MOF, Alm.del - 2023-24 - Bilag 79: Evalueringsrapporten af Second Opinion fase II

Miljø- og Fødevareudvalget 2023-24
MOF Alm.del Bilag 79
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Annex 1. Replies from the Panel to selected stakeholder comments that was received in the

hearing process of the first draft of the international evaluation report

Content

Replies to Danish Agriculture and Food Council (Landbrug & Fødevarer)

– pp. 2-3

Replies to The Danish society for Nature Conservation (Danmarks Naturfredningsforening)

– pp. 3-4

Replies to Bæredygtigt Landbrug

– p.4

Replies to Green Transition Denmark (Rådet for Grøn Omstilling)

– p.5

Replies to SEGES Innovation

– pp. 5-8

Replies to Limfjordsrådet

– p.8

Replies to Ocean Institute (Tænketanken Hav)

– p.8

Replies to Danish Sports Fishing Association (Danmarks Sportsfiskerforbund)

– p.8

Replies to Fair Spildevand

– p.9

10.

Replies to University of Aarhus: Danish Centre for Environment and Energy

– p.10

11.

Replies to DHI, DTU, AU: Coastal modelling group

– p.10

Page numbers above refer to the page numbers in Annex 1 where the organisations’ comments are addressed.

Page number within the Table of replies in Annex 1 refer to the pages in Annex 2 where the stakeholder’s original and full comments can be found.

MOF, Alm.del - 2023-24 - Bilag 79: Evalueringsrapporten af Second Opinion fase II

SELECTED COMMENTS FROM THE

STAKEHOLDERS

(page no. refer to Annex 2)

REPLIES BY THE INTERNATIONAL PANEL

SECTIONS

MODIFIED

Danish Agriculture and Food Council (DAFC) (Landbrug & Fødevarer)

Ch. 1 (A) How can strong changes between

RBMP2 and RBMP3 be reconciled with small

uncertainty reported in RBMP2 – p.2

Ch.1 (B). Have reference values been updated

after the discovery of an analytical error – p.2

Ch.1 (C). does adjustment of G/M boundary to

intercalibration lead to adjustments for inner

waters, otherwise EQR would differ – p.2

Ch.2 (A). why are responses of Chl-a and Kd to

nutrients "reasonably accurate", and what does

that mean exactly? – p.3

Ch.2 (B). how to reconcile large changes

between RBMP2 and RBMP3 with low levels of

reported uncertainty – p.3

The uncertainty reported was the uncertainty on the models and a fair estimate. It did not account for

additional uncertainty stemming from lumping water bodies in too crude classes. It is not clear how

well this was communicated, but it does not have strong consequences for RBMP3

The Panel has investigated this. Reference conditions have not been recalculated. The way this was

treated has been added to the report in section 1.4.6, including the Panel's assessment of the

process

There is no scientific reason to adjust G/M boundaries for inner waters, as these were not affected by

the boundary and initial conditions in the Baltic that influenced the reference values in open waters.

EQRs can be water type specific and need not be the same across all water bodies. This is now

explained in the text.

As explained in the text, it can be expected that Chl-a and Kd have short-term variability that is not

perfectly modelled. The Panel has asked and received comparisons at seasonal scale, which were in

general satisfactory. In particular, as stressed in the report, the ability of the models to predict the

level of eutrophication correctly in very diverse water bodies with very different levels of nutrien input,

was quite impressive

The overall uncertainty in RBMP2 on MAI, was mostly caused by the type classification rather than

the intrinsic model uncertainty. The crude classification was - correctly - pointed out by stakeholders

as a weakness of the approach, and changes to this aspect were requested by the 2017 International

Panel. This request was granted, thanks to large efforts of researchers and Ministries. The Panel

assesses these changes as a significant improvement. It is impossible to achieve a significant

improvement without changing things. Stakeholders who requested such improvements should not

complain that they change things, as long as the changes are for the better.

