The Otepuni Stream and Waihopai River were also searched.
Still, nothing was found that gave any indication of Horn's whereabouts.
Sgt Martin said dive teams had not been used but it was something searchers would consider.
It was initially thought Horn would not be able to walk far due to his limited mobility.
He left Walmsley House, a rest-home in Richmond, early last Monday morning.
The latest information was that he was in Queens Park between about 10.20am and 11am.
Sgt Martin previously expressed concern Horn had got into trouble, such as being locked in a shed, and needed help.
However, because of a stroke, he was unable to communicate verbally.
Horn was believed to be wearing a black and red jacket and possibly a light-coloured polo shirt, gym shoes and sweat-pants or jeans.
Anyone with information should call police on 105 and quote event number P045508171.
If Horn is seen, call 111.