2021 04 16 JWS WQ Experts.pdf

IN THE ENVIRONMENT COURT OF NEW ZEALAND
AUCKLAND REGISTRY

I TE KŌTI TAIAO O AOTEAROA
TĀMAKI MAKAURAU ROHE

IN THE MATTER
of the Resource Management Act 1991

AND
of an appeal under clause 14 of Schedule 1 of the Act

BETWEEN
MINISTER OF CONSERVATION

MANGAWHAI HARBOUR RESTORATION SOCIETY

THE NEW ZEALAND REFINING COMPANY LIMITED

ROYAL FOREST AND BIRD PROTECTION SOCIETY
OF NEW ZEALAND INCORPORATED

Appellants

NORTHLAND REGIONAL COUNCIL

Respondent

JOINT WITNESS STATEMENT OF FRESHWATER ECOLOGY EXPERTS
TOPIC 5: WATER QUALITY
16 APRIL 2021

1

Joint Witness Statement of Freshwater Ecology Experts
Attendees
Kathryn Jane McArthur for the Minister of Conservation and Royal Forest & Bird
Protection Society of New Zealand Inc
Dr Roger Graeme Young for Northland Regional Council
Rachael King recorder on 14 April 2021
Trish Simpson recorder on 16 April 2021 for the first half of conferencing.

Introduction and code of conduct
1.
This  Joint  Witness  Statement  relates  to  freshwater  ecology  issues
resulting from appeals by the Minister of Conservation (MOC) and Royal
Forest & Bird Protection Society of New Zealand Inc (RFB) seeking that
additional water quality attributes be included in the Proposed Regional
Plan for Northland (Proposed Plan).  The appeals are part of the Topic 5
– Water Quality hearing topic (Topic 5).
2.
Dr Young prepared a brief of evidence dated 12 March 2021 for Topic 5.
Ms McArthur prepared a brief of evidence dated 26 March 2021 for Topic
5.    The  experts’  qualifications,  experience,  assumptions,  methods  and
facts relied on are set out in their respective briefs of evidence.
3.
The  experts  have  also  been  guided  by  the  summary  prepared  by  the
parties of:
a)  relevant provisions of the Regional Policy Statement;
b)  the Proposed Plan’s existing water quality standards;
c)  the relief sought by MOC and RFB; and
d)  a  summary  of  the  way  water  quality  standards  are  applied  in  the
Proposed Plan.
4.
The summary is attached as Appendix 2 to this JWS.
5.
The experts confirm that they have read the Environment Court Code of
Conduct  for  expert  witnesses  and  Appendix  3  –  Protocol  for  Expert
Witness Conferences and agree to abide by it.

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Agreed statement of facts
6.
Water  quality  and  ecological  data  from  across  Northland  indicates  that
many  rivers  are  in  a  degraded  state  with  high  concentrations  of
phosphorus, faecal indicator bacteria and poor water clarity.
7.
Council  reporting  on  the  state  of  Northland’s  rivers  (Nicholson  and
Parquin 2018) states: “On a national scale, our rivers compare poorly for
phosphorus,  ammoniacal  nitrogen,  faecal  contamination,  turbidity  and
visual clarity”.
8.
For  ammoniacal  nitrogen  and  nitrate  nitrogen,  most  sites  are  above
Australia and NZ guidelines indicating current nutrient concentrations are
potentially stimulating aquatic plant and algal growth (although direct toxic
effects of ammoniacal nitrogen and nitrate nitrogen are unlikely at current
concentrations).
9.
Macroinvertebrate communities are indicative of many sites experiencing
moderate to severe pollution/enrichment.
10.
Nuisance periphyton is relatively rare in Northland (three of 36 monitoring
sites  exceeded  the  periphyton  bottom  line)  but  occurs  in  some  hard-
bottomed rivers.
11.
There  is  evidence  of  declines  in  macroinvertebrate  community  index
scores  over  the  last  ten  years  at  16  monitoring  sites,  although  likely
improvements have been identified at six sites.
12.
The majority of monitoring sites in Northland grade a D band for E. coli.
E. coli concentrations at reference sites are typically high, suggesting that
naturalised sources of faecal indicator bacteria may be one contributing
factor to the elevated concentrations.  Microbial (faecal) source tracking
at a selection of river sites has shown that 66% returned positive markers
for  ruminant  contamination,  24%  for  wildfowl,  7%  for  plant  decay,  2%
returned  indeterminate  results  and  1%  for  human  contamination
(Nicholson and Parquin 2018).
13.
Above half of the monitoring sites would be in the NPS-FM D-band based
on  dissolved  reactive  phosphorus.    Increases  in  concentrations  (i.e.
degrading trends) of DRP and total phosphorus (TP) have been observed
at most sites over the last 10 years.