Definitely yes, as stated in the report

In RBMP3, where most variables are water body specific, the difference should be small

A section 1.4.8 has been added to the report, detailing the Panel's position

It was outside the Panel's scope and abilities to check all calculations on all water bodies. A general

remark on errors and how to cope with them, if unfortunately they occur, has been added to the text.

The Panel is delighted to read this confirmation of shared concern. As for wetlands and similar

approaches, more emphasis has been added to the report in chapter 5 (seasonality) and chapter 3.

Such map does exist. It was not incorporated into the Panel's report because it did not serve a

particular purpose in the report. Danish water bodies have different degrees of ‘openness’, in the

sense that they are to a varying degree influenced by Baltic water and by nutrient contributions from

these waters. The Panel has used the term ‘open waters’ in a relative sense. To the degree that

none

section 1.4.6

(new section)

section 1.4.5

(end of

section)

none

Ch.2 (B). Are uncertainties estimated better this

time? – p.3

Ch.2 (B). Are uncertainties higher at water body

level than at model level? p.3

Ch.2 (C). Does the Panel still agree with

downweighing Kd as suggested in 2017? - p.3

Ch.3 (A). Errors in the status load calculation

for two water bodies – p.3/4

Ch.3 (B). Time has been lost. Emphasis on

wetlands and landscape changes – p.4

Ch.4 (A). Is there a map of contribution of

neighbouring countries to the load in all water

bodies? – p.4

none

section 1.4.8

(new section)

section 3.4.1

section 3.4.3 /

section 5.4.3

section 4.3

section 1.4.3

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SELECTED COMMENTS FROM THE

STAKEHOLDERS

(page no. refer to Annex 2)

REPLIES BY THE INTERNATIONAL PANEL

semi-open fjords are also influenced by Baltic waters, statements on ‘open waters’ also apply at least

partly to these water bodies. Minor change to clarify that has been added to Ch.4 and Ch.1.

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MODIFIED

Ch.4 (B). Is it irrelevant to discuss possible

future changes to WFD – p.5

Ch.5. Does the Panel agree that stormwater

overflows should be monitored and reported

more intensively – p.5

Ch.6. Reiterating points from SEGES – p.5/6

Ch.7 (A). Should other stressors not be

addressed at the same time – p.6

Ch.7 (B). Should some restoration measures

(e.g. sand capping) be taken immediately to

fasten ecosystem response? – p.6

The Panel still advises based on existing, rather than possible or expected law. Text is clarified on

this subject

The section on stormwater overflows in Ch.5 has been extended and amended to better express the

Panel's view

We refer to the reply to SEGES' remarks

The Panel has extended and clarified the text in Ch.7 to better discuss this point of sequence versus

simultaneous treatment.

Sand capping is an expensive method, both in monetary value and energy expenditure, and will likely

be restricted to small local interventions. The same applies to mussel culture, which in addition

should be carefully studied because of the danger of accumulation of (pseudo)faeces on the

sediment with ensuing high oxygen demand and potential P release. In general, the Panel warns

against using these measures to hide symptoms before the underlying eutrophication problems are

solved. Having said that, there is no reason not to consider how these approaches could be used for

enhanced ecosystem restoration once conditions are sufficiently improved.

The Panel has explicitly stated that reduction of some other stressors may be needed in addition to

effective measures for nutrient reduction. The Panel has no opinion about removal of stone reefs.

section 4.4.3

section 5.4.2

none

section 7.4.3

no change in

Ch. 7 but see

section 3.4.3

Ch.7 (C). Are restoration measures needed

because N reduction alone will not suffice? –

p.6

none

The Danish society for Nature Conservation (Danmarks Naturfredningsforening)

Ch.3. DN cannot share the Panels optimism for

the RBMP3 – p.8

Ch.3. Flaws in models of N-leaching? – p.8

Ch.8. No deterioration demand in the Water

Framework Directive as well as other directive

obligations. p.9/10

Ch. 8. Fitness check reference – p.10

Ch.8 (and ch.3) Claim that the overall trend for

the state of coastal waters has moved from

moderate towards bad during the last RBMP

The Panel agrees on the essentials, but reserves the right to be more optimistic than the stakeholder

none

(but see

extended

section 3.4.3)

none

section 8.2.1

Section 8.2.2

Section 8.5.4

The Panel has not analysed the models for N-leaching from the fields in detail. However, in general

terms the need for more data and knowledge on the effectiveness of measures has received high

emphasis in the Panel's report

Text inserted to explain the non-deterioration objective.

