The ecology of the Hutt Valley: Forest variation in the Hutt catchment
The Hutt catchment has an area of 245 square miles, most of which is hilly and mountainous country above 1,000 ft. The average rainfall in the lower part of the valley (south of Te Marua) and on the Eastern and Western Hutt hills is 50-60 in.; eslewhere it is 80-100 in. or more, probably exceeding 150 in. at 4,000 ft. Originally more than 95% of the catchment was in forest. Today, approximately 42% (103 sq. miles) still carries primary forest, although nearly all of it is to a greater or less extent modified.