The Wairua River is one of Northland's largest rivers, rising in the hilly country north-west of Whangarei where it is known as the Waiotu. It is joined by several tributaries — including the Mataroa, Kaikonui, Kaimamaku, Waiariki, and Whakapara — before eventually merging with the Mangakahia River to form the Wairoa River. The paddleable section of interest runs approximately 15 kilometres and carries an average gradient of around 2.2 metres per kilometre (1:457).

The character of this stretch is defined by two distinct zones separated by significant waterfalls. Below each of the two waterfalls on this section, the river produces rapids reaching up to Grade 3. The upper rapids are notable enough that the Northland Canoe Club holds its slalom competitions there, drawing competitors from across the North Island. Below the upper rapids lies a large pool, after which the river flattens considerably before reaching the dam at Wairua Falls. The Wairua Falls themselves must be portaged — they are not runnable under normal circumstances — though at least one kayaker has been documented running the approximately 50-foot drop. Below Wairua Falls, further Grade 3 rapids exist, though access to this lower section is described as difficult. Some paddlers who run this lower section tow their canoes back up the hydro channel to the dam in order to re-run the rapids.

The flat water above the dam is large enough for powerboat use, though this section sees little recreational traffic. Access to the river can be gained from several road crossings. Jordan Valley Road off State Highway 1 (approximately 250 metres past the Hikurangi turnoff) leads to a bridge over the river where a marginal strip removes the need for landowner permission. Rushbrook Road provides another crossing with good water both upstream and downstream, though farmer permission is required there. The Ruatangata Road bridge, reached by turning off State Highway 1 near the Kamo Shopping Centre and driving approximately 20 kilometres, offers further access with fishable water in both directions.

The river is open to fishing year-round, unlike most Northland rivers which follow a seasonal 1 October to 30 April schedule, reflecting its status as one of the region's more significant waterways. Water quality has been noted as poor in at least one account describing the river as "dirty."