WETLANDS

Wetlands assessment, management and rehabilitation

360 Environmental undertakes wetland assessments on behalf of various Clients. Wetlands in the Swan Coastal Plain exhibit a seasonal variation in water depth, flow and water quality in response to seasonal rainfall (Hill et al., 1996) and therefore assessment of each wetland is required.

The Swan Coastal Plain, in its entirety, extends from Dongara to Busselton (Gentilli and Fairbridge, 1951; in Hill et al., 1996). On the Swan Coastal Plain the basin wetland types of sumplands and damplands are the most numerous. In terms of area, the most dominant wetland type is plausiplain (Hill et al., 1996).

Wetland management categories (Department of Environment and Conservation’s (DEC) Geomorphic Wetlands Swan Coastal Plain dataset) include:

  • Conservation Category (CCW);
  • Resource Enhancement (REW);
  • Multiple Use Wetland (MUW);
  • RAMSAR protected wetlands; and
  • Environmental Protection Policy (EPP) Lakes.

The global geomorphic wetland classification system is based on characteristics of landform and water permanence (Semeniuk CA & Semeniuk V, 1995). The EPA has estimated that some 80 percent of the wetlands on the Swan Coastal Plain have been lost and the remainder heavily modified. Wetlands are now widely recognised as wildlife habitats and are among the most biologically productive and biologically diverse habitats on
the planet (EPA, 2004).

The key components of the scope of work undertaken by 360 Environmental for various wetland projects include:

  • Wetland mapping;
  • Prepare wetland management plans in accordance with DEC wetland management branch guidelines – ensures wetlands are protected both during and post construction of large scale infrastructure;
  • Describe and assess wetland values, functions and attributes of the wetlands of conservation significance (i.e. CCW, REW, EPP and Ramsar) that will be potentially affected, and describe them in a local and regional context;
  • Vegetation mapping;
  • Invertebrate monitoring;
  • Determine variations between actual and mapped wetland boundaries and provide annotated plans and maps as
    appropriate;
  • Provide recommendations to reclassify wetlands (if and as appropriate);
  • Undertake and coordinate reclassification;
  • Undertake wetland restoration and enhancement projects;
  • Determine appropriate buffer zones commensurate with land use;
  • Mosquito management;
  • Liaison with the Department of Environment and Conservation; and
  • Describe and provide offsets (consistent with EPA Position Statement Number 9 and 4, Offsets and Environmental Protection of Wetlands).

The following provides a summary of some of 360 Environmental’s wetland projects:

Nicholson Road Wetland Restoration Program

Key components included:

  • Management of wetland reclassification and associated community consultation;
  • Water quality management, including dewatering and acid sulphate soils from adjacent infrastructure activities;
  • Weed, fire and rubbish control management;
  • Rehabilitation management, monitoring and maintenance;
  • Fencing and access management;
  • Monitoring weed and dieback infestation post-construction; and
  • Annual progress reporting.

Thomsons and Kogolup Lakes Rehabilitation Management

Rehabilitation program incorporating planting of some 100,000 seedlings, fencing and weed control and maintenance for an area between Thomsons (RAMSAR protected wetland) and Kogolup lakes. This work Included a tortoise relocation plan for construction activities associated with the Perth Desalination Integration Projects.

Wetland in the Northwest of Western Australia

Lake Argyle is an internationally protected wetland with significant ecological attributes. A detailed macrobenthic assessment of the tributaries to Lake Argyle (Smoke and Limestone Creeks) was completed between 2000 and 2004.

Residential Subdivision

Wetland management undertaken for the included:

  • Preparation of a Wetland, Drainage and Nutrient Management Plan including:
  • Implementation of appropriate drainage design and nutrient control;
  • Construction wetland management;
  • Dieback, weed, access, fire and rubbish control;
  • Preparation of a Vectors and Nuisance Management Plan and project management of mosquito control processes, including monitoring and control; and
  • Preparation of a Wetland Rehabilitation Management Plan.

Wellard Wetland Management

Private land development - wetland survey and assessment and associated buffer report for a  conservation category wetland. The wetland vegetation was mapped and a weed control program established.