The Whatawhata Integrated Catchment Management (ICM) Project is the longest continuously monitored before-after-control-impact (BACI) catchment-scale study in New Zealand. The study assessed the impact of catchment-wide land use changes on stream water quality/quantity and ecosystem health within several headwater catchments within and adjacent to the former-Whatawhata Research Station (WRS). Land use changes were implemented in 2001 and stream monitoring at ICM and pasture and native forest control (unimpacted) sites was conducted between 1995 and 2020 (the long-term environmental monitoring programme ended in June 2020). The long-term monitoring captured the before-and-after response of the catchment-scale land use changes, including timescales of responses and dynamics in response to natural events (e.g., severe weather).
The WRS has been the focus of over 100 environment-related publications, including international scientific journal articles, conference presentations, magazine, and internet articles.

Within the WRS there are two experimental sub-catchments (Mangaotama (2.7 km2) and Kiripaka (2.7 km2)). The ‘control’ Whakakai catchment (3.1 km2), which is located within a forest reserve immediately adjacent to the WRS, is entirely indigenous regrowth forest (broadleaf/podocarp). The most significant ICM-related land use changes took place in the Mangaotama catchment and most monitoring sites were located within this sub-catchment. As the Whakakai catchment remained unchanged over the entire study period it, provides base information that we can compare the Mangaotama catchment results to.
This dataset includes all the water quality sampling data collected at all 11 long-term monitoring sites (5 within the Mangaotama catchment, 5 within the Kiripaka catchment, 1 within the Whakakai catchment). Most data were obtained from monthly grab samples that took place between 1995 and 2020. Location details of these sites and what land use changes took place in the catchment above them are presented in the attached files.