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A Cultural Health Index for Streams and Waterways

Foreword

Acknowledgements

Executive Summary

1 Introduction

2 An Iwi Perspective on Freshwater and Its Management

3 Study Design

4 Calculating the Cultural Health Index

5 Applying the Cultural Health Index

6 Combining Cultural and Scientific Perspectives

7 Conclusion

Glossary

References

Appendix 1: Draft River Health Assessment Form

Appendix 2: Data Collected at Five Sites

Appendix 3: Recommended Recording Form for Future Use

Appendix 4: Questions Asked

4 Calculating the Cultural Health Index

Traditional association, mahinga kai and stream health are the three components that make up the Cultural Health Index. To derive the index at a particular stream site, first iwi association is identified, then mahinga kai values are assessed, and finally cultural stream health is evaluated. Almost all the necessary data for these measures are derived from the recording forms. The components of the CHI are first outlined below and then dealt with in detail in sections 4.1 to 4.3.

Component 1: stream sites are classified according to traditional association and intention to use in the future.

• Is there a traditional association between runanga and the site? Sites of traditional significance are assigned an 'A'. Sites that do not have a traditional association are assigned a 'B'.
• Would Māori come to the site in the future? Whether the runanga would return to the site or not is also recorded. If the runanga would return, the site is awarded a 1, and if not, a 0.

Component 2: sites are evaluated for the following mahinga kai features. Each feature is rated 1-5 and the mahinga kai score is the average of the four 1-5 ratings (1 is poor and 5 is the highest mahinga kai rating).

• How many mahinga kai species are present? This requires identifying the mahinga kai species that are present now.
• Are the mahinga kai species that were gathered in the past still here? This enables a comparison between the mahinga species that were gathered historically with the species that are present now.
• Are the mahinga species accessible for gathering? Accessibility includes physical access and legal access.
• Would Māori come to the site in the future? This component is the same as the second part of component 1 above. If the runanga would return, the site is awarded a 5, and if not, a 1.

Component 3: sites are evaluated for cultural stream health. First, the average scores for the runanga team members were calculated for 18 indicators of stream health at each site. Then, using a series of criteria, the list of indicators was condensed to a set of five that effectively encapsulates overall stream health (as assessed on the recording form). The average score for all included indicators provides the cultural stream health measure (1 is poor and 5 is the highest cultural stream health rating). The method of narrowing the set of indicators to five (principally through data analysis and validation by groups of iwi members) is described below.

Overall index: the overall three-part Cultural Health Index is expressed as shown in terms of the three components. For example, a stream may be given an index of:

A-0 / 2.1 / 4.2

where:

• A identifies the site as traditional (rather than a B for non-traditional)
• 0 indicates that Māori would not return to this site in the future (1 indicates they would return)
• 2.1 is the mahinga kai score (score of 1-5)
• 4.2 is the overall evaluation of stream health (score of 1-5).

4.1 Component 1: traditional association

The selection of sites to be monitored enables Māori to choose sites that are valued because of their traditional significance and special characteristics.

It was important that the CHI distinguish between traditional and contemporary sites. Preservation of valued traditional sites is an important task for those individuals who are mandated as the kaitiaki. Protecting traditional sites also makes a significant contribution to preserving cultural identity. The first part of the traditional association component of the CHI is therefore a classification along these lines:

• A - means the site is one that was chosen by Māori because it is a traditional site
• B - means that the site is not traditional.

It is essential that the traditional association component also reflects whether Māori believe they would or would not visit a site in the future. It is of little value having a traditional site valued highly because of the many mahinga kai species present and the water being free from physical pollution if Māori will not actually go there.

One example that highlights the different perspectives of Māori and non-Māori is the specification of water standards and the definition of water pollution. Māori spiritual values with respect to drinking water include standards and perceptions of pollution that may conflict with scientific measures. For example, 'drinking-water standard' may be scientifically defined as carrying contaminants, but at a level that is not toxic. In other words, a certain level of degradation can occur. In contrast, Māori would require drinking water to be protected from physical and spiritual pollution, which requires an absolute prohibition on certain discharge activities (Ministry for the Environment, 1997).

Including a question about whether or not Māori believe they would visit the site in the future enables them to consider the site in the context of their many other beliefs and values.

The second part of the traditional association component of the CHI is the question in the recording form that asks: Would you use this site in the future?