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Conference outcomes
The  experts  understand  Policy  H.3.1  manages  point  source  discharges  and
decision makers will be guided by Policy D.4.1, therefore, their answers to the
following questions take this into account.
What  interim  attributes  are  needed  to  provide  for  a  good  state  of  ecosystem
health in Northland?
14.
The  experts  agree  that  there  are  a  variety  of  stressors  associated  with
discharges that need to be considered, including temperature, sediment,
organic waste, nutrients and toxicants.
15.
Ecosystem health incorporates five components:
a)  water quantity;
b)  water quality;
c)  aquatic life;
d)  physical habitat; and
e)  ecological processes.
16.
Whilst the experts understand that this  Plan takes an interim approach,
and that not all attributes for all components may be included at this time,
the  experts  agree  that  there  are  benefits  in  including  a  breadth  of
attributes that cover more than one component of ecosystem health.
17.
The  experts  have  provided  a  table  of  their  recommended  attributes  for
ecosystem health and human contact as Appendix 1 to this JWS.
18.
The experts agree that the attributes in Table 20 (nitrate toxicity, ammonia
toxicity, temperature, dissolved oxygen and pH) are suitable as drafted in
the appeals version of the Proposed Plan.
19.
The  experts  agree  that  there  is  a  mixture  of  assessment  approaches
within  the  attributes  suggested  by  Ms  McArthur  in  her  evidence.    For
example, the attributes in Table 20 and the recommended periphyton and
toxicants, metals and metalloids attributes are assessed by comparing the
upstream  and  downstream  states  by  reference  to  NPS-FM  or  guideline
numeric values.  Ms McArthur describes these as ‘state attributes’ in her
evidence.  The remaining attributes are a direct assessment of the degree

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of  change  between  upstream  (control)  and  downstream  (impact)  sites,
which Dr Young describes as ‘change standards’ in his evidence.
Periphyton
20.
The  experts  agree  that  periphyton  blooms  are  potentially  caused  by
discharges  and  periphyton  assessment  is  useful  to  manage  this  risk  to
ecosystem  health.    It  is  Dr  Young’s  opinion  that  periphyton  attribute
compliance could be assessed relatively easily for an existing discharge,
but  there  is  a  challenge  in  assessing  compliance  relating  to  a  new
discharge.    In  Ms  McArthur’s  opinion,  applicants  for  resource  consents
are required to assess the potential affects of their discharges, and where
there is a risk of nuisance periphyton growth (i.e., hard bottom rivers), an
assessment  could  and  should  be  undertaken  at  least  against  national
bottom lines.
21.
Dr  Young  recognises  that  it  is  relatively  easy  to  predict  compliance  for
attributes  that  are  directly  related  to  a  new  discharge’s  constituent
concentrations and volumes, but more challenging for attributes such as
periphyton  that  are  influenced  by  other  factors  not  associated  with  the
discharge.    This  challenge  is  evident  when  considering  the  compliance
statistic requires monthly monitoring for 3 years, which is impossible for a
discharge that is not in place yet.
22.
In Ms McArthur’s view the likelihood and risk of a non-compliance can be
established  through  assessing  baseline  nutrient  concentrations  and  the
estimated  nutrient  concentrations  of  the  discharge.  In  her  view,  policy
D.4.1 provides adequate guidance to decision makers to implement the
periphyton attribute on an interim basis and therefore it is appropriate to
include periphyton as an attribute in the plan.
23.
The  experts  identify  that  there  are  some  uncertainties  in  relation  to
inclusion of periphyton in the plan, such as:
a)  The
coarse
nature
of
relationships
between
nutrient
concentrations  and  periphyton  biomass  which  means  that  site
specific predictions lack precision.
b)  Uncertainty in relation to the number and location of hard bottom
rivers  in  Northland  means  the  scale  of  potential  nuisance
periphyton growth from discharges is unknown.

