After a couple of years' respite, the algal bloom which plagued Lake Hayes for many years has returned.
Why it has returned is a mystery to the Otago Regional Council and it hopes a new study might be able to find the answers.
The council had been in touch with the University of Otago to see if a PhD study on the lake could be done, and offering to pay 50% of the cost, council environmental information and science director John Threlfall said.
However, as the university was unable to pay the other 50%, it was decided the council would pay the full $12,000 cost of the project, he said.
It was ''very good value for money'' and would build on the work already done to give a further understanding of the lake and why the bloom had returned, he said.
''If we did the study it would be more expensive and not be as intensive.''
While a solution to the problem had been discovered - capping the nutrients on the lake bed - it would be very costly and have to be repeated every three years.
A less expensive solution needed to be found or people would have to live with a brown-coloured lake, he said.
The bloom did not appear to be toxic.
