Lake Tarawera, near Rotorua. Photo: Laura Smith / LDR
Rotorua Lakes Council has apologised for publishing inaccurate information about its $29 million Lake Tarawera sewerage scheme, as a former TV presenter claims it is producing "propaganda".
Tarawera resident Geoff Thomas - of Outdoors with Geoff fame - called the council's claim "more than 200,000 litres" of wastewater soaks to the ground daily and enters the popular fishing lake "scandalous".
The council says the figure is based on industry estimates of household water use, but acknowledged it had no data on how many properties at the popular holiday spot were permanently occupied.
The scheme followed a finding about a decade ago that reticulated sewerage would reduce nutrient levels and pathogens flowing into Lake Tarawera.
The about 450 affected households either needed to connect to reticulated sewerage or seek consent to upgrade their wastewater systems - though consent was unlikely to be granted if reticulation was doable.
Connection to the reticulation scheme was expected to cost households about $50,000 each, but costs are not finalised.
Construction was nearly complete but had been interrupted by protests by mana whenua concerned about the pipeline route.
The district council recently placed posters in public toilets around the lake listing "the facts" about the scheme.
"Lake Tarawera water quality is declining," the posters were headlined. "Every day more than 200,000 litres of sewage from septic tanks leaks into the ground and enters Lake Tarawera."
The council previously said the figure was 300,000 litres and between 200,000 litres to 300,000L.
Geoff Thomas has lived at Lake Tarawera for the last 12 years. Photo: Laura Smith / LDR
Thomas said he viewed the figures as "misleading", "propaganda" and "physically impossible".
"How are the figures arrived at, a guess? The only raw sewage we have ever seen running into the lake has been from the council's own toilets at Stoney Pt and The Landing."
He understood most of the lake's nutrient load came from other sources such as farm runoff, forestry and geothermal systems.
"Everyone agrees the sewerage reticulation scheme must be completed, but to lay the blame for 'lake water enrichment' on residents' septic tanks is scandalous."
"People will say, 'I'm not letting my kids swim in that lake.'"
The lake's water quality is rated "excellent" on Land, Air Water Aotearoa's swimming website.
Tarawera resident Tracey McLeod said, in her view, the council had "grossly exaggerated" the figures, and used false information that septic tanks were "banned" since 2017.
Its website, which has since been changed, said they were disallowed under the regional council's Plan Change 14 - a plan that never progressed past the draft stage.
Sewage-to-lake figure based on estimates
Infrastructure and environment group manager Stavros Michael said the council had taken down the posters not already pulled down by others.
Michael said information about septic tanks being "banned" was removed from its website.
"We acknowledge this is inaccurate and apologise for any confusion that has been created - that was certainly not the intention."
Use of the word "leaks" was wrong and should have been "leaches".
He said the leaching estimate was based on average estimates of water use and how septic tanks work.
As household wastewater entered a tank, the same amount of liquid leached out an outlet pipe into a ground soakage system and down toward the water table.
Infrastructure and environment group manager Stavros Michael at a September meeting. Photo: Laura Smith / LDR
He said the estimate was based on 450 households consuming an industry estimate of 700 litres of water a day. The number of households was reduced by 20 percent to allow for water used outside and "some properties not being permanently occupied".
This resulted in an estimated average of 252,000 litres a day.
Local Democracy Reporting asked for a more thorough explanation, and clarity on the difference between the council's 80 percent permanent occupancy estimate and reports in 2015 and 2017 that estimated 25 percent of 390 Tarawera houses were permanently occupied.
Michael said the number of homes connecting to the scheme came from the rating database, and the 20 percent was an estimate as it "does not hold data on how many homes are occupied full-time, part-time or are rented out as holiday accommodation".
He said the other reports were not the district council's so it could not speak to those numbers.
The 2017 report was prepared for the Bay of Plenty Regional Council and the 2015 one was the regional council's Tarawera Lakes Restoration Plan.
Ray White real estate licensee salesman and Tarawera resident Norman Donald said permanent occupancy had increased over the years and 35 percent would be a safe estimate.
Michael said the posters were intended to give lake visitors key information about the scheme in light of concerns about the pipeline route.
Michael said reticulation and maintaining sewerage and stormwater discharge infrastructure was the council's key contribution to lake water quality.
A request for explanation of how the scheme was justified in relation to costs and benefits was not answered.
Regional council land and water compliance manager Matthew Harrex said its view was the district council oversimplified its rules and should have specified resource consent for new or upgraded septic tank systems was unlikely to be granted where reticulation was available.
The council's plans and policies supported reticulation but the discretionary rule allowed for situations where a connection was not technically feasible.
Michael said in response that when the community "asked the council to initiate a reticulation system" for Tarawera, people were aware septic tanks alone would be non-compliant, consents for compliance upgrades were unlikely to be approved where reticulation was nearby, and nearly 40 percent of properties were found unsuitable for upgrades because of steep slopes or other features.
Regional council Rotorua catchments manager Helen Creagh said all 10 actions from its restoration plan for Lake Tarawera had been or were being implemented, including reticulation and developing environmental management plans for all farms in the catchment.
- LDR is local body journalism co-funded by RNZ and NZ On Air.