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c)  The  experts  have  no  information  on  the  potential  number  and
scale  of  new  discharges  that  may  result  in  nuisance  periphyton
growth over the interim plan period.
24.
In Ms McArthur’s opinion, including periphyton as an attribute in the plan
is unlikely to be an onerous burden on consent applicants, given the scale
of the issue.
25.
Dr Young sees value in periphyton as an attribute in the plan, but believes
this would be better included as a guideline for new discharges rather than
a strict standard.
26.
Dr Young has analysed periphyton biomass data and compared hill and
lowland  sites,  as  defined  by  Snelder  (2015),  and  found  no  difference
between them.  On this basis, the experts agree that the more nuanced
approach of separating other  rivers  into  ‘hil ’  and ‘lowland’  classes  with
different periphyton bands is not supported by the data.  Therefore, the
experts agree that periphyton biomass could be included in the Plan using
the coarser approach of A band for outstanding rivers and C band for all
other  rivers,  with  the  proviso  that  exceedances  as  a  result  of  naturally
occurring processes will not be considered ‘non-compliant’.
27.
With respect to periphyton the experts agree that cover and biomass are
complementary measures that can be used to manage periphyton issues.
The  experts  agree  that  the  NPS  FM  approach  could  be  adopted  in
Northland.  In this approach periphyton biomass is the primary attribute
for  measurement  where  there  are  risks  of  periphyton  blooms,  while
periphyton  cover  can  be  monitored  at  low  risk  sites  with  assessment
upgraded  to  include  periphyton  biomass  if  levels  are  approaching
periphyton thresholds.
28.
Ms McArthur maintains that periphyton cover is an important attribute for
human use e.g., recreation and this is discussed below.
Temperature change
29.
The experts agree that the temperature change standard described in Ms
McArthur’s evidence is useful and should be included in the plan.

6

QMCI change
30.
The experts agree that including a macroinvertebrate attribute in the plan
is suitable to provide for the aquatic life component of ecosystem health.
31.
Dr Young’s concern about a lack of QMCI data in Northland that he raised
in  his  evidence  has  been  addressed  since  QMCI  data, that  he  was  not
aware of when he wrote his evidence, has now been provided. Therefore,
Dr Young believes that either the QMCI or the MCI are suitable attributes
for inclusion in the plan with a 20% change threshold.
32.
Ms  McArthur  prefers  the  use  of  QMCI  for  the  reasons  set  out  in  her
evidence.
Toxicants, Metals and Metalloids
33.
The  experts  agree  that  toxicants,  metals  and  metalloids  are  suitable  to
include  in  the  plan  with  respect  to  ecosystem  health  as  set  out  in  Ms
McArthur’s evidence.
Visual Clarity change
34.
The experts agree that visual clarity change is a suitable attribute to be
included in the plan.
35.
Dr Young highlights that only a small discharge of sediment could breach
the 20% threshold proposed by Ms McArthur for outstanding rivers.  He
thinks that this clarity threshold is suitable if maintenance of clarity is the
significant value to protect, but considers that a 30% threshold, or focus
on sediment concentrations or loads, is a better approach if management
of sediment deposition in downstream water bodies is the significant value
to protect.
36.
Ms  McArthur  generally  agrees  with  the  above  statement  but  in  her
opinion,  given  the  sediment  issues  in  Northland,  the  stringent  20%
threshold is more suitable for protecting the values of outstanding rivers.
Deposited Fine Sediment Change
37.
The experts agree that a deposited fine sediment attribute is suitable for
inclusion in the plan as described in Ms McArthur’s evidence. The experts
note that this attribute would only apply in hard bottomed wadeable rivers.

