Zone 1 extends from the town of Launceston to north of Tamar Island in the upper estuary. The foreshore of this zone is the most heavily urbanised of the estuary, supporting an urban population of around 100,000. In the upper reaches of this zone there are direct freshwater inputs from the North Esk and South Esk rivers which drain approximately 10,000 km2 or 15% of Tasmania's land mass. Another major freshwater input is delivered from the Lake Trevallyn Tail Race hydro-electric power scheme. As a result, this zone has limited marine influence, with bottom waters only slightly more saline than surface waters.
Zone 1 is the shallowest section in the estuary where depth ranges from 5–8 metres with broad shallow tidal flats. The bottom habitat, like much of the Tamar estuary, is silt (Lucieer et al., 2009). The introduced Gambusia holbrooki (mosquito fish) inhabits areas in and around the Tamar Island wetlands. Due to the urbanised nature of the Launceston city area, there are many diffuse and point source pollution inputs to this zone including stormwater runoff and effluent from wastewater treatment plants. These inputs are represented in Zone 1 conceptual diagram (Figure 6). The Tamar catchment has a historic legacy of metal contamination from mining and smelting activities which continue to accumulate in the estuary’s sediments. The upper reaches of the estuary have a history of extensive dredging for navigational purposes and are an area of sediment accumulation. Sediments are delivered from the upper catchments and existing sediments are redistributed within the estuary. Zone 1 also has ship lift operating close to the Launceston CBD where ship repairs, maintenance, hull cleaning and painting occur. The Seaport Hotel, residential and restaurant precinct located on the southern bank of the lower North Esk supports a marina with permanent and visiting vessels using the mooring facilities.
Tourism Company Tamar Cruises operates two boat tours on the Tamar Estuary, one does a short run from the Seaport up into Cataract Gorge and back to the North Esk and the second a larger vessel operates a return cruise down river from Launceston to the Batman area in Zone 3. Rowing is a major recreational activity in Zone 1 with several school rowing clubs operating close to the city of Launceston. Another feature of Zone 1 is the Tamar Island wetlands located on the Western shore just north of Launceston. It provides habitat for a variety of birds, mammals, reptiles, frogs, fish and invertebrates, as well as being an important historic landmark in the early settlement of Launceston. It is part of the Tamar Conservation Area, which protects the Tamar River’s remnant wetlands.
During the 2010/2011 sampling period the water column in Zone 1 was well mixed and dominated by freshwater with little differences in salinity between surface and bottom waters. The freshwater inputs in this zone were much greater than during the previous 12 months (which saw bottom waters brackish in summer and autumn) reflecting the high rainfall and incidence of flooding during the 2010-2011 monitoring period.