Taupō wastewater and sewage discharge
About 2pm on Tuesday (2 July 2019), a water main break caused a large washout on the lakefront in Taupō. About an hour later the footpath collapsed and took out a wastewater pipe causing wastewater to enter the lake. Taupō District Council successfully diverted waste back into their treatment station.
Below is information from Waikato Regional Council on our response to the Taupō wastewater and sewage discharge.
Current at 0930h: Wednesday 24 July 2019
Water quality: Waikato River
- Levels of E.coli in the Waikato River to Ohaaki Bridge have been consistently ‘safe’, making them within the guidelines for recreational contact. The one exception was from a sample collected at Cherry Island within a day of the initial sewage discharge on 2 July.
Water quality: Lake Taupō
- We have collected water samples from 13 near-shore sites in Lake Taupō. Not unexpectedly, levels of E.coli in Lake Taupō were extremely high at the mixing point of the discharge immediately following the incident, but decreased markedly. By day 11 – 12 July – E.coli levels in water samples collected were all ‘safe’, meaning they were below the guidelines for recreational contact.
- As a result of a second wastewater discharge incident at the Lake Terrace site on 16 July, we carried out further sampling. Again, not unexpectedly, the results of four water samples we collected from Lake Taupō showed very high concentrations of E.coli.
NIWA has analysed the macroinvertebrate samples collected by the regional council. From our first glance at these results there is no indication of any adverse effects on lake bed life. Indeed, there appears to be higher numbers of invertebrates at the site immediately below the discharge. This could be associated with the input of organic material providing a food source.
Lakebed sediment sampling
Sediment sampling was also carried out at five lakebed sites on the Lake Taupō foreshore on 10 July. While E.coli bacteria was present in most of the samples, the levels were extremely low and not indicative of a significant load of sewage. There were also very low levels of ‘total organic carbon’, which is again indicative of the absence of a ‘reservoir’ of spill material at the assessed lakebed sites.
We are working with Tūwharetoa Māori Trust Board to determine what additional monitoring will be required.