NATIONAL MICROBIAL WATER QUALITY MONITORING PRGRAMME

A First Report

On the Identification and Prioritisation of Areas in South Africa with a Potentially High Health Risk Due to Faecally Polluted Surface Water

 

Report No: N /0000/00/RE/Q/4399

Date: August 2000

Project Management: Dr A L Kühn; Ms M du Preez

Report Compiled by: Mr H van Niekerk

Data Collection: Ms C van Ginkel; Ms L Zingitwa; with assistance of the Directorate: Water Services Planning and DWAF Regional Offices

Data Processing: Mr S N Venter; Ms C van Ginkel

Graphic Representation: Dr K Murray; Ms E Vermaak

Definition of a "Potential High Health Risk Area" as Used in the National Microbial Water Quality Monitoring Programme (NMMP)

The term "potential high health risk area" is used in the NMMP to describe
an area that has (at the time that the assessment was done) been exposed to factors that might have contributed to a potential health risk, due to faecal pollution of surface water resources, in that area.

 

 

1. PURPOSE OF THE REPORT

This report gives a description (with results) of the process used for identifying areas within South Africa where faecally polluted surface water poses a potentially high health risk to the community. The purpose of this exercise was to create a prioritised short-list of areas in which to establish a National Microbial Water Quality Monitoring Programme (NMMP).

2. NATIONAL WATER RESOURCE QUALITY MONITORING PROGRAMMES

The Department of Water Affairs and Forestry (DWAF) is, in terms of the National Water Act (Act No. 36 of 1998), responsible for the coordination, organization, control and further development of national water resource quality monitoring programmes. Monitoring, recording, assessing and disseminating information on water resources is critically important for achieving the objectives of the Water Act (Chapter 14 Section 137 of the Act).

A number of national water resource quality monitoring programmes are already in place. The national chemical water quality programme has been operational for many years. A national biomonitoring programme is currently being implemented.

South Africa does not have a central source of information for assessing the potential health risks associated with faecally polluted surface water. To supplement the existing national water resource quality monitoring programmes DWAF commenced in 1994, with the design of a national microbial water quality monitoring programme. Implementation of this programme has become a high priority as South Africa's water resources are coming under increasing threats from faecal contamination. This situation is mainly due to the rapid demographic changes currently taking place that are resulting in numerous dense settlements without appropriate sanitation infrastructure. Poorly maintained waste water treatment works in many parts in the country also add to the problem.

3. OUTLINE OF THE NATIONAL MICROBIAL WATER QUALITY PROGRAMME (NMMP)

3.1 Goal of the programme

The goal of the national microbial water quality monitoring programme is to, on a national scale, provide the information needed to assess and manage the potential health risks to water users related to the faecal pollution of South Africa's water resources.

3.2 Scope of the programme

The initial scope of the programme is limited to providing the management information required to assess and manage the potential health risks related to faecal pollution of South Africa's fresh surface water resources used for potable, recreational and irrigation of edible crops consumed raw.

The full scope will eventually include ground water resources used for potable and recreational purposes as well as irrigation of edible crops consumed raw. Estuaries heavily used for recreational purposes will also be included.

3.3 Objectives of the NMMP

Water resource managers and other role players are responsible for, or involved in maintaining, the quality of South Africa's water resources are seen as the main users of a national perspective on microbial water quality and the potential health risks involved in utilising the water. The information will also be of value to other role players such as researchers in the water field as well as health officials. The specific objectives of the National Microbial Water Quality Monitoring Programme are therefore:

 

4. MICROBIAL WATER QUALITY CHARACTERISTICS

Microbial constituents have a pronounced non-conservative behaviour in water bodies. This means that their concentration can change independently of the amount that was originally added to the water body. Change of their concentration in surface water can result from a number of processes such as growth, decay, settling and chemical reactions. The non-conservative behaviour of microbes makes the operational aspects of a monitoring programme logistically difficult and costly, as samples have to be analysed within 8 to 24 hours after they have been collected.

