The two companies charged in relation to the Waihi Dam denied their charges yesterday.
The dam began discharging silt into the Waiau River near Wairoa in December after a sluice gate was damaged in a storm in September.
Eastland Networks Limited and Abyss Limited were charged in relation to the works carried out on the Waihi Dam and the subsequent discharge of silt into the Waihi and Waiau Rivers, but have both denied the charges.
Yesterday they pleaded not guilty to four alleged offences arising out of contamination of the Waihi River between December 2015 and February 2016.
Each party face charges of disturbance of a bed of a lake or river (under Section 13[1][b] of the Resource Management Act) and the discharge of contaminants into water (under section 15[1][a] of the Resource Management Act).