7

What  compliance  metrics  and  periods  of  records  are  needed  for  these  interim
attributes?
38.
The  experts  agree  that  the  compliance  metrics  and  periods  of  record
described in the table attached as Appendix 1 to this JWS are suitable.

What  interim  attributes  are  needed  to  provide  for  safe  human  contact  in
Northland?
E. coli
39.
The  experts  recognise  there  is  a  risk  of  microbial  pathogens  from
discharges effecting human contact values in Northland.
40.
For wastewater discharges there is potential for the relationship between
indicators and pathogens to be altered by the treatment process and for
E.  coli  to  not  adequately  indicate  the  risk  of  viruses  and  protozoa.
Therefore, E. coli is not necessarily a good indicator of health risk in water
bodies  affected  by  wastewater  discharges  (e.g.,  municipal  sewage
discharges).    Quantitative  microbial  risk  assessment  (QMRA)  is
considered  best  practice  to  assess  public  health  risk  from  these
discharges.
41.
The experts recognise that E. coli is relatively high in reference sites and
that  this  may  be  because  of  natural  occurrences  to  some  degree.
Therefore, it may not be appropriate to apply the E. coli A band attribute
states from Table 9 of the NPS FM to outstanding rivers as set out in the
evidence of Ms McArthur.
42.
The  experts  agree  that  the  C  band  (yellow)  attribute  state  for  E.  coli  is
suitable for all rivers (including outstanding rivers) in Northland to manage
risks to human contact values.
43.
Where a discharge exceeds the E. coli standard there is the ability for a
consent applicant to undertake more rigorous assessment of the risks to
public health using tools such as QMRA.  This may be warranted where
there  is  a  large  municipal  or  industrial  discharge  near  a  waterbody
associated with high human use values.  The experts acknowledge that
they  do  not  have  the  expertise  to  stipulate  whether  a  QMRA  or  similar
method should be specified in the Plan, but they recognised that such an

8

assessment  could  be  used  to  demonstrate  that  the  discharge  will  not
exacerbate the risk to the health of water users.
Periphyton cover
44.
The experts agree that including an attribute associated with periphyton
cover  would  help  manage  the  effects  of  periphyton  on  human  contact
values and that 30% weighted composite cover is a suitable threshold.
45.
The experts agree that the compliance statistic should be  the seasonal
maximum weighted composite cover on visible stream bed in a reach (1
November – 30 April), as specified in Matheson et al. (2016).

What  compliance  metrics  and  periods  of  records  are  needed  for  these  interim
attributes?
46.
The  experts  agree  that  the  compliance  metrics  and  periods  of  record
described in the tables attached as Appendix 1 to this JWS are suitable.
Agreed matters
47.
The experts:
a)  Agree  that  the  water  quality  standards  relate  to  discharge
management in the plan and are designed to avoid negative impacts
on water quality and ecosystem health associated with discharges.
b)  Recognise and realise that these attributes just relate to discharges.
48.
The  experts  agree  that  sediment  management  is  important  for
maintaining ecosystem health in waterbodies in Northland, but this issue
requires management beyond just discharges.
49.
The  experts  have  identified  within  the  data  for  E.  coli  (and  possibly
periphyton)  that  at  times,  sites  that  are  in  reference  condition  (e.g.,
relatively  unimpacted  by  human  activities),  some  of  which  are  in
outstanding rivers, are unable to meet the standards recommended below
due to naturally occurring processes.  The experts recommend including
the proviso to all the standards in the Plan: “Unless naturally occurring
processes as defined in the NPS FM (2020) prevent the waterbody from
achieving the standard.”