The implication of the non-conservative behaviour of microbes (both pathogens and indicators of faecal pollution) is that it would be almost impossible, without large investments in resources, to sample at representative locations on a national "grid" to obtain an overall picture of the microbial quality of surface water resources. Cost-minimisation is critical for the sustainable operation of national water quality monitoring programmes. The microbial monitoring programme was thus designed to focus on potential high health risk areas where there would be a high possibility of the water being faecally polluted and where it would pose a major risk to the health of water users in the given area (Institute for Water Quality Studies, 1996).

 

 

5. FACTORS DETERMINING THE POTENTIAL HEALTH RISK OF FAECALLY POLLUTED WATER

The risk of faecal pollution and concern about the impacts of water polluted with faecal matter, that is, its microbial quality, are much higher in some geographic areas than in others because:

The factors determining the potential health risk are summarised diagrammatically in a systems model depicted in Figure 1.

Figure 1. Schematic illustration of problematic land uses, sensitive water uses and impacts of health risk (Murray, 1999)

 

6. IDENTIFICATION OF HIGH HEALTH RISK AREAS

Spacing of monitoring stations evenly, on a geographic basis, throughout the country, would be costly due to the logistics involved and would not supply the information needed to assess the potential health risk to the affected users.

The monitoring programme therefore focuses on potential high health risk areas only, as determined according to the following criteria:

The two main attributes that were used in the process for the identification and prioritisation of potential high health risk areas were specific land uses and water uses (Figure 2).

Land use causing faecal pollution + Water use sensitive to faecal pollution=Potential Health Risk

Figure 2. An illustration of the two main attributes used to prioritize potential high health risk areas.

 

7. PRIORITISATION OF HIGH HEALTH RISK AREAS

To accommodate possible constraints in the availability of financial and human resources, priority rankings were assigned to the identified potential high health risk areas. The prioritisation of potential high health risk areas was done according to a "Simple Multi-Attribute Technique" (SMART) as described by Goodmin and Wright (1991). Figure 3. Illustrates some of the issues that the individual steps in this process address (Murray, 1999).

Figure 3. An illustration of some of the issues addressed by the major steps in the national prioritisation process (Murray, 1999)

 

8. THE PRIORITISATION PROCESS

National prioritization involves the cursory (though quantitative) examination of catchments throughout South Africa. The aim is to identify potential high health risk areas where the microbial water quality is suspected to be severely impacted and where it poses a major potential health risk to water users in the area. The identified areas are thereafter prioritised to facilitate (if necessary) a phased implementation of the monitoring programme.

The prioritisation process that was followed is summarized in Figure 4 and described in the following sections, namely;

8.1 SCREENING for potential high health risk areas.

8.2 RANKING of areas identified in screening process according to health risk.

8.3 SELECTION of high health risk areas.

 

 

 Figure 4. Overall National Prioritisation Process (Murray, 1999)

 

8.1 SCREENING for Potential High Risk Areas

The screening process for potential high health risk areas consisted of mainly two steps, namely the collection of preliminary data and the selection of a short list. Due to the high cost of monitoring only those areas posing a significant potential health risk to water users were considered. Those with no potential or actual microbial problems were excluded.

 

8.1.1 Collection of preliminary data

The following procedure was followed to obtain the information required to facilitate the initial screening of catchments:

 

8.1.2 Selection of short list

The initial screening of all tertiary catchments was performed according to the criteria listed below. Thereafter all quaternary catchments which were part of the selected catchments were again screened according to the same criteria in order to improve on the resolution to a quaternary catchment scale.

The following criteria were used to identify potential high health risk areas during the screening process, namely;

  1. Microbial water quality problems have been experienced in the catchment.
  2. A high incidence of water borne diseases was evident in communities in the catchment.
  3. People in the catchment were using untreated or partially untreated water for domestic use.
  4. There were settlements in the catchments (or upstream of the catchments) that did not have the necessary sanitation infrastructure to ensure effective disposal of human waste.

