This report presents the results of the 2020/2021 annual monitoring, undertaken from 11-15 December 2020. While there was some intertidal recovery from the widespread deposition of soft muds recorded in January 2020, there was degradation in other areas. Of particular concern was a thick slurry of deposited fine sediment and a high percentage of mud (67%) covering previously sandy intertidal flats at Kakaho, with 21.5 mm of intertidal deposition over the previous 11 months, the largest mean annual increase recorded for that site since monitoring began in 2007/2008. Decreases in the spatial extent of intertidal mud near Horokiri and Pāuatahanui streams coincided with significant increases in subtidal deposition, indicating that mud mobilised from the intertidal zone is deposited in nearby subtidal areas.

Reference: Roberts KL, Rabel H, Stevens LM. 2021. Te Awarua-o-Porirua Harbour Sediment Plate Monitoring 2020/2021. Salt Ecology Report 061, prepared for Greater Wellington Regional Council, March 2021. 24p.