9

Dated this 16th day of April 2021

Kathryn McArthur

Dr Roger Young

10

APPENDIX 1. WATER QUALITY STANDARDS FOR H.3.1 OF THE PRPN RECOMMENDED BY THE EXPERTS
Table 20: Water quality standards for ecosystem health and human contact in rivers.1
Attribute
Unit
Compliance Metric
Outstanding rivers
Other rivers
Expert’s comments
Ecosystem health

Periphyton biomass
mg chl-a/m2
Exceeded by no
Band A
Band C
Dr Young’s view is
(chlorophyll a)
more than 8% of

that this would be
samples (default

Numeric
better included as a
class rivers).
Numeric
guideline for new
Numeric
Numeric
Attribute

Attribute State
discharges rather
Attribute
Attribute
State
Exceeded by no
(Productive
than a strict
State
State
(Default
more than 17% of
Class)2
standard
(Default
(Productive
Class)
samples in
Class)
Class)2
productive class
>120 and ≤
>120 and ≤ 200
rivers.2
≤50
≤50
200 (C)
(C)

Based on monthly

samples collected
over three years
Temperature
Degrees Celsius
Summer period
≤1oC
≤3oC

change*
measurement of the

Cox-Rutherford

Index (CRI),

averaged over the
five (5) hottest days
(from inspection of a

1 Unless naturally occurring processes as defined in the NPS FM (2020) prevent the waterbody from achieving the standard.
2 Rivers are categorised as productive according to types in the River Environment Classification (REC). Productive rivers are those that fall within the REC
“Dry” Climate categories (i.e., Warm-Dry (WD) and Cool-Dry (CD)) and the REC Geology categories that have naturally high levels of nutrient enrichment due
to their catchment geology (i.e., Soft-Sedimentary (SS), Volcanic Acidic (VA) and Volcanic Basic (VB)). Therefore, productive rivers are those that belong to
the following REC defined types: WD/SS, WD/VB, WD/VA, CD/SS, CD/VB, CD/VA.

11

continuous
temperature record).
QMCI (wadeable
Index value
Equivalence test
≤20%
≤20%
Dr Young indicated
rivers) change*
between five (5)
(not more than 20%
(not more than 20% reduction)
that the QMCI or
replicate 0.1m2
reduction)

MCI would be
Surber samples

equally suitable
(protocol C3 hard-
attributes
bottomed
quantitative) or
equivalent sampling
effort for soft-
bottomed rivers
using protocol C4
soft-bottomed
quantitative as per
Stark et al. (2001)
from each upstream
and downstream site
Toxicants, metals
Default guideline
Maximum
99% species protection
95% species protection

and metalloids
value (DGV) for

(excludes nitrate or
toxicant, metal or

ammonia toxicity)
metalloid in

Australian and New

Zealand Guidelines

for Fresh and

Marine Water
Quality 2018:
ANZG (2018)
Visual clarity
Metres
Maximum
≤20%
≤30%
Dr Young notes this
change*

clarity threshold is
Not more than 20%
Not more than 30% decrease in
suitable if
decrease in black disc or
black disc or equivalent
maintenance of
measurement
clarity is the

12

equivalent measurement
significant value to

protect, but
considers that a
30% threshold, or
focus on sediment
concentrations or
loads, is a better
approach if
management of
sediment deposition
in downstream
water bodies is the
significant value to
protect.
Deposited fine
Percent cover
Sample average
≤10%
≤10%

sediment change -
(all transect

hard-bottomed
observations at each
(Not more than 10%
(Not more than 10% increase in
wadeable rivers
site using SAM2
increase in % cover)
% cover)
change*
protocol Clapcott et

al. 2011)