• No scores 0
• Yes scores 1.

4.2 Component 2: the mahinga kai measure

Qualities that help describe the mauri of a waterway include its life-supporting capacity, and the abundance, diversity and condition of the resources it supports. When assessing sites, Māori are likely to request sufficient quantities of water, of a quality appropriate for the maintenance of healthy mahinga kai resources and their related cultural values (Ministry for the Environment, 1997). As previously stated, a consideration of mahinga kai incorporates the ability to access the resource, the health of the site where gathering occurs, the abundance and condition of species gathered, the health of the site where gathering occurs, and the activity of gathering. It also requires that resources be accessible to Māori and in a condition whereby they are fit for cultural use. It was essential that the Index encapsulated the many facets of mahinga kai.

The mahinga kai component of the CHI was designed to incorporate four different aspects that are central to the continuity of cultural practices with respect to mahinga kai:

• the presence and abundance of mahinga kai species at a site
• the ability to harvest the same species as in the past from sites of traditional significance
• the ability to access a site for the harvest of mahinga kai
• the perception by Māori that the site can be used as it had been in the past.

To combine the four aspects of the mahinga kai component, each was rated on a 1-5 scale and then the four 1-5 scores were averaged to give a single 1-5 mahinga kai rating. The follow sections explain how these aspects are addressed in the mahinga kai component of the index.

4.2.1 Presence of mahinga kai species at sites now

This part of the mahinga kai component of the CHI requires the compilation of a list of mahinga kai species (plants, birds, and fish) present at each of the sites. When assessing each site, runanga members were asked to compile a list of bird and plant species present. Mahinga kai fish species were identified from electric fishing. A 30-metre reach was fished at each site and fish captured were identified and recorded before being returned alive to the water. The species lists were collated and a resource inventory prepared.

The number of mahinga kai plant, bird and fish species observed at each site then needs to be converted to a 1-5 scale. Sites that score a 5 indicate the high relative abundance of mahinga kai species in comparison to lower-rated sites within the catchment, whereas those that score a 1 are relatively sparsely populated.

Scores of 1-5 were assigned according to the number of species present. First, the site with the most species is identified. This number then needs to be converted to 5, the top of the 1-5 scale. For example: in our study the maximum number found at any one site was nine species. To convert the number to a score between 1 and 5 we added 1 and then divided the total by 2.

In effect this means that the best site in its current condition sets the baseline for comparison. This was appropriate given that a number of relatively unmodified sites are found in the Taieri and Kakaunui catchments. However, it does raise questions if none of the sites are in their original state. The project team is reviewing this aspect.

By adding 1 to the number of species for all 46 sites and then dividing by 2, the following scores were obtained:

• no mahinga kai species present - scores 1
• three species present - scores 2
• five species present - scores 3
• seven species present - scores 4
• nine or more species present - scores 5.

4.2.2 Presence of mahinga kai species at traditional sites

Accessing traditional records enables the identification of species sourced from traditional sites. As noted previously, the principal means of compiling lists of species traditionally sourced from an area are:

• written archives and journals
• evidence presented in support of Tribunal claims
• Māori Land Court records
• interviews with whanau members, in particular kaumatua
• community records.

This historical information can then be compared with the mahinga kai species present at the site today. Cultural continuity means that greater value will be assigned to sites of traditional significance that continue to support the mahinga kai species that were sourced from these sites in the past. A score of 1-5 is assigned, based on the number of species of traditional significance that are still present today:

• non-traditional site scores a 1
• none of the species sourced in the past are present at the site scores 1
• at least 25% of the species sourced in the past are still present scores 2
• at least 50% of the species sourced in the past are still present scores 3
• at least 75% of the species sourced in the past are still present scores 4
• all species sourced in the past are still present at the site scores 5.

4.2.3 Current access to mahinga kai at sites

The definition of 'mahinga kai' encompasses Māori being able to access the resources they want to gather. 'Access' covers both legal and physical access. Physical barriers may include it being too far to travel to the site, or too steep or dangerous to get to a site.

Legal barriers may include having to ask the landowner for permission or encountering locked gates. Although a number of species may be present at a site, if there is no access (and therefore no utility value), mahinga kai values cannot be ascribed.

A score of 1, 3 or 5 is assigned to each site based on the ability to access the site.