Reference inserted and the argument adjusted to some extent.

We have explained in chapter 8 the interrelation between the question raised and the use of

exemptions

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SELECTED COMMENTS FROM THE

STAKEHOLDERS

(page no. refer to Annex 2)

period, and that should be taken into account in

considering exemptions – p.10

Ch.9. General remarks on the conclusions –

p.10

REPLIES BY THE INTERNATIONAL PANEL

SECTIONS

MODIFIED

The Panel assesses this section as a concise statement of DN's position in the societal debate, to

which it does not need to comment

none

Bæredygtigt Landbrug

Not all conclusions from sections in chapter

conclusions. Example section 2.4.4 – p.12

Ch.1. Year 1900 discussion – p.12

Ch. 1-2. Eelgrass. Importance of wasting

disease. Need for restoration – p.12/13

Ch. 5. Seasonality – p.13

True. Chapter conclusions extended to cover this section

Section rewritten to clarify the Panel's position

Panel is aware of the wasting disease but does not think this influences the current discussion much.

Position on time sequence for measures against 'other pressures' clarified in Ch. 7

Panel has clarified its view on measures targeting summer loads especially. Few technical measures

are available, but the discussion now includes wetlands as promising initiatives. Some accounting

favouring N retention in summer is advocated

Panel has made some additional remarks on stormwater overflow measures

The Panel has not studied the relative role of point versus diffuse sources in every individual water

body. Conclusions depend on what has been reported in the studies that were available to the Panel.

Note that more detailed results may become available in Phase III of the project

The Panel has not reviewed any studies or models distinguishing the role of complex bound

phosphorus from brink erosion.

The Panel cannot follow the discussion of figs 6.1-6.3 in this contribution. DIP in summer is shown to

be very high due to release from the sediment, and is thus very far from being limiting (DIP is the

second figure)

Without context, this quote is difficult to react to

The Panel has not made an economic assessment of possible measures, as the emphasis of its task

was on evaluating the marine models. In Chapter 8, the importance of social and economic

assessment in relation to exemptions is discussed

section 2.5

section 1.4.7

section 7.4.3

sections

5.4.3, 5.4.4

and 5.5

section 5.4.2

none

Ch. 6. Measures to limit stormwater overflow –

p.14

Ch. 6. Diffuse source vs. point source measures

– p.14

Ch. 6. Phosphorus - relative role of

orthophosphate and complex bound phosphate

– p.14

Ch. 6. Discussion of figures 6.1-6.3 – p.15

Quote from Prof. Timmerman – p.15

Economic assessment – p.15

none

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SELECTED COMMENTS FROM THE

STAKEHOLDERS

(page no. refer to Annex 2)

REPLIES BY THE INTERNATIONAL PANEL

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Green Transition Denmark (Rådet for Grøn Omstilling)

Ch.1-2. G/M target setting: only 50 per cent

chance of reaching GES. – p.16

It is our conclusion that using the averaging approach instead of one-out-all-out or other stricter

approaches when evaluating need for nitrogen reduction is justified at this stage, given the

uncertainties in the calculations. We totally agree that the goal is GES according to evaluation of the

actual state in the coastal waters. The measures are a means towards this goal and not a goal in

themselves. Increased precision in calculations of needed reductions and efficiency of measures

probably will be needed in forthcoming RBMPs, hence the importance attached to proper monitoring

of results of measures.

