Zone 3 is located mid estuary between Swan Point and Rowella halfway along the Longreach section of the Tamar River estuary. This area features large silt bays with smaller rocky channels, especially around the Batman Bridge where the substrate is mainly cobble and reef (Lucieer et al., 2009). A prominent man-made feature in this section of the estuary is the Batman Bridge (Est. 1968) which spans 200m and connects the eastern and western shores of the estuary at Whirlpool Reach. Zone 3 has smaller rural communities along the shores of the Tamar with grazing, cropping, vineyards, orchards, wood processors and salmon farming all operating close to the estuary’s shore Zone 3 is also used for recreational activities such as swimming, boating, camping and fishing.
The salinity range for the 2010/2011 monitoring period was 3.0-29.0 ppt with the sampling depth ranging from 17-33 m. This zone within the estuary has less variation in salinity between surface and bottom samples, and thus could be considered to have a well mixed water column. This may be due to the zones location in the middle of the estuary and the geomorphology of deep rocky pools and narrow bends combing with powerful tidal influences. Although the water in this zone is well mixed a seasonal signal is still evident.