There is very little water taken from the Waiapu River and its tributaries. The high sediment load in the water means that there is not a great demand to use the water for drinking water supplies. Despite this there are occasions when local marae and small communities do utilise water from the catchment for domestic use. Livestock water supply is derived from the river and its tributaries by farmers allowing stock to have direct access to smaller streams that are tributaries of the Waiapu.
The shingle beaches of the Waiapu are constantly being replenished by gravel eroded from further up the river and provide a source of roading gravel that is used for the extensive network of rural and forestry roads within the catchment area.
The Waitahaia River is a tributary of the Mata River in the upper catchment of the Waiapu. This river is renowned for brown trout that are prized by visiting anglers who can afford to be flown into the fishing area by helicopter. The water quality in tributaries of the Waiapu such as the Waitahia is often higher due to the closer proximity to the Raukumara Ranges and the indigenous vegetation cover that is predominant.