Our intention was not to play down the major problems associated with the excess phosphorus that

is typical for regions with intensive animal husbandry. We have noted large quantities of manure still

spread on the soils of Jutland. Thus, we agree that there are many reasons to increase phosphorus

recycling and curb losses. Our discussion in Chapter 6 has primarily focused on the current problems

in the coastal water bodies where we observe that the acute problem primarily is the extremely high

nitrogen concentrations, but that also some credit can be accounted for when phosphorus losses are

minimized. We have added a few considerations on phosphorus measures in chapter 5 and 6.

This point has been made in Ch.7. Text has been expanded compared to draft version. Note,

however, that we warn against starting restoration efforts before basic water quality is sufficiently

restored.

It is a matter of public societal debate what measures will be sufficient and proportionate. We have

extended the text on existing measures and their effects in Ch. 3, and we have inserted some text in

the relation between RBMP and the use of exemptions in Ch. 8.

none

Ch. 6. Phosphorus efforts matter and are

important to implement now. Also in agriculture

(examples given) – p.17/18

section 5.4.3

section 6.4.1

Ch. 7. Also important to act now on some other

stressors: Essential to stop bottom trawling in

areas where eelgrass must recover. Eelgrass

recovery is in some areas a Sisyphean task if

we continue bottom trawling – p.18

Ch. 8 (and Ch.3). Existing measures

insufficient: the voluntary schemes (kollektive

virkemidler) - i.e. wetting of land and

afforestation – introduced in recent Danish

RBMPs will not have sufficient effect – p.18/19

section 3.4.3

section 7.4.3

section 3.4.3

section 8.5.4

SEGES Innovation

Small catchments at N Sea coast – p.20

Ch.1-2. Eelgrass depth limit as indicator for

angiosperms in shallow water bodies: G/M

boundary is not truncated to water body

maximum depth in either assessment or models

– p.20/21

Ch.1. Is eelgrass depth limit (and not eelgrass

cover) sufficient as indicator for WFD – p.21

It was outside the Panel's scope and abilities to check all calculations on all water bodies. A general

remark on how to handle these cases has been added to Ch. 3

The Panel agrees with the observation that it is inconsistent not to use Kd's corresponding to

truncated eelgrass depth limit G/M boundaries in shallow water bodies. In our assessment it will

change N-MAIs only in very few water bodies. A new section of text has been added on this problem.

The true indicator is rooted angiosperm depth limit, and this has been formally accepted by the

European Commission. This has been added to the text in Ch.1.

section 3.4.1

section 2.4.3

(and related

change in

section 2.5)

section 1.4.8

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SELECTED COMMENTS FROM THE

STAKEHOLDERS

(page no. refer to Annex 2)

Section 1.4.4 validity of new reference

conditions – p.21

REPLIES BY THE INTERNATIONAL PANEL

The time lag in P load of the Baltic, although very relevant for current-day measures and for

evaluating the realism of G/M boundary values, is not relevant for calculating reference conditions.

Neither are the interests of Danish farmers, as there are no modern Danish farmers in the reference

conditions. This, of course, does not dismiss the present-day importance of the interests of farmers in

any sense!

This section in the report has been rewritten to clarify the Panel's position.

The Panel has commented on that approach in a response to COWI/NIRAS. The Panel is not in

favour of using a double-step regression approach, as it amplifies uncertainty compared to the direct

relations between load and indicators.

Our trust in that the dynamic mechanistic models provides reasonably accurate responses to nutrient

input change is not only based on the comparison to observations, but also on an assessment of the

model formulations and parametrizations. The model formulations of the DHI model system are not

unique, but based on long-term development and knowledge within the international scientific

community and used in models world-wide.

We have not investigated how large deviations there are in the calibration parameters between the

model implementations. However, it should be noted that there is only one set of calibrated

parameters for each model implementation, which means that, for example, all water bodies in

Limfjorden are modelled with exactly the same model and parameters. Hence, there is no separate

calibration between the Skive Fjord and Hjarbæk Fjord, and with the same set of parameters the

model is capable of simulating nutrient concentrations and Chl-a/kD across a rather wide range of

eutrophication states throughout Limfjorden. The latter lends some credibility to that calibration is

rather good and nutrient levels and Chl-a/kD should respond relatively accurate to nutrient supply

change.

