Lake Omapere - in danger of "dying" a year ago - is now virtually free of an invasive weed that threatened to kill most of the aquatic life in the lake.
Northland Regional Council monitoring shows levels of oxygen weed in the 1200ha lake, about 4km north of Kaikohe, have dropped
dramatically since the weed problem was at its worst just over two years ago.
Less than 12 months ago the weed was threatening to choke the life out of the lake.
The weed has now been eradicated from most of the lake, regional council environmental monitoring officer Amanda Baldwin said.
But Maori trustees of the lake say a lot more work is needed to get the lake back to top condition.
Ms Baldwin said that in September 2000, the entire lakebed was smothering under as much as 5500 tonnes of weed.
The council attributes the drop in weed levels to a combination of factors, including the introduction of 20,000 weed-eating grass carp this year and, ironically, the increased presence of a potentially toxic algal bloom.
The surface-dwelling algal bloom has blocked most of the sunlight the weed needs.
Ms Baldwin said there was a real risk this year that increasing weed growth could kill most of the aquatic life in Lake Omapere.
With the weed risk now practically eliminated, attention has turned to drawing up a long-term management plan for the lake in general.
Central to this is a group of about 20 Lake Omapere trustees, appointed this year by the Maori Land Court on behalf of lake owners, the Ngapuhi iwi.
Over the past few months the trustees have held several preliminary meetings with interested parties, including local landowners, to help identify issues facing the lake and establish a management plan.
Lake Omapere Trustees environmental co-ordinator Kevin Prime said trustees hoped to have finished consulting landowners by the end of January. Mr Prime said it was good news that the weed had been controlled, but much more work was needed to return the lake to its former glory.
"It still looks murky and green and there's still a lot of work to be done. Next we've got to stop all the nutrients going into the water from the surrounding land."
As part of the lake's management, the regional council will continue monitoring weed and water quality.
"By reducing the weed, we have helped the lake in the long-term but the potentially toxic algal bloom is still there and will also require ongoing monitoring," Ms Baldwin said.
People are still advised not to drink water from the lake and farmers should continue to keep stock away from it and the nearby Utakura River.
- NZPA
Herald feature: Environment
Lake Omapere - in danger of "dying" a year ago - is now virtually free of an invasive weed that threatened to kill most of the aquatic life in the lake.
Northland Regional Council monitoring shows levels of oxygen weed in the 1200ha lake, about 4km north of Kaikohe, have dropped
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