A short list of potential high health risk areas was selected based on the criteria set out above. The aforementioned catchments are indicated on Map 1. If land uses in one catchment poses a potential high health risk to water uses in another catchment, the relevant catchments were clustered together to form one potential high risk area (see Map 2).




8.2 RANKING of Areas According to Potential Health Risk

The purpose of the second main step was to quantitatively rank areas in the catchments (as identified on Map 1) according to their likely health risk.

8.2.1 Collection of detailed data

The information was obtained from the following sources, namely:

Information on the following sub-attributes was obtained for each settlement within a potential high risk area in the identified catchments to determine land use ratings and water use ratings:

Sub-attributes used to determine water use ratings

  1. The number of individuals without appropriate or reliable water supply infrastructure, that have to rely on untreated surface water.
  2. The number of individuals supplied with surface water from the catchment for drinking after limited treatment.
  3. The maximum number of people per month that have full or partial contact with surface water in the catchment.
  1. The area in hectares with vegetables that are irrigated with surface water from the catchment.

 

Sub-attributes used to determine land use ratings

  1. The number of individuals with no sanitation infrastructure.
  2. The number of individuals with sanitation infrastructure that is inefficient, poorly maintained or inappropriate.
  3. Average population density.
  4. Intensive livestock farming with no waste handling practices in place (small, medium or large).

 

8.2.2 Rating of land use and water use

Weights were assigned to all sub-attributes mentioned in 8.2.1 above. These weights were normalised and then used for the determination of water and land use ratings respectively (Venter, 1998).

 

8.2.2.1 Rational behind relative priorities (weights)

Not all the above land use activities have the same impact on the microbiological quality of surface water and similarly not all water uses are impacted to the same degree by faecally polluted water or the associated potential risk of disease. To ensure that the prioritisation process is as objective as possible a "Simple Multi-Attribute Rating Technique" (SMART) as described by Goodmin and Wright (1991) was used to assign weights to the identified land and water uses.

According to the technique a measurement scale was selected for land and water uses. Thereafter weights were assigned in terms of their relative importance (Venter 1998). These weights are based on the consensus of the technical team that was involved in the monitoring design. Tables 1 and 2 gives an indication of the original and normalised weights that were assigned to the abovementioned sub-attributes.

Table 1. Original and normalised weights for land use information

Land uses

Original weight

Normalised weight

No sanitation infrastructure

100

53

Inefficient sanitation infrastructure

60

43

Intensive farming enterprises

6

3

Percentage surface area covered

2

1

Total

168

100



Table 2. Original and normalised weights for water use information

Water uses

Original weight

Normalised weight

Drinking of untreated water

100

50

Full or partial contact recreation

50

25

Irrigation of crops to be consumed raw

30

15

Drinking limited treatment

20

10

Total

200

100



All the above sub-attributes were then quantified as indicated in tables 3 and 4. As indicated in table 3 an intensive animal farming enterprise was rated as a function of its size.

 

8.2.2.2 Determining of total land and water use ratings

The weighted sub-attributes together with all the relevant information gathered for each settlement in a specific potential high health risk area were used to calculate the water and land use ratings for all the areas on the short list (Map 1) respectively. For each settlement data was collected for all the sub-attributes indicated in Tables 3 and 4. The values for these sub-attributes were summed for all settlements in an area and the final land and water use ratings were determined for each area respectively as shown in tables 3 and 4.

As explained in section 8.2.3 the total land and water use ratings for each potential high health risk area were then used to calculate the overall area rating for each potential high health risk area.

