Regional lakes
Lake Tomarata
On this page:
- About Lake Tomarata
- How and when did this lake form?
- How healthy is Lake Tomarata?
- Threats to Lake Tomarata
- What is the ARC doing?
- Technical Publications
About Lake Tomarata?
Aerial view of Lake Tomarata looking north-west
The land to the north and east is covered by mature exotic forest, although much of this has been felled recently. The land to the south and west is covered by extensive swampy wetlands, with pastureland beyond that is used mostly for dairying. The wetlands provide an important habitiat for bittern, the shy fernbird, and possibly the banded rail. Native black mudfish were also discovered in the wetlands in September 2004. These had not been seen in the area for over 50 years.
There are no obvious streams or rivers flowing into or out of the lake. The lake water is quite brown, due to the amount of peaty organic material from the wetlands.
In 1999 a survey of the vegetation around the lake found the rare wire rush, previously thought to be extinct in the Auckland region. Other native vegetation included two types of sedge, raupo, and umbrella fern, with manuka further from the shoreline. Native submerged aquatic plants were established up to water depths of about 6.5m.
Lake Tomarata is a popular recreation site and is easily accessible. There is a boat ramp at the lake, as well as BBQ and picnic tables, changing facilities and toilets. The eastern side has small sandy beaches and provides safe swimming for young children.
Facts
| Location guide | About 20km north-east of Wellsford, close to the east coast of the North Island of New Zealand. See location map of Lake Tomarata |
| Surface area | About 16 hectares, with a similar area of neighbouring wetland. |
| Maximum depth | About 5m |
| Catchment area | About 83 hectares |
| Type of catchment | Pasture (54%) Exotic forest (17%) Native forest/scrub (29%) Urban (none) |
| Surface water temperature | Average 19.1°C |
| Number of sampling sites | One site, but water samples are collected at two different depths. |
How and when did this lake form?
Lake Tomarata is a dune lake. It used to be much larger. The extensive swampy wetlands around the lake shows the extent of the original lake.
The water in the lake accumulates from rainfall and seepage from the surrounding catchment area through the sandy lake bottom and wetlands.
How healthy is Lake Tomarata?
Since 1998, the quality of the lake water has been monitored as part of our State of the Environment (SoE) Lake Water Quality monitoring programme.
The quality of any lake water is shown by its trophic state.
The water quality at Lake Tomarata has declined to eutrophic (murky, with higher amounts of nutrients and algae).
| Microptrophic | Oligotrophic | Mesotrophic | Eutrophic | Supertrophic | Hypertrophic | |
| 2006/07 | x |
| ||||
| 2005/06 | x |
Threats to Lake Tomarata
The most significant problems at Lake Tomarata have been, or currently are the:
- Decline in water clarity. A 1998 study recorded the water clarity as more than 3.5m. However, in 2008 Fish & Game reported this had fallen to about 0.5m, down from an average of 1.5m between 1993 and 2005. The decline was first noticed in 2000 but has occurred more rapidly since late 2004.
- Collapse of the submerged aquatic plant community. The submerged aquatic plants that were growing in the lake during the 1999 survey have disappeared, even though there is enough light for them to grow. This lack of plant cover means that the lake no longer provides good habitat for trout so Fish & Game may not release any more trout into Lake Tomarata after 2008. The plant community may recover if the pest fish can be controlled and if the water clarity can be returned to its original level.
- Pest fish. The coarse pest fish, rudd, were released illegally and are thought to have caused the loss of the aquatic algae that carpeted the lake bottom in 1990. These fish may also have contributed to the recent collapse of the submerged aquatic plants, and the declining water clarity.
What is the ARC doing?
- In 2006, the ARC commissioned NIWA to help develop a regional management plan for freshwater weeds and pest fish. This suggested that the submerged aquatic plants could be re-established inside caged areas on the lake bottom. The cages would protect the lake bottom from disturbance by the fish and allow the plants to grow again.
- Since September 2004 the ARC has carried out annual surveys of the black mudfish in the Tomarata wetlands as part of its Regional Status and Trends monitoring programme.
- The water quality is sampled once every two months as part of our State of the Environment (SoE) Lake Water Quality monitoring programme. Find out more about the Lake Water Quality monitoring programme.
Technical Publications
The ARC has a number of technical publications relating to this subject. Follow this link to see the full list of ARC technical publications.