• no access is available scores 1
• either physical barriers or legal barriers make access difficult scores 3
• no barriers to access scores 5.

4.2.4 Will the site be used by Māori for mahinga kai?

As described in section 4.1, the question of whether Māori will use a site is fundamental to its mahinga kai status. Therefore, this aspect is also included here in the mahinga kai component of the CHI. In answer to the question: Would you come and use this site in the future?

• No scores 1
• Yes scores 5.

Please note that the scoring for component 2 differs from component 1 as all scores in this, the mahinga kai component, are between 1 and 5.

4.2.5 Calculating the mahinga kai measure

The mahinga kai score for a given site is determined by averaging the scores for each of the mahinga kai components. The scores for these components are derived from the recording form and electric fishing, except the score for the component described in section 4.2.2, which depends partly on historical information.

4.3 Component 3: cultural stream health measure

In addition to the many intangible qualities associated with the presence of a waterway, mauri can be tangibly represented in terms of some of its physical characteristics, including water clarity; the depth, velocity and volume of water flow; natural character; flora and fauna; continuity of flow from the mountain source of a river to the sea; and fitness of the waters and the resources supported for cultural usage (Ministry for the Environment, 1997).

To be effective, the cultural stream health measure must embody Māori values and produce consistent and repeatable results irrespective of the iwi members who use it and the streams it is applied to. Of the 21 original indicators of cultural stream health on the recording form, 18 were identified as potentially useful components of the cultural stream health measure. (River shape and Balance were removed after they proved difficult for runanga members to score consistently. Mahinga kai birds was removed so that mahinga kai values are reflected in component 2 and no mahinga kai values would appear in the cultural stream health measure. The two components of Indigenous species, on adjacent land and in riparian margins, were scored as a single measure).

The 18 indicators used to develop the cultural stream health measure of the CHI are listed below. Rather than discuss each indicator in the order it appears on the recording form, they have been grouped by topic. For instance, those relating to the river margins are presented together, as are those that relate to in-stream water quality.

River health values include an overall stream health measure - an all-encompassing measure made up of all the indicators that contribute to stream health. Correlation coefficients between each indicator and overall stream health are shown in square brackets.

For cross-referencing, the number of the indicator on the recording sheet is presented in italics after the numbering by topic used here.

4.3.1 Indicator categories

River health values

1. (21) Overall stream health (1-5; very unhealthy / very healthy) [1.0]
2. (19) Fish safe to eat (1-5; completely unsafe / completely safe) [0.91]
3. (17) Water safe to drink (1-5; completely unsafe / completely safe) [0.84]
4. (18) Would go fishing at the site (1-5; would not / great place to fish) [0.83]

Catchment scale

5. (1) Catchment land use (1-5; land and margins grazed / natural condition) [0.64]

Riparian river-margin scale

6. (16) Use of riparian margin (1-5; riparian zone grazed / natural) [0.65]

7. (4) Riparian vegetation (1-5; little or none / indigenous riparian vegetation) [0.54]

8. (5) Indigenous species (1-5; exotic vegetation on adjacent land and margins / indigenous vegetation on adjacent land and margins) [0.45]

9. (2) Riverbank condition (1-5; banks eroding / stable) [0.36]

In-stream physical characteristics

10. (8) Use of river - modification (1-5; evidence of modification / appears natural) [0.66]

11. (15) Sediment (1-5; sediment covering bed / bed free of sediment) [0.60]

12. (7) Riverbed condition (1-5; muds and sands / cobbles and gravels) [0.48]

13. (9) Use of river - takes and discharges (1-5; takes and discharges evident / no evidence) [0.39]

In-stream flow

14. (10) River flow - visible (1 or 5; no movement / movement visible) [0.58]

15. (11) River flow - audible (1 or 5; no sound / flow audible) [0.44]

In-stream water quality

16. (13) Water quality - pollution (1-5; foams or oils / none evident) [0.75]

17. (12) Water quality - smell (1 or 5; unpleasant odour / clean smell) [0.69]

18. (14) Water quality - discolouration (1-5; badly discoloured / clear) [0.61]

The measure of overall stream health (item 1) has particular significance in deriving a stream health measure. Every ecosystem health index is a human construct that depends on a subjective value of what is considered healthy. Thus, the cultural stream health measure derived in this study must encapsulate and be closely related to the overall measure of what runanga members consider healthy from their point of view.