It is quite difficult for us to evaluate single fjord peculiarities, because a detailed knowledge about the

local dynamics is necessary to make a proper assessment on what is exactly going right or wrong.

For Hjarbæk Fjord, it is indeed a correct observation that oxygen concentrations in the deep is

frequently overestimated ‒ in particular during early summer. However, we also notice in the

observations that low O

concentrations are interrupted by higher values (more similar to modelled

concentrations) which leads to the speculation that intrusions of dense water with higher oxygen

concentrations occur during the summer season. Lack of oxygen depletion would eliminate the part

of phosphate release associated with iron-oxide particles reduction and potentially make less P

available during late summer. However, the comparison between modelled and observed phosphate

concentrations does not show a consistent underestimation in the model results. But if phosphate is

too low, nitrogen limitation may be overestimated in this fjord by the model, which in principle should

result in an overestimated N-MAI. The long-term data indicates that winter concentrations of both

nitrogen and phosphorus decreased quite much since the 1980s and that the fjord transited from

hypertrophic to P-limitation in spring and N-limitation in summer in the last decade.

Concerning Mariager Fjord, we agree that it is difficult to see the summer nutrient concentrations in

the graphs at the DHI web-site and it is easily missed that N-limitation does not occur (also missed in

Gertz et al., 2022,

Nutrient limitation in Danish Coastal Waters

where summer nitrogen limitation is

indicated). We agree that Mariager Fjord is in a hypertrophic state from mid-summer and primary

SECTIONS

MODIFIED

none

Ch.1. Year 1900 discussion – p.21

Ch.1 Other method for estimating Chl-a

reference. = double regression – p.22

Ch. 2. In 3 of 4 examples investigated by

SEGES, the MECH-models do not explain the

ecological situation/response very well –

p.22/23

section 1.4.7

none

section 2.4.2

(minor

changes)

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SELECTED COMMENTS FROM THE

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(page no. refer to Annex 2)

REPLIES BY THE INTERNATIONAL PANEL

production is limited by some other factor than nutrient availability. The model results are N-limited

(or some years co-limited by N and P), so the factor causing hypertrophy is apparently not captured.

The implication from this is that the modelled sensitivity of e.g. Chl-a to N- and/or P-load reductions

could be overestimated, but it does not mean that the system will not reach nutrient limitation when

concentrations decrease (as for example for Hjarbæk Fjord discussed above). Given that need for

reduction of nitrogen (NFR) already is about 58 per cent compared to baseline, we do not think the

stronger sensitivity to N-reduction (and potential overestimate of N-MAI) is a major issue.

Ringkøbing Fjord is indeed an interesting case of top-down control of the phytoplankton biomass and

illustrates nicely the limitations of Chl-a as sole indicator of eutrophication in some cases. It is difficult

for us to assess how DHI calibrated the model to reproduce both nutrients and, at least summer, Chl-

a reasonably well, but a guess could be that the effect of benthic filtration feeders were replaced by

zooplankton grazing. It may well be that more refined work is needed to validate the NFR for this

area. Nevertheless, it is clear that the nutrient status of Ringkøbing Fjord has not changed by the

introduction of benthic filtration feeders and the system remains in a highly eutrophic state and any

disturbance to the benthic community will result in return of massive blooms. In summary, the cases

discussed by SEGES show some deviations between model and observations, but none of these

deviations would lead to large deviations in the calculated N-MAIs. We therefore maintain our

appreciation that the models are fit for purpose.

The surrogate model uses the sensitivities computed with the models, so in that respect it includes all

processes and dynamics included the MECH and STAT models themselves. What can be critical,

and is discussed to some extent in the report, are cases far from the G/M boundary where the

sensitivity of Chl-a/kD to load change may be underestimated using the 30% load reduction

scenarios. Further, we propose that some of the assumptions made could be validated by examining

a mechanistic simulation using the final MAIs/NFRs.

