Increasing levels of agricultural pollutants in the water and soil are concerning Environment BOP councillors and staff.
The latest monitoring of dairy pasture and maize cropping sites throughout the region show increases in the levels of anaerobically mineralisable nitrogen and phosphorus in dairy sites.
The increased mineralisation can lead to increased pollution of lakes and rivers.

Water quality of streams and aquifers is deteriorating

'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,” says Regulation Monitoring Operations Committee Chairman Malcolm Whitaker.
EBOP water management group manager Eddie Grogan says factors causing the increasing trends are linked.
'What goes onto the land ends up in our groundwater systems,” says Eddie. 'The shallower or more porous the aquifers are, the more likely it is the groundwater will be high in nutrients, leading to contamination of lakes, rivers and streams.”
EBOP's 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.
Shallower groundwater with high nitrate-nitrogen levels is more likely to pollute nearby waterways – something the region can ill afford.
'Another disturbing trend from the latest monitoring is that the water quality of many of our rivers and streams is deteriorating at the same time,” says Eddie. 'The main indicators are increases in nitrogen, bacteria and suspended solids/turbidity – once again, in catchments dominated by pastoral agriculture and horticulture,” says Eddie.
Excess nutrients on farmland end up in groundwater systems, says Malcolm. The deeper aquifer systems that provide drinking water are still well within the Ministry of Health's acceptable limits for nitrate-nitrogen levels.
'We cannot be complacent,” says Malcolm.
Of 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 - 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.