With reference to examples you have studied, assess the effectiveness of attempts to control water pollution. Water pollution is the contamination of areas of water, such as rivers, lakes and groundwater. It affects plants and organisms that live in these areas and can be damaging to the health, and survival of them. Water pollution occurs when pollutants are directly or indirectly discharged into the water without being treated. The area of Rotorua – New Zealand contains 17 lakes, some of which experience, or have experienced varying levels of water pollution.
Lake Rotorua has had serious pollution problems, more than any other lake in New Zealand. In 1969 Rotorua had a population of over 50,000 people. They contaminated the lake with sewage for many years and it was described as an “un-flushed toilet. ” Today most of the pollution is from fertilisers that runoff from farmland. As the diagram shows Lake Rotorua and Lake Rotoiti are linked – by the Ohau Channel. So what happens in Lake Rotorua affects the water quality of Lake Rotoiti. However they face different issues that require different solutions.
Lake Rotorua’s city has more than 55,000 people living on the shores, with smaller communities scattered around its edge. On average there is an extra 15,000 visitors a day as its tourism industry attracts people from all over the world. Over the years Lake Rotorua’s water quality has decreased despite a lot of environmental work. Water quality improved after a high-tech sewerage system was installed for Rotorua city in the late 1980’s. It has since deteriorated again from an increase of nitrogen in the groundwater.
With so many people living in the catchment nutrients from sewage are an ongoing issue. This is being undertaken by a range of actions from the Council. An $18. 5 million reticulation scheme for eastern lakeside communities is in progress, and there has been a major upgrade of the Rotorua City sewage plant which has now been completed. The Council has introduced new rules for high-tech septic tanks in rural areas and $70 million has been spent upgrading or adding sewage reticulation around the lakes.
Along with the Council the local community has had increased involvement, awareness and education. The local Iwi, Federated Farmers, Rural and Urban landowners, tourism agencies and Fish and Game all took part in the preparation of an action plan. It began with providing an education to schools to teach students (and teachers) to protect their Lake from becoming polluted. In the city streets are swept frequently to remove rubbish and oils so the pollutants don’t run into the lake. Storm-water is filtered to remove leaves and other rubbish.
Eutrophication has been a major problem due to intensive farming, which often produces more nutrients than the soil can easily absorb. This excess either flows overland into waterways or leaches into groundwater which eventually feeds into springs, streams and then into the Lakes. This has caused algal blooms in some Lakes, making the water undrinkable. All 17 Lakes have had risks, or experienced these blooms, and each of them has different water quality problems and steps to improve the water quality.
For example – Lake Rotoiti has severe cyanobacterial (blue-green algae) blooms which have become more persistent in the past few years. This is due to receiving nutrient rich water from Lake Rotorua. The plan proposed is to divert an inflow of water and to build better sewage treatment areas for local people. The effectiveness of all these plans has been shown as the quality of water has improved – slowly over time. Figures set by the Regional Water and Land Conservation are slowly being met, as research is undertaken to preserve the Natural Environments.
Trophic Level Index is a measure used in New Zealand to measure the nutrient status of lakes. The lower the number, the better the water quality. It has been proven that targets of lower Trophic Levels are being reached. Lake Rerewhakaaitu has almost reached its target of 3. 6 as it currently sits at an average of 3. 7. With constant monitoring, research and implementation of plans to protect the lakes, they will continue to have better water quality and pollution will become more manageable and healthier.