Water and soil monitoring trends causes concern
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Water and soil quality monitoring trends cause for concern
For immediate release: 18 December 2009
Latest water and soil quality monitoring trends are giving Environment Bay of Plenty councillors and staff major cause for concern.
Regulation Monitoring Operations Committee Chairman Malcolm Whitaker is urging his fellow councillors to consider the impacts of increased nutrient leaching from soil and its impacts on water quality over time as they develop the next Regional Policy Statement.
“The nutrient levels in soils aren’t so high at the moment that they’re causing major problems but the increasing trends will be significant over time, and that is of concern and something we need to be factoring into our planning for the region,” Councillor Whitaker said.
“The impetus is on us to ensure the quality of water is maintained and not degraded over time through land use.”
Latest monitoring of dairy pasture and maize cropping sites throughout the region showed an increase in the levels of anaerobically mineralisable nitrogen and phosphorus in dairy sites, which could potentially lead to increased pollution of our water bodies.
Environment Bay of Plenty Group Manager Water Management Eddie Grogan said the factors causing the increasing trends are inextricably linked.
“What goes onto the land ends up in our groundwater systems, the shallower or more porous the aquifers are the more likely it is that the groundwater will be high in nutrients, leading to contamination of our lakes, rivers and streams,” Mr Grogan said.
“Excess nutrients on the land end up in our groundwater systems, and while the deeper aquifer systems where we get our drinking water from are well within the Ministry of Health’s acceptable limits for nitrate-nitrogen levels, we cannot be complacent. Monitoring showed high levels of nitrate-nitrogen in shallower bores and near surface bores, which is a direct link to land use, in particular dairying, horticulture, agriculture and pastoral use,” Mr Grogan said.
He said shallower groundwater with high nitrate-nitrogen levels was more likely to pollute nearby waterways – something the region can ill afford.
“Yet another disturbing trend from the latest monitoring is that at the same time the water quality of many of our rivers and streams is deteriorating. The main indicators of this are increases in nitrogen, bacteria and suspended solids/turbidity – once again, notably in catchments dominated by pastoral agriculture and horticulture,” Mr Grogan said.
Of the 40 rivers and stream sites monitored, 12 sites showed significant increases in nitrogen and 15 sites showed significant increases for the indicator bacteria Escherichia coli (E-coli), which indicates faecal contamination and an increased risk to people using waterways for recreation or water supply.
Increasing turbidity (water cloudiness) was also found in a range of Bay of Plenty rivers and streams.