Selecting the indicators that best express stream health from a cultural perspective involved the following steps:

1. Identify and remove value judgement indicators that are equivalent to overall stream health and that cannot be adequately defined or consistently measured.
2. Determine indicators from the various categories of indicators that are most strongly correlated with 'overall stream health' (catchment category, riparian river-margin category, in-stream physical category, in-stream flow category, and in-stream water-quality category).
3. Perform a stepwise multiple regression analysis to determine, in a rigorous statistical manner, which variables together account for most of the variation in 'overall stream health' at a site.
4. Compare the outcome of the multiple regression analysis in C with the variables selected in B and decide on a final set of indicators to include in the cultural stream health component of the CHI. Finally, average the scores for the selected indicators to provide the cultural stream health component at every site.

4.3.2 Selecting the indicators

(a) Identify and remove redundant health values

At step A, indicators 2, 3 and 4 (Fish safe to eat? Water safe to drink? Would go fishing?) were found to be very strongly correlated with overall stream health (correlation coefficients greater than 0.80). [A correlation coefficient of 0 means there is no relationship, whereas a value of 1.0 means the two factors are perfectly correlated.] Note that all four items are value judgements and are essentially measures of the same thing, indicating that the Māori concept of overall stream health is strongly related to the use of natural resources. For the purposes of developing a robust index of cultural stream health, indicators 2-4 will not be considered further.

(b) Identify indicators from a range of categories that correlate most strongly with overall stream health

Step B identified the following indicators from each category shown above as being most strongly correlated with overall stream health. These are listed below, together with their correlation with overall stream health. In the catchment category, only a single measure was available but it was strongly correlated with overall stream health. Two or more indicators were present in each of the other categories. Within a category, indicators were often highly correlated with each other and may be considered to be measuring essentially the same thing (e.g. in the water-quality category smell (0.77) and discoloration (0.71) were both highly correlated with pollution).

Reducing each category to a single indicator that is most highly correlated with overall stream health avoids problems of using several indicators of the same condition. The resulting indicators, by category, are as follows:

1. catchment scale: catchment land use [0.64]
2. riparian river-margin scale: use of riparian margin [0.65]
3. in-stream physical characteristics: use of river - modification [0.66]
4. in-stream flow: river flow - visible [0.58]
5. in-stream water quality: water quality - pollution [0.75].

(c) Stepwise multiple regression of health indicators

Step C involved a stepwise multiple regression of stream health indicators. Stepwise multiple regression is a statistical procedure that mathematically selects a reduced set of variables (from the 14 indicators considered in step A) that best account for the variation in a dependent variable (in this case, the overall health score). We used a full stepwise procedure, which adds variables one at a time in building an overall model. The first variable added is the one that explains the most variation in the dependent variable (i.e. has the highest correlation with overall stream health). This first variable will not explain all of the variation in the dependent variable, so there is 'residual' variation left unexplained. The stepwise procedure then adds another variable, specifically the one that accounts for the most residual variation after the first variable. The procedure continues in this manner until a set of variables is included in a model such that each one explains a significant portion of the variation in the dependent variable in the overall model.

Our stepwise regression analysis (setting the necessary statistical significance for inclusion of an indicator as p < 0.05) yielded the four indicators below, given in order of importance. When these four factors are taken together they account for an acceptable 76% of the variation in overall stream health at the sites:

1. water quality - pollution
2. use of riparian margin
3. use of river - modification
4. river flow - visible.

(d) Calculation of the cultural stream health measure

The conclusions from the above sections (b) and (c) are very similar, providing considerable confidence for our choice of indicators to include in the cultural stream health measure. Our subjective choice of individual factors from fivehabitat categories was the same as the result from the objective stepwise multiple regression analysis, except that the latter did not identify catchment land use as a significant component of the model. This is probably because catchment land use and use of the riparian margin were strongly correlated with each other (0.84). On this basis, we could have decided to omit catchment land use from our cultural measure. However, the holistic view of river systems held by Māori is such that it seemed more appropriate to retain catchment land use.