Table 3 Determination of the total land use rating for an area (Murray, 1999)

No

Land Use Attribute (whole area)

Priority Rating

1

The number of individuals, N, with no sanitation infrastructure

(N/100 000) x 100 x 53

2

The number of individuals, N, with sanitation infrastructure that is either inappropriate, or poorly maintained

(N/100 000) x100x43

3

Average population density (people/km2), N, in area

(N/20 000) x100

4

Intensive livestock farming with:

no waste handling practises in place

Small Scale Unit

90

Medium Scale Unit

180

Large Scale Unit

300

all units with appropriate waste handling in place

0

Total Land Use Rating for Area =

Sum



 

Table 4 Determination of the total water use ratings for an area (Murray, 1999).

No.

Water Use Attribute (whole area)

Priority Rating

1

The number of individuals, N, without appropriate or reliable water supply infrastructure that have to rely on untreated surface water for drinking

(N/100 000) X100X50

2

The number of individuals, N, supplied with surface water from the catchment after ...

limited treatment

(N/100 000) x100x10

conventional treatment

0

3

The maximum number of people per month, N, that have full or partial contact with surface water in the area

(N/10 000) x100x10

4

The area in hectares, ha, with vegetables that are irrigated with surface water from the catchment

ha x 15

Total Water Use Rating for Area =

Sum



 

 

8.2.3 Ranking of potential high health risk areas

After all the potential high health risk areas identified in the short list have been assigned land and water use ratings, these ratings were used in the following simple calculation to calculate an Overall Area Rating for each area on the short list. The relative weights of land and water information were determined to be 4:6.

Overall Area Rating = 0.4 x (Total Land Use Rating for Area)+

0.6 x (Total Water Use Rating for Area)

Map 3 indicates the catchments ranked according to their assessment values (overall area rating) as calculated with the above calculation. The potential high health risk areas are shown as different color coded categories. The cut-of values for these categories are as follows:

Colour

priority values

Blue

0 - 10 000

Green

10 001 - 100 000

Yellow

100 001 - 1000 000

Red

1000 001 - 10 000 000

 

8.3 SELECTION of Potential High Health Risk Areas

Using the assessment values (ratings) indicated on Map 3 the relevant catchments were then listed from the area with the highest potential health risk probability to the lowest potential health risk. These results are indicated in Map 4 herein and in the appendix.

 

9. Prioritisation Frequency

This first prioritisation exercise was very comprehensive. Many tens of areas were identified as requiring a monitoring programme (see Map 4). However, due to rapid changes in land and water use patterns, this situation can change and therefore it is proposed that this National Prioritisation Process be repeated 5 yearly or when the need arises e.g. after the next census.

 

 

 

10. DISCUSSION

10.1 Interpretation of Maps

By displaying the information on maps potential high health risk areas can easily be identified by visual inspection. However, the following principles must be borne in mind when interpreting the maps:

10.2 Data Collection

A number of difficulties were encountered in collecting the data. Information for some of the prioritisation criteria (indicated in paragraph 8.2.1.) was not available or could not easily be accessed. Therefore, a number of changes had to be made to the types of data collected and the calculation of priority values.

The following categories of land and water use attributes were affected:

Percentage surface area covered

In the original design it was proposed to obtain data of the actual surface area covered as a measurement for the percentage surface area covered. This information was very difficult to obtain. Information obtained by the manual interpretation of aerial photographs was evaluated as an alternative. However, this would have been an expensive and time consuming process and in the light of the low weighting assigned to it, it was decided to measure the potential for contaminated surface water runoff in terms of population densities instead.

Inefficient, poorly maintained/operated sanitation infrastructure

Information on this category was not readily available. Individuals affected by these problems were mostly included in DWAF's database as people that do not have access to services that meet minimum RDP requirements. This category did therefore, not contribute significantly to the overall rating. It should however be retained in future prioritisation processes as it is expected that this category will become more significant as the level of services increases.

Use of water for domestic purposes after limited treatment

Drinking of surface water after partial treatment did not explicitly contribute to the overall rating. DWAF's data focussed on people that do not have access to water supplies meeting RDP criteria and included groundwater sources. The necessary adjustments were made where information on the percentage use of groundwater was available. However, it is proposed that this attribute be included in future prioritisation processes as water and sanitation services are increasing and information may become more available in future.