The panel agrees that when using the 3-year average the sensitivity of the status load to abnormal

years are higher than the piece-wise regression approach. However, for both methods, the

uncertainty of the estimate is easily quantifiable.

this time lag is well known to the Panel. In fact, one Panel member has strongly contributed to the

estimation of this time scale. The Panel reminds that exactly this type of phenomena is meant when

discussing 'natural conditions' preventing the rapid return to target conditions, in Ch. 8 of the report.

We feel that we have thoroughly taken this into account.

Part of this section has been rewritten. SEGES has misinterpreted the position of the Panel, where it

is stated that it is difficult to find measures that reduce N

only

in summer. The possible use of

wetlands as 'seasonal' measures has now received more attention, as the Panel felt that the

possibilities offered by wetland construction were insufficiently stressed in the draft version. In the

rewritten text, the Panel advises more clearly on how seasonally variable measures such as wetlands

can be reconciled with year-round reduction targets

Reference was made to coastal waters, where this is the case. The point has been rephrased (in Ch.

6) to avoid controversy

SECTIONS

MODIFIED

Ch.2. Surrogate model removes important

information from complex ecosystems and with

that a high risk of not including important

processes. For example, this method will

exclude proper use of seasonality. – p.23

Ch.3. Status load, 3-year methodology – p.23

Ch.4. Time lag of P in Baltic (agriculture is

paying for that in the N-MAIs) – p.23

Ch.5. Seasonality discussion – p.23

none

None (but text

clarified a bit

in section 3.1)

none

section 5.4.3

(and related

changes in

5.4.4 and 5.5)

section 6.4.2

Ch.5. No basis for arguing that N loads will ever

be so low as to give spring limitation – p.24

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SELECTED COMMENTS FROM THE

STAKEHOLDERS

(page no. refer to Annex 2)

Ch.5. Possibilities to do something with

seasonality, e.g. using wetlands, drainage etc..

– p..24

Ch.6. Strategy of reducing N and P

simultaneously – p.24

REPLIES BY THE INTERNATIONAL PANEL

The Panel is sceptical of measures involving management of drainage, as already expressed in the

draft text. However, possibilities involving wetlands, although not truly 'seasonal measures' have now

been better emphasized in Ch. 5

Our intention was not to play down the major problems associated with the excess phosphorus that

is typical for regions with intensive animal husbandry and we have noted large quantities of manure

still spread on the soils of Jutland. Thus, we agree that there are many reasons to increase

phosphorus recycling and curb losses. Our discussion in Chapter 6 has primarily focused on the

current problems in the coastal water bodies where we observe that the acute problem primarily is

the extremely high nitrogen concentrations, but that also some credit can be accounted for when

phosphorus losses are minimized. We have added a few considerations on phosphorus measures in

chapter 5 and 6.

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MODIFIED

section 5.4.3

section 6.4.1

Limfjordsrådet

Ch. 5,6,7. The importance of local initiatives

and engagement in elaborating the local causes

of pollution and devising solutions – p.26

The Panel thanks the Limfjord Council for its positive and future-oriented approach and its careful

consideration of feasible solutions. The report has been amended in chapters 5 and 6 to highlight the

Panel's position on providing both strong guidance and openness to local initiatives

section 6.4.1

section 5.4.3

section 5.4.4

Ocean Institute (Tænketanken Hav)

Ch. 7. Too formal approach to other stressors –

p.27

Ch. 8: Position of Ocean Institute on

exemptions – p.28

By mentioning which stressors are primarily regulated by which directives, the Panel did not want to

dismiss them as irrelevant to the present discussion. However, a formal approach can be useful in

determining how to tackle the different stressors. Text has been amended to make this clearer

The Panel has restricted itself to sketching the legal options. Whether these should be taken, is the

subject of political debate, in which Ocean Institute has taken position

section 3.4.3

section 7.3

section 7.4.1

none

Danish Sports Fishing Association (Danmarks Sportsfiskerforbund)

Ch. 6 DSFA does not believe there is scope for

progress in N/P combined measures – p.31

Ch. 8. DSFA does not see room for exemptions,

based on poor performance in RBMP1 and

RBMP2 – p.33

This interpretation differs from the Panel's position

This is DSFA's position in the societal debate, to which the Panel does not comment. We have

inserted text on the relation between RBMP and the use of exemptions in chapter 8.

none

section 8.5.4

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none

Fair Spildevand

Total comment p.34/38

The Panel strongly disagrees with the claims that there is no scientific evidence that curbing nutrient

inputs to Danish coastal waters leads to improved water quality. Actually, the sensitivity studies of the

scientifically well-founded models used in preparation of the RBMP is one of these proofs in itself.