Calculation of the cultural stream health measure for each site involved calculating the average score for runanga members for each of the following indicators (each on a 1-5 scale), before calculating a grand mean for the five indicators together (again on a 1-5 scale):

1. catchment land use (1-5; land and margins grazed / natural condition)
2. use of riparian margin (1-5; riparian zone grazed / natural)
3. use of river - modification (1-5; evidence of modification / appears natural)
4. river flow - visible (1 or 5; no movement / movement visible)
5. water quality - pollution (1-5; foams or oils / none evident).

The recommended recording sheet with these five indicators included is found in Appendix 3.

4.4 Is the cultural stream health component of the CHI appropriate for streams of different sizes and for the different rivers?

We found no significant correlation between the cultural health component of the CHI and either stream order (1-2, 3-4, 5+) or river (Taieri, Kakaunui). This means that the tool developed is equally applicable to the different rivers and streams of different size. This is important because, had this not been the case, different tools would be needed for different circumstances.

4.5 How does the cultural stream health component of the CHI compare to Western scientific measures of stream health?

The CHI comprises three components, of which only the stream health component has Western scientific counterparts. To place the cultural stream health component of CHI in a broader perspective, we compared it with two Western scientific measures of stream health (see below). This comparison provides an effective way of identifying what iwi have to offer that is not currently incorporated into land and water resource management processes and decisions.

4.5.1 The Macroinvertebrate Community Index (MCI)

The Macroinvertebrate Community Index (MCI), widely used by regional authorities and researchers to assess stream health, is based on the presence or absence of certain types of invertebrate on the stream bed, which differ in their ability to tolerate pollution. Healthy streams have high values on the MCI (120 or above) whereas unhealthy streams have values as low as 80 or less. We used Otago Regional Council protocols to determine the MCI at all 46 stream sites.

4.5.2 The Stream Health Monitoring and Assessment Kit (SHMAK)

The Stream Health Monitoring and Assessment Kit (SHMAK) was developed as a tool for landowners to monitor the health of streams flowing through their properties, particularly in relation to changes to riparian or catchment land use, and it has been quite widely adopted by community groups working to improve stream health in both rural and urban settings. It is made up of a habitat component and an invertebrate component. Measurements of flow velocity, pH, temperature, conductivity, clarity, bed composition, deposits and bank vegetation over a 10-metre stream reach make up the habitat component. The invertebrate component is based on a simplified version of the MCI, incorporating just 17 invertebrate taxa.

The outcome of the SHMAK protocol is a verbal rating of very poor, poor, moderate, good, very good, and excellent health, which we converted to numerical values of 1, 2, 3, 4, 5, and 6 for statistical comparisons with the cultural stream health measure at the 46 sites.

4.5.3 Relationships between the three measures

The cultural stream health measure was significantly correlated with both the MCI (0.58) and SHMAK (0.49) (Figure 3). This indicates that the cultural stream health measure, like its Western scientific counterparts, successfully captures aspects of stream health.

The very strong relationship between the MCI and the cultural measure is particularly notable. This is because the MCI is based entirely on stream invertebrates whereas the cultural measure has no invertebrate component but assesses stream health from a Māori perspective on the basis of a combination of catchment, river-margin and in-stream characteristics. Streams judged by runanga members to be in poor health turn out to possess a set of invertebrate species that are tolerant of poor water quality.

The cultural stream health measure was less strongly correlated to the invertebrate component of SHMAK (0.36) than to the habitat component (0.70) (see Figure 3), which is not surprising given that the cultural measure is habitat-based. The invertebrate component of SHMAK is based on 17 indicator taxa, which differ in some respects to those incorporated in the MCI.

It is important to acknowledge that although the MCI and the cultural stream health measure correlated well, the cultural stream health measure is specifically designed to assess Māori values. While it represents a means of facilitating communication between resource managers and Māori, the MCI should not be seen as a surrogate for resource managers to consider the likely status of Māori values.

4.6 What is the relationship between cultural and Western scientific stream health measures and patterns of catchment land use?

Research in the Taieri catchment and elsewhere has established that land-use development in stream catchments, such as conversion from native vegetation to agriculture, can influence stream health by changing water chemistry, turbidity, temperature and the physical nature of the stream bed and banks, with consequences for stream life. It is therefore of interest to consider the relationship between the cultural stream health measure and land use in the stream's catchment, and to compare the performance of the cultural and Western scientific measures in this respect.

