Publications: Research reports and publications

Lake Wairarapa — understanding the ecological past and present for future management

21 August, 2018
Cawthron Report No. 3157. Prepared for Great Wellington Regional Council

Waters S, Kelly D, Vandergoes M, Rees A, Li X, Cochran L, Homes A 2018. Lake Wairarapa — understanding the ecological past and present for future management. Prepared for Greater Wellington Regional Council. Cawthron Report No. 3157. 61 pages plus appendices.

Executive Summary:

Lake Wairarapa is a large, shallow lake in the Wellington Region. Cultural, ecological, recreational and natural character values make the lake nationally and internationally significant and protected in part by a National Water Conservation Order. However, routine monitoring indicates that the lake has poor water quality, with high total phosphorus concentrations and turbidity resulting in the lake been classified as supertrophic with a Trophic Level Index score of 5.4 (on a scale of 0–7, where a high score indicates poor water quality).

The Greater Wellington Regional Council (GWRC) is committed to increasing the understanding of lake ecosystems, in order to improve lake management. To this end the GWRC has partnered with Ministry of Business, Innovation and Employment (MBIE)-funded research programmes: Enhancing the Health and Resilience of New Zealand Lakes (led by Waikato University, Contract UOWX1503) and Our Lakes’ Health; Past, Present and Future (co-led by GNS Science and Cawthron, Contract C05X1707), to address key gaps in the understanding of the Lake Wairarapa ecosystem. This report presents the results and conclusions from three research projects which were undertaken as a result of this research partnership.

The key research components were:
1. investigating paleoecological history to gain insights into the historic reference state of Lake Wairarapa
2. determining the current species composition and distribution of macrophytes in Lake Wairarapa
3. understanding sediment quality by investigating legacy nutrients in lake sediments and potential for nutrient fluxes between lakebed surface-sediments and water column.