Lake Taupo in the Waikato Region continues to have high quality, clear water that is safe to swim in. It takes a long time for changes in the Lake’s water quality to show up. Environment Waikato’s monitoring of the Lake shows rising nitrogen levels in the bottom waters of the Lake. This could affect the Lake’s water clarity, and plant and animal life. On this page:
How clean is the Lake?
Environment Waikato tests the water from both the Lake’s edge and a deep water site. Check out our monitoring results that show that Lake Taupo continues to have high quality, clear water that is safe to swim in.
However, since the mid 1970s, nitrogen has built up in the bottom waters of Lake Taupo. This could lead to reduced water clarity, blooms and scums of algae and could affect the amount of dissolved oxygen needed by the plants and animals that live in the Lake. Find out about the importance of dissolved oxygen in our glossary.
It takes a long time for changes to show
More than 30 streams and rivers drain into Lake Taupo from the catchment. An annual rainfall of between 1250 mm and 2000 mm over much of this land gives Lake Taupo a relatively constant source of new water.
But because it is such a large, deep lake, it can take a droplet of water 11.5 years to pass through the Lake before it flows out into the Waikato River. This means changes in water quality can take a long time to show up in monitoring results.
Ecosystems at risk
Lake Taupo is home to many native plant species, at least 31 species of aquatic birds and a number of native and introduced fish, including:
- koaro
- the common bully
- the common smelt
- rainbow trout
- brown trout.
Catfish have been recorded in the Lake since 1985. Catfish are a pest because they feed on freshwater snails, koura, bullies and smelt. They have been known to attack juvenile trout.
Native plant species don’t compete well with introduced aquatic weeds. Oxygen weed, pondweed and hornwort are a growing problem in the Lake. These water weeds spread rapidly. Waternet is present in Kinloch marina, but low nutrient levels in the Lake mean it is not likely to become a problem weed.
Whangamata Stream – a real success story
Since 1976, Whangamata Stream (at the northern end of the Lake) has been fenced off and helped to revert to its natural state. This is one of Lake Taupo’s most important trout–spawning streams. It is now a haven for native plants and wildlife. The native plants and trees now growing on its banks have greatly reduced the amount of sediment getting into Lake Taupo.
As native plants such as flax, toetoe, and cabbage trees flourished they shaded out the weeds that often blocked the stream. Fish and other wildlife returned, and the first fernbirds in the area were recorded in the early 1990s.
This work was part of the Lake Taupo Catchment Control Scheme, designed to reduce erosion and sediment input to the Lake. The Scheme was originally funded by both the Government and landowners, and is now administered by Environment Waikato.
Find out more about Project Watershed, which includes Environment Waikato's land and river based works and services (like the Lake Taupo Catchment Control Scheme) in the greater Waikato catchment.
Keeping the Lake clean and weed free
Everyone can help look after Lake Taupo’s water quality by being careful about what they put into the stormwater drains. Stormwater is not treated and drains straight into the Lake, or into rivers and streams that flow into the Lake. Taupo District Council aims to reduce pollutants going into the Lake, local rivers and streams through stormwater drains.
Landowners living around the Lake can help by planting and fencing stream banks. Plants help to filter out nutrients and sediment in runoff, as well as providing shade and habitat for wildlife. Fencing streams prevents stock from:
- muddying the water
- depositing waste in streams
- causing bank erosion.
Boat–owners also need to carefully wash down boat keels, motors and trailers before putting boats into Lake Taupo. This reduces the chances of introducing water weeds.
If boats have seam leaks or loose stern glands, oily bilge water often dribbles into the Lake. Automatic bilge pumps can release dirty water directly into the Lake. To prevent these problems, boaties need to keep boat bilges clean and dry and ensure they dispose of rubbish and sewage on–shore.
Lake Taupo fact file…
- Lake Taupo was formed by a series of eruptions, the most recent of which - around eighteen hundred years ago - blasted out about 60 cubic kilometres of earth, rock and mud, leaving a massive crater.
- More than 30 rivers and streams flow into the Lake, with only one outlet – the Waikato River.
- The full name of the Lake is Taupo–nui–a–Tia – the great cloak of Tia. Tia, one of the great fighting chiefs of the Arawa Canoe, is credited with discovering the Lake.
- Lake Taupo is 30 km wide and 40 km long, its deepest point is approximately 160 metres, it contains 59 cubic kilometres of water and is between a minimum of 355.85 metres and a maximum of 357.20 metres above sea level (depending on inflows and hydro-electric activity).
- Lake Taupo is 622 square kilometres in area. Its catchment is about five times the size of the Lake.
- The entire Lake Taupo catchment, including the lake, is 3487 square kilometres – 14 percent of the Waikato Region.
You can help!
- Don’t put everyday household or industrial products such as used oil, paint, pesticides, detergents or disinfectants, toilet cleaner, dairy products, fats and edible oils, down stormwater drains.
- Wash your car on the lawn so that soapy water soaks into the ground.
- Clean up chemical spills around the home by soaking up the mess.
- Take unused paint and domestic garden sprays to recycling centres.
- Use rubbish bins for your litter.
- Boat owners should dispose of rubbish and sewage on-shore, wash boat keels, motors and trailers carefully to remove water weeds and maintain bilge pumps to reduce oil leaks.
Place an order if you would like a published paper copy of ‘Lake Taupo – A National Treasure’.