Irrigation of crops to be consumed raw

It was very difficult to obtain information on this aspect. On advice of the Agricultural Research Council it was decided to include all areas where surface water is used for irrigation of vegetables, and to adjust the priority value.

 

10.3 Top 10 Priority Areas

The status of basic domestic water supply and sanitation services mentioned in this report represents the status as in 1994. Surface water in the following ten areas (in order of priority) were identified as having the highest potential health risk due to faecal pollution, namely (see map 4);

No 1: T31-T36. The main reason for this area having the highest potential health risk ranking is the fact that the majority of individuals living in the area did not have access to treated water for domestic use and were without any sanitation infrastructure. The people in this area live in a large number of small settlements in the area. The area falls within the boundaries of the old Transkei and major towns in the area are Kokstad, Matatiele, Maclear and Port St. Johns. The main streams in this area are the tributaries of the Mzimvubu river which ultimately flows into the Indian Ocean at Port St. Johns.

No 2: B51-B52. The high priority ranking of this area was also (as with T31-T33) due to a combination of a large number of people living in small settlements, with no formal domestic water supply and without any sanitation infrastructure. The Olifants river splits the area in two with all streams in both areas ultimately draining into the Olifants river. The section of the Olifants river that falls within this potential high risk area starts at the point where the Elands river merges with the Olifants river and stretches for approximately 90 km downstream. There are no major towns in this area, although there are a number of larger settlements, like Phokwane, Moletlane, Manane Maroge, Ga Marishane, Mahlakole, Mphanama and Lebowakgomo.

No 3: A23k. The main contributor to the high priority ranking of this area was the lack of purified water for domestic use. The main river in this area is the Sand river which flows through Ga-Rankuwa after which it becomes the Tolwane river which then flows through Kleinfonteinstat and eventually draining into the Moretele river.

No 4: A23jf. This potential high risk area borders the above (A23k) area on the North-Eastern side. This area had the same contributing health risk factors as in the above area, but in this area the lack of proper sanitation facilities contributed more towards the high ranking than in the above case. The Tswane river flows through this area, including Swartbooistat and Makapaanstat and then ends up in the Moretele river which flows into the Klipvoordam. The last 40 km of the Apies river before it merges with the Tswane river is also included in this potential high risk area.

No 5: B31d-j. This area's high priority ranking was mainly due to a very high percentage of people in the area without proper sanitation infrastructure. All the streams and rivers in this potential high risk area drains into the section of the Elands river that flows from the Rust de Winter dam into the Olifants river. The Elands river flows through settlements like Mapoch and Siyabuswa just below the Rhenosterkop dam.

No 6: B82d-h. In this potential high risk area both a lack of proper sanitation facilities (biggest contributor) and a lack of purified water for domestic use contributed to the high health risk rating of the area. In this area chicken farming also contributed, but to a lesser extent. The main drainage river in this area is the Klein Letaba up to the point where it joins the Nsama river. Other tributaries to the Klein letaba is the Middel Letaba and it's tributaries. Some of the main settlements around these rivers are Rotterdam, Middelwater, Hanthabala, Raphahlelo and Giyani.

No 7: C81f. This area had a major shortage of proper sanitation infrastucture. The area mainly falls within the old Qwa Qwa area and include towns and settlements like Phuthaditjaba, Witsieshoek, Thababosiu, Mafikeng and Monontsha. The main drainage systems are the Namahadi and Elands rivers and all their tributaries, ending about 15 km downsteram of the confluence of the Namahadi and Elands rivers.

No 8: V31-V33. A very high number of people in this area was in need of purified water for domestic use and were without proper sanitation facilities. The drainage system consists of the entire stretch of the Buffels river and all it's tributaries up to the point where it flows into the Tugela river. Major towns in this area are Newcastle, Dundee and Utrecht.