The Panel has considerable difficulty following the unstructured reasoning in the comments.

However, the Panel identified a clear misconception in that the regulation of inorganic nutrient

concentrations in the world ocean, as pioneered by Redfield (1933), can be transferred to coastal

systems. The global ocean balance evolves in deep ocean on timescales of the order of 1000s of

years, while the shallow Danish coastal systems have short residences times, are regulated by other

processes, such as benthic-pelagic interaction, and strongly forced by external drivers. One common

factor, though, is that also in the coastal systems, plankton uptake is of the order of Redfield ratio.

There is no contradiction between Redfield’s observations of the composition of inorganic nutrients in

the world ocean and Liebig’s law. The Panel has the impression that, with Liebig’s law, the

stakeholder rejects the entire concept of nutrient limitation of phytoplankton. That is impossible and

contradictory to Redfield theory, as it would lead to the absurd conclusion that phytoplankton grow at

full speed and incorporate nitrogen in 7:1 proportion to phosphorus, even in conditions where no

nitrogen at all would be available for uptake.

The Panel has the impression that Fair Spildevand claims that nutrient concentrations in Danish

waters are not monitored or taken into account when constructing the models. That is not true.

Extensive datasets from monitoring have been collected over many years and are publicly available.

They played a crucial role in calibrating and validating the models used in RBMP2 and RBMP3.

Fair Spildevand seems to suggest that low nitrate concentrations in summer are a clear indicator that

waters do not suffer eutrophication. However, these concentrations are low because nutrients are

taken up by large populations of phytoplankton. The build-up of organic matter subsequently causes

strong oxygen demand when phytoplankton decomposes. There is ample evidence that heavy

eutrophication and severe water quality problems can go hand in hand with low summer nitrate

concentrations. Using winter concentrations as a measure of what will be taken up and incorporated

in organic matter during the coming growing season is a much more useful first-order approach.

Fair Spildevand is entirely correct when stating that nutrient loads must be scaled to the size, flushing

regime and other characteristics of a water body. It makes a difference if one adds a ton of nitrogen

to a bathtub or to an ocean. The Panel assures the stakeholder that this obvious relation is carefully

taken into account in the models and that this is not a cause for concern.

In summary, the Panel sees no merit in Fair Spildevand’s attempt at overthrowing the fundamental

principles of nutrient regulation in coastal waters. There is ample evidence that it makes perfect

sense to regulate and reduce the nutrient load from diffuse and point sources, including the N-load,

to restore the ecological balance in coastal and inner water bodies.

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REPLIES BY THE INTERNATIONAL PANEL

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University of Aarhus: Danish Centre for Environment and Energy

Ch.3. Reference to N-model referred to in the

text? – p.39

new sources of bias in the data – p.39

Research topics proposed by DCE – p.39

It is clarified in the text

The panel has added a section in Ch.1 on the necessity to build scientific consensus on data bases

before

extensive model calculations are performed

These topics are - at slightly more general level - already covered in the Panel's recommendations

section 3.4.2

section 1.4.6

none

DTU, DHI, AU: Coastal modelling group

Mention historical basis for reference

conditions, following CIS guidance #5 – p.40

Suggestion to revise the intercalibration with

Sweden/ criticism of guidance #30 – p.40

Added to the text

The Panel differs of opinion with the researchers on this point. The Panel's position is clarified in

section 1.5 (conclusions and recommendations)

section 1.1

section 1.5