Freshwater Toxic Algae Monitoring

Use the tabs below to see toxic algae cover at Tier 1 and Tier 2 sentinel sites in respective Whaitua for the 2018/19 summer season. The black line shows river flow and the asterisks indicate presence of detached toxic algae mats. The yellow and red dotted lines mark alert and action levels of toxic algae cover respectively.

Te Whanganui-a-Tara

Toxic algae levels remained below guideline levels (<20%) for the 2018/19 summer season at all routinely monitored (Tier 1 and 2) sites. However, exceedances (>20%) were observed in areas outside of the routinely monitored network at Pakuratahi River at the Kaitoke Campsite and the Waipapa Stream on the South Coast.

Tier 1 Sites

Tier 2 Sites

Ruamahanga

Toxic algae remained below guideline levels (<20%) for the 2018/19 summer season at all routinely monitored sites, with the exception of Waingawa River at South Road and Ruamahanga at Double Bridges. Detached mats were observed on four occasions at the Waingawa River site following an almost month-long period without rain and correspondingly low river flows.

Tier 1 Sites

Tier 2 Sites

Kāpiti Coast

Below average rainfall and longer than usual accrual periods in the Kāpiti Whaitua led to the first toxic algae blooms in the last ten years in the Otāki and Waikanae Rivers. Otāki River at Hautere Water Treatment Plant (included as a surrogate site for Otāki River at State Highway One due to access issues at SH1), reached alert guideline levels on two occasions in February, reaching a maximum of 24% toxic algae coverage.