31]. Few researchers have debated the suitability

*Notes*: Item in light grey—should be measured for categorization.

*Radiological parameters*

306 Water Quality

Health Canada [17].

Ministry of Health, unpublished report.

h Conversion using USEPA ratio (126 *E. coli* = 200 faecal).

**Table 3.** National Lake Water Quality Criteria and [C2]Standards 2015 [30].

ANZECC [6]. d USEPA [24, 25].

g EPA Ireland [40].

 CONAMA [5]. k NDWQS. \*

Perbadanan Putrajaya [13].

maximum not to be exceeded.

parameter not fully established.

a DOE [12]. b

c

e WHO [16].

f

i

j

#

The proposed standards were based on expert judgement and the best available information found in the literature. Part of the role of the NLWQCS is to provide the directional targets for research and management programmes. The standards can be used to guide rehabilitation measures and conservation efforts as well as to develop management measures to address eutrophication issues. The standards are proposed to be non‐binding and to be gradually improved as more information and data are gathered by the stakeholders. As water quality monitoring in lakes in still in infancy, this NLWQCS does not provide a plan for enforcement to enable protection of the uses nor become an established regulatory criterion with legal ramification. However, the criteria can also be used by the respective agencies and stakeholders to assist in monitoring and to classify various lakes under their regulatory or management controls for their fitness for different uses.

In the proposed document, the sampling strategy was not described in detail. Water quality in lakes is known to differ temporally and spatially, both horizontally and vertically depending on lake depth. Seasonal and daily variations associated with irradiance, along with dissimi‐ larity in surface waters' mixing related to weather patterns can induce variations in tempera‐ ture, DO and the transportation of nutrients or pollutants. Thermal and chemical stratification are common features of deeper lakes which affect the water quality being monitored. Variations in water quality are also dependent on the composition of discharges over both short and extended periods. Discharges from housing, commercial buildings and industry can vary within a day, a week or a season. Domestic discharges depend on the homes' occupancy, which is usually higher during the early morning, at midday and in the early evening, while industrial discharges depend on operation hours. Higher home discharges and lower industrial dis‐ charges could happen during weekends and festive seasons. Exceedances of bacterial indicator to health risk were also temporally sporadic and geographically limited with the reduction of pollutant loading not necessarily reducing the health risk [43]. Narrative criteria were pro‐ posed in NLWQCS namely to consider the size and shape of the lake when choosing a sampling location, so that the site selection is representative of the whole lake. The choice of site for routine water monitoring sampling can make a significant difference to the classification of microbial water quality [44], owing to the hydrodynamics and proximity of pollutant sources.

With respect to the criteria for protecting aquatic life in the NLWQCS, many limitations exist due to unavailability of extensive data. The criteria in this are mostly based on chronic and acute effect values in temperate countries which have different species. Most of the water quality criteria were also based on a single pollutant model which mostly targeted single species instead of community response [3]. Some of the criteria for aquatic life protection adopted the same value for the human health protection criterion assuming that the effects to all types of aquatic life, all stages of their life cycle and the whole aquatic community are similar. Further research is much needed on deriving the chronic and acute effects of many pollutants on freshwater local species in order to establish more accurate criteria for protecting the Malaysian aquatic environment.

In these criteria, the sampling methodology aims at testing the ambient condition of the lakes via a minimum of three sets of samples, to be monitored at least twice a year, once in the dry and once in the wet season. The proposed depth is surface measurement, in accordance with standard methods [45]. However, adult chest depth at ∼1.2–1.5 m is the most common sampling depth recommended in the United States and Canadian recreational guidelines, due to strong evidence in the form of the mathematical relationship between indicator organism density and swimmer illness. Intensifying the number of samples and frequency of monitoring may provide a better representation of the lake's overall water quality and trends. A minimum frequency of once per week during the swimming season was recommended by Canadian guidelines [17] and monthly by the UK and a few US states [9, 46, 47], in order to make more informed decisions regarding lake suitability for recreation. As bathing or swimming activities in lakes is not widely practiced in Malaysia, nor is there a specific swimming season, moni‐ toring measures will depend on the authority's management budgets.

In order to determine the extent of violation or compliance levels, this standard proposes the 90th percentile of sampling results to be considered as acceptable for determining any class. Few guidelines or standards such as in the United States propose the use of dual limits, with the first being a maximum limit for the geometric mean concentration over an interval, and the second being a single‐sample maximum or threshold limit set to better evaluate the water quality in both the short‐ and long‐term. The short‐term limit is usually set over a 30‐day interval and aims at addressing immediate water quality issues, while the long‐term limit is set over the duration of the swimming season and aims to address chronic contamination problems. Other standards such as that of the UK advocate the use of percentage compliance levels, mostly of 95% or 90% [46] and some others such as Japan use annual averages [48]. The 90th percentile was taken into account following stakeholder consensus, the values of which consider top end variability in the distribution of water quality and also in order to curb influence of possible small sample sizes. The water quality classification of risk or status was not described in the NLWQCS due to unavailability of reference data.

Financial issues relating to water testing were collectively identified by the stakeholders as major challenges for NLWQCS implementation. Water quality monitoring was usually performed based on the parameters to estimate the water quality and Carlson's trophic state index [49] due to limited funds. Pathogenic parameters such as *Leptospira* and *Giardia* sp. are rarely monitored. Measurements were usually undertaken by the relevant departments when there were reported cases. In this NLWQCS, focus is placed on the main physicochemical, microbial and selected toxicants in order to promote lake monitoring. The main aim is to monitor and control nutrient, microbial and organic pollutants, and improve aesthetic values of existing lakes. The various lists of pesticides and toxicants is encouraged to be monitored if funding is not limited and if testing methods are available at lower detection limits, such as for trace chemicals. The proposed criteria and standard serve as a reference and a starting point in the proper monitoring of lakes and in working towards sustainable management of the water bodies. Future review has been suggested upon the availability of more data from monitoring efforts, and possibly to expand the standard further from water quality‐based management to ecologically based management to protect the whole aquatic system [21]. It is hoped that the criteria will evolve and be adopted as a regulatory monitoring program in the future to enable a better connection to standard compliance and violations.
