Biodiversity Strategy - Gosford City Council - NSW Government

The Hawkesbury River
The Hawkesbury-Nepean River system is the State's largest estuary. The river is tidal to
Yarramundi Road Bridge, a distance of 145 km upstream. The non-tidal reaches (ie. upstream
of the Yarramundi Road Bridge) are the Nepean River system; the tidal component is the
Hawkesbury. The Hawkesbury-Nepean River system is fed by the catchment of the
Hawkesbury Valley (21500 km2). Most of the northern and western areas of the Hawkesbury
Valley are heavily timbered and comprise rugged and mountainous terrain with land slopes
greater than 15°. The area that lies within Gosford is the area north of the local government
boundary line, running down the middle of the Hawkesbury from Wiseman's Ferry downstream
to West Head (Broken Bay) then across to the northern headland (Box Head). The major
tributaries of the Hawkesbury, within Gosford's LGA, include Mangrove, Mooney Mooney, Mullet
and Patonga Creeks.
A Strategic Plan for the Management of the Hawkesbury Nepean Catchment and River System
was developed by the former Hawkesbury Nepean Catchment Management Trust, whose
operations were absorbed into the Department of Land & Water Conservation in April, 2001. In
accordance with a direction from the Minister for Land and Water Conservation the Strategic
Plan has been used as the basis for the content of the Hawkesbury Lower Nepean Catchment
Blueprint (DLWC, 2003).
The Blueprint identifies a raft of management targets and actions. The responsibility for
implementing many of these actions is shared amongst stakeholders: Councils, State Agencies
and the community working in partnership. Key issues identified in the Blueprint relate to:
managing water quality and quantity – sharing water with the environment, and between people;
aquatic and terrestrial biodiversity and their adequate conservation and rehabilitation; the way
the land is used to meet social and economic needs while protecting the environment upon
which all life depends; sustainability of development; public and private investment; and
community participation in catchment health (DLWC, 2003).
The brackish wetlands of the lower Hawkesbury are regionally significant (Figure 6.8),
contributing nearly half of the Sydney region’s remaining area of mangroves and saltmarsh and
more than 80% of its remaining Swamp Oak forest (Stricker and Wall, 1994).
Many of these wetlands are identified and protected in the Sydney Regional Environmental Plan
(SREP 20) (Department of Planning 1995). The REP specifies various classes of development
in wetlands that require councils to gain the concurrence of planning authorities before granting
development approval for works such as dredging operations, marinas and so on. In 1998
Gosford City Council commissioned Australian Water Technologies to undertake a wetland
management study of the Hawkesbury River Catchment within its municipality. The study
(Wetland Management Study in the Hawkesbury-Nepean Catchment) enquired into the types of
wetlands, ownership, what is affecting their condition and what can be done to preserve them
(AWT, 1998). It identified 52 wetlands in the LGA and described each site with information on
the following:
• Location;
• Wetland Type by listing the type of wetland vegetation present;
• Seasonality - whether the hydrological character of the wetland is ephemeral
seasonal) or perennial (permanent);
• Access to the site;
• Flora and fauna values;
• Level of disturbance;
Biodiversity - Technical Report Page 136