No 9: W21d-l. As with most of the above areas this area was one of the top ten potential high health risk areas due to a combination of a large number of people in this area that were in need of purified water for domestic use and the large number of people without proper sanitation facilities. The main drainage river is the section of the Wit Mfolozi starting about 30 km downstream of the Klipfontein dam up to the point where it joins the Mfolozi river. Main towns and settlements in this high health risk area is Ulundi, Babanango, Mkhazane and Esigodini.

No 10: X24a-c. This area has a very high population density (more than 6000 people/km2). A large percentage of people did not have proper sanitation infrastructure or a sufficient supply of purified water for domestic use. The main drainage river in this potential high health risk area is the entire stretch of the Nsikazi river up to the point where it merges with the Crocodile river. The two main settlements in the area are Matsulu and Ngodini.

 

11. CONCLUSION

The SMART methodology proposed in the conceptual design of the NMMP proved to be a feasible option to identify and objectively prioritise areas in South Africa where the microbial water quality is likely to have a severe impact on human health. Use of water in these areas for drinking, recreation, or irrigation of edible crops could pose a serious health threat, especially in rural areas where communities depend on water that receives limited or no treatment.

The prioritisation enables the Department to accommodate resource constraints by making it possible to implement the monitoring programme in a phased manner.

In the light of the increasing threat of faecal pollution of South Africa's water resources it is important to continue with the next phase namely the implementation of the monitoring programme in the identified Potential high risk areas. The information generated by the programme will enable the Department to report regularly, on a national scale, on the status and trends in terms of microbial water quality and the potential health risk to sensitive water users. This information will not only help create public awareness of the potential health risks of using faecally polluted water but will also assist water resource managers to assess the effectiveness of measures to protect water resources against faecal pollution.

 

12. RECOMMENDATIONS

i) There must be existing capacity in the area. This means the availability of laboratories that would be able to analyse the samples according to the prescribed methods. There must also be people that will be willing and able to do the sampling.

ii) There should be an inherent willingness by other role players to become involved (such as the Department of Health).

iii) It must be possible to identify factors which may enhance or impede the chances of success. These factors must be carefully considered and satisfactorily be resolved before implementation commences.

 

13 REFERENCES

Goodmin P and Wright G (1991) Decision Analysis for Management Judgement. John Wiley and Sons Ltd, Chichester, UK pp7 -36.

Institute for Water Quality Studies (1996) A National Microbial Monitoring programme to Assess Faecal Pollution of South African Surface Water resources: Design Framework. DWAF, April 1996.

Murray K (1999) National Microbial Monitoring Programme Implementation Manual. WRC Final Report, No K5/824/0/1.

Department of Water Affairs and Forestry (1998) National Water Act , Act 36 of 1998.

Venter SN, Kühn AL and Harris J (1998) A Method for the Prioritisation of Areas Experiencing Microbial Pollution of Surface Water. Paper presented at the IAWQ Conference, Vancouver, June 1998.


Appendix


Priority Assessment Values for Selected Potential High Health Risk Areas (see Map 4)

 

 

Priority assessment values for selected potential high health risk areas. Arranged from highest to lowest potential risk.

Pos

Rating

Area

Main drainage river/stream

Pos.

Rating

Area

Main drainage river/stream

1

6310281

T31-T36 (EC/K)

Mzimvubu & Itsitsa

21

1018506

V60 (K)

Sondags & Tugela

2

4736623

B51-B52 (NP)

Olifants

22

886439

T11 (EC)

Xuka & Mbashe

3

2073985

A23k (NW)

Sand & Tolwane

23

884942

C52b-d (F)

Modder & Rhenosterspruit

4

1927944

A23jf (NW)

Tswane & Moretele

24

859229

W22b-l (K)

Swart Mfolozi & Mfolozi

5

1724073

B31d-j (F/G/M)

Elands & Gotwane

25

840611

V12-V14 (K)

Klip & Tugela

6

1604872

B82d-h (NP)

Middel & Klein Letaba

26

833979

C31-33(NC/NW)

Harts & Droê Harts

7