Human Contact

Escherichia coli (E.
E. coli/100ml
Does not exceed
C (Yellow) band
C (Yellow) band

coli)
any of the four
attribute states in
Table 9 of the NPS
FM (2020)
E. coli in primary
E. coli/100ml
95th percentile
≤540 All rivers
≤540 All rivers

contact sites during
the bathing season
Periphyton cover
Percent cover
Seasonal maximum
≤30%
≤30%
Dr Young’s view is
(periphyton
weighted composite

that this would be
cover on visible
better included as a

13

weighted composite
stream bed in a
guideline for new
cover – periWCC)
reach (1 November
discharges rather
to 30 April)
than a strict
standard

*Note: Change is to be measured between appropriately matched habitats upstream and downstream of discharges to water or, where there is no suitable
upstream site, between reference condition and downstream site.

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APPENDIX 2. OBJECTIVE F.1.2 POLICY D.4.1

Objective F.1.2 Water quality
Manage the use of land and discharges of contaminants to land and water so that:
1)
existing water quality is at least maintained, and improved where it has been degraded below the river, lake or coastal water quality
standards set out in H.3 Water quality standards and guidelines, and
2)
the sedimentation of continually or intermittently flowing rivers, lakes and coastal water is minimised, and
3)
the life-supporting capacity, ecosystem processes and indigenous species, including their associated ecosystems, of fresh and coastal
water are safeguarded, and the health of freshwater ecosystems is maintained, and
4)
the health of people and communities, as affected by contact with fresh and coastal water, is safeguarded, and
5)
the health and safety of people and communities, as affected by discharges of sewage from vessels, is safeguarded, and
6)
the quality of potable drinking water sources, including aquifers used for potable supplies, is protected, and
7)
the significant values of outstanding freshwater bodies and natural wetlands are protected, and
8)
kai is safe to harvest and eat, and recreational, amenity and other social and cultural values are provided for.
Note:
Freshwater quality objectives required by Policy A1 of the National Policy Statement for Freshwater Management 2017 will be included in this
Plan at a later date as per the Council's programme for implementing the National Policy Statement.

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Policy D.4.1 Maintaining water quality (wording agreed between NRC/MOC/RFPBS)

When considering an application for a resource consent to discharge a contaminant into water or onto or into land where it may enter water:
1)
Where a water quality standard in Appendix H.3 is currently met, resource consent will only be granted if the discharge will not cause the
quality of water in a river, lake or the coastal marine area to no longer meet a standard in Appendix H.3;
2)
Where a water quality standard in Appendix H.3 is not currently met, resource consent will not be granted for a new discharge if the
discharge will, or is likely to, cause or contribute to a further exceedance of a water quality standard in Appendix H.3;
3)
Where a water quality standard in Appendix H.3 is not currently met and the exceedance of the water quality standard is caused or
contributed to by an existing activity for which a replacement resource consent is being considered, any replacement resource consent
granted for the existing discharge must include a condition(s) that requires the quality of the discharge to be improved over time to
reduce the contribution of the discharge to the exceedance of the water quality standard in Appendix H.3;
4)
Ensure that the discharge will not cause an acute toxic adverse effect within the zone of reasonable mixing;
5)
Where a discharge will or is likely to cause or contribute to an exceedance of the coastal sediment quality guidelines in Appendix H.3.4
determine whether higher levels of contaminants in the particular location affected by the discharge can be provided for while still
achieving Objective F.1.2, and set appropriate levels of contaminants in accordance with best practice methodology to safeguard the
ecosystem values present at the location affected by the discharge; and
6)
Where existing water quality is unknown, or the effect of a discharge on water quality is unknown, the activity must be managed using a
precautionary approach, which may include adaptive management.
Note:
For the purpose of Policy D.4.1(5), best practice methodology can be determined by reference to ANZECC 2000 Australian and New
Zealand Guidelines for Fresh and Marine Water Quality, Number 4, Volume 1 or any replacement guidelines.