Site RO1 – Tarawera at Lake Outlet

First draft May 2008: revised January 2009.

Site details

Hydrometric site number: 15341

Sampling Location: NZMS 260 V16: 168 297

Flow measurements: Records began in 1971. River flow measured by a slackline and stage is measured every 15 mins. The rating is stable and the maximum stage range is 0.64m. The maximum recorded flow is 15678 l/s, the minimum is 3844 l/s, and mean flow is 6740 l/s.

Sampling site: The water quality monitoring site is approximately 800m upstream of the recording site. The same sampling site has been used for all measurements. Periphyton measurements are made from the bridge. The invertebrate sampling site is approximately 1.1 km downstream. The substrates close to lake are mainly lake sand and suitable substrate can only be found lower downstream once velocities and stream slope increases. From 12 November 2008, the DO meter changed from the original YSI model 58 to the HACH Model HQ40d. The new meter employs a luminescent probe technology and stirring of the sample is not required to get a final, stable reading.

Catchment: The catchment consists of regenerating native bush (75%), forestry estate (15%) which is currently being harvested, farmland (8%) and housing (2%). Lake Tarawera is situated within a volcanic zone and there are some geothermal inputs. The is the outflow for Lake Tarawera. The lake is dominated by which erupted in 1886. The whole catchment was devastated and now consists of regenerating native bush, forestry estate and a small cluster of houses on the eastern shore. One of the major input streams flows through farmland while the other major stream exits Rotokakahi, a lake higher in the catchment. Long term monitoring by Environment has detected no change in the water quality of Lake Tarawera and therefore no impact is expected to have occurred in the water quality at sampling site RO1. Lake Tarawera is one of the iconic lakes of the lakes district and supports a world class trout fishery.

Site location

Invertebrate sampling site

Flow site

Water Quality sampling site

Site photos and sampling/assessment details

Looking upstream (16.10.2007).

Looking downstream (16.10.2007). Flow site is at end of ridge in background.

View from bridge (16.10.2007).