Action Plan approved for Lake Tikitapu

The Rotorua Te Arawa Lakes Strategy Group has approved an Action Plan for Lake Tikitapu (Blue Lake).

Lake Tikitapu is one of the 12 Rotorua lakes in the Bay of Plenty. The lake is safe for swimming, however some indicators suggest that the lake’s water quality has been getting worse since monitoring began in 1992. More people visit Lake Tikitapu every year, placing stress on old septic tank facilities which has been causing nutrients to leach into the lake.

A draft Action Plan was released in April, with five stakeholders providing feedback. Most were supportive, but raised several concerns.

The draft Action Plan describes the water quality in Lake Tikitapu, and identifies nutrient reduction targets to achieve the objective outlined in the Regional Water and Land Plan. It was developed from information provided at a stakeholder workshop which identified social and economic pressures on water quality, and the best possible future state for Lake Tikitapu.

It also identified barriers and possible solutions to maintain or enhance lake values and discusses whether science and planned actions are adequate to improve water quality. The key action of reticulating sewerage of septic tanks was completed in October 2010 and should achieve the required nutrient reduction, the meeting was told.

Overall, stakeholders generally agreed with the approach taken, but raised three issues – the impact of tree harvesting on amenity values and water quality, nutrients from stormwater and the potential effects from increasing numbers of lake users.

Current science did not suggest remaining tree roots and off-cuts from exotic forests affected nutrient inputs into the lake, and the commercially operated exotic forest exported no more nutrients than native forest, the Group heard. There were no feasible nutrient reduction options that could be generated from either native or exotic forests.

Current tree harvesting around the lake had a District Council resource consent, with conditions protecting the amenity value of the lake. While the Action Plan could recognise the amenity value of the lake, its focus was solely on improving water quality.

The lake’s nutrient budget suggested stormwater was one of the three major sources of nitrogen input to Lake Tikitapu. Stormwater from the reserve and car park was estimated to be adding 4kg of phosphorous and 310kg of nitrogen to the lake each year. Increased use of the reserve and the car park could add various pollutants to stormwater, so it has been added as an area to be monitored if water quality did not improve as expected.

Visitors could affect water quality by using toilet facilities, and possibly contribute other waste into the stormwater system, but sewerage reticulation was likely to address the problem, the Group heard.

It agreed to explicitly recognise that the community valued the lake surroundings, add forest harvesting activities as one of the areas to be looked at for water quality change and add stormwater and visitor activities as areas to be looked into if water quality did not improve.