The figure appears in demographic data produced to support Southern District Health Board's long-term strategic plan released this month for consultation.
Mr Kircher has taken exception to the figure, which he said would be used to make health funding decisions for Waitaki.
He said the district's population increased by 3% in the last census, which ''blew the other predictions out of the water''.
The increase, between 2006 and 2013, was partly because of demand for irrigation.
Mr Kircher expected the district to grow by up to 3% in the next five years.
He believed the agricultural economy would continue to drive population growth, and Oamaru's heritage quarter would attract new businesses and people.
Mr Kircher has written to the health board about the figure, as part of the Waitaki District Council's submission on the strategic plan.
Mr Kircher said the health board should base more services in Oamaru Hospital, and in particular send more patients to its under-utilised CT scanner.
''We certainly encourage the Southern District Health Board to better utilise the facilities we have in our area.''
Southern DHB planning and funding director Sandra Boardman told Radio New Zealand Waitaki's projections were being checked.
Mrs Boardman also said the projected population drop would not be enough to have affected services much.
