STATEMENT OF PRIMARY EVIDENCE OF Richard Goodwin Storey ON BEHALF OF WELLINGTON REGIONAL COUNCIL

Evidence for these matters: Assessment of the relationship between dissolved nutrients and MCI values in Wellington streams and rivers. and setting region-wide nutrient limits as a means for meeting target MCI values in Wellington streams and rivers.

Scope of evidence Assessment of submissions relating to nutrient management for achieving target MCI values in Wellington streams and rivers Alternative methods for achieving target MCI values

Issues raised in the evidence of Dr. Russell Death Validity of the correlations between MCI and nutrients in datasets containing modelled data only. The strength of correlations using measured values of MCI and nutrients. Lack of consideration of other factors likely to influence MCI values in addition to nutrients, particularly in urban catchments. Lack of consideration of the pathway by which nutrients may affect MCI, and what other factors may influence this pathway. Appropriateness of nitrate and dissolved reactive phosphorus as the most relevant measures of available nitrogen and phosphorus, respectively Applying a single relationship between MCI and dissolved nutrients to all stream types in the region. The implied assumption that MCI will improve when a stressor is reduced.

Accident rate Colour of car Average age of driver Colour of car 60 40 20 40 60 Colour of car

Issues raised in the evidence of Dr. Russell Death Validity of the correlations between MCI and nutrients in datasets containing modelled data only. The strength of correlations using measured values of MCI and nutrients. Lack of consideration of other factors likely to influence MCI values in addition to nutrients, particularly in urban catchments. Lack of consideration of the pathway by which nutrients may affect MCI, and what other factors may influence this pathway. Appropriateness of nitrate and dissolved reactive phosphorus as the most relevant measures of available nitrogen and phosphorus, respectively Applying a single relationship between MCI and dissolved nutrients to all stream types in the region. The implied assumption that MCI will improve when a stressor is reduced.

From Matheson et al. (2015)

From Matheson et al. (2015)

Source: Clapcott et al. (2011) Sediment Assessment Methods

Max annual periphyton cover in Ruamahanga SoE sites

Issues raised in the evidence of Dr. Russell Death Validity of the correlations between MCI and nutrients in datasets containing modelled data only. The strength of correlations using measured values of MCI and nutrients. Lack of consideration of other factors likely to influence MCI values in addition to nutrients, particularly in urban catchments. Lack of consideration of the pathway by which nutrients may affect MCI, and what other factors may influence this pathway. Appropriateness of nitrate and dissolved reactive phosphorus as the most relevant measures of available nitrogen and phosphorus, respectively Applying a single relationship between MCI and dissolved nutrients to all stream types in the region. The implied assumption that MCI will improve when a stressor is reduced.

Scope of evidence Assessment of submissions relating to nutrient management for achieving target MCI values in Wellington streams and rivers Alternative methods for achieving target MCI values