We used the University of Otago Stream Team's Geographic Information System (GIS) to determine the percentage of developed land for each stream catchment, defining developed land (DL) as the sum of bare ground, urban, pasture, and pasture plus riparian willows. A topical question in stream ecology is the scale at which stream health is influenced by land use. Is stream health influenced more by land use in the entire catchment (all the land draining into the headwaters that feed the site in question), or just in the riparian zone adjacent to the stream?

We address this question, and check how well the cultural and Western scientific measures of stream health encapsulate the land-use effect. We compare the relationships between the cultural stream health measure, MCI and SHMAK and land use using two scenarios:

• percentage developed land in the entire catchment above each site (DL1)
• percentage developed land in a 100-metre-wide riparian strip extending for just
  500 metres above each site (DL2).

There were negative relationships between percentage developed land at both scales and each of the stream health measures (as percentage developed land increased, the stream health measure scores decreased, as expected) (see Figure 4). Of all the relationships, the strongest was between the cultural measure and riparian development (-0.56) (see Figure 4f), with a lower correlation between the cultural measure and development in the entire catchment (-0.41) (Figure 4c). This may reflect the fact that runanga members focused their attention at each site on land use within their visual range. The MCI also performed well, but in this case showed a stronger relationship with catchment development (-0.51) (Figure 4a) than riparian development (-0.44) (Figure 4d). This suggests that invertebrate stream life is more strongly influenced by land development in the catchment as a whole. SHMAK performed poorly, with correlations of -0.25 at both scales (Figures 4b and 4e).

We conclude that the cultural stream health measure performs as well as the MCI in encapsulating the relationship between land development and stream health.

4.7 Stream health measures and iwi

4.7.1 The cultural stream health measure and iwi values

The values and perceptions of iwi form the basis of the cultural stream health measure. Kaumatua initially identified features of the catchment and stream that, from a cultural perspective, are fundamental to healthy streams. These features were assessed directly by runanga members at all stream sites. Because each feature is expressed at a broader level than Western scientific measures, flexibility was required in the assessment method we used. For instance, water quality is evaluated on the basis that the water appears polluted by foams and oils. While water quality is evaluated as a single feature, a number of considerations are clearly involved in arriving at the score. The selection of a 1-5 rating scale proved appropriate for assessing the broader-scale features of cultural significance and for use by runanga members. The approach is considered to be in keeping with the way stream health is evaluated culturally.

4.7.2 MCI and iwi values

The MCI requires stream invertebrates to be sampled and identified and an index to be calculated. Training, equipment and laboratory facilities are integral to the MCI, and this effectively restricts its use to researchers and land and water managers. Based as it is on benthic invertebrates, the MCI does not incorporate iwi values.

4.7.3 SHMAK and iwi values

Developing a stream health indicator for use by community groups involved the integration of a habitat and an invertebrate component. Instruments are needed to measure habitat features such as water velocity, temperature, clarity, pH and conductivity, and invertebrates are sampled and indicator species identified and counted over a 10-metre reach in the field. Both components of SHMAK are based on Western scientific measures of stream health. Given the requirement for detailed measurements of stream habitat and the identification of benthic invertebrates, SHMAK does not currently incorporate iwi values.

4.8 Incorporating tangata whenua values into SHMAK

As this study proceeded we considered whether it would be feasible to incorporate iwi perspectives and values into SHMAK. At the beginning of the project we anticipated meeting this objective. However, as the project progressed and we analysed data sets and developed the cultural stream health measure, it became clear that the two sets of values are on such different scales that it would be inappropriate to incorporate an iwi component into SHMAK.

Whereas iwi values are expressed at a broader holistic level, SHMAK components are defined at a detailed Western scientific level and are measured using instruments. Furthermore, invertebrate sampling and counting was considered by runanga participants in this project as foreign to the way iwi evaluate stream health.

Our analysis of cultural and Western scientific data sets in this study further indicates that the cultural measure reflects the level of land development in the catchment more closely than does SHMAK. The holistic Māori view of stream health would seem to be better served by a measure that is closely related to the overall state of the catchment.

Finally, the CHI comprises three interrelated components: the traditional status of the site, the mahinga kai component and the stream health component. Incorporating aspects of one component into a Western scientific measure could compromise the integrity of the CHI. From a cultural perspective, the CHI can be easily applied as a whole and produces meaningful results that embody most of the aspects of stream health that are valued by iwi.