Five
Sites of Special Scientific Interest (SSSI) have been designated along the River Fal. The river rises on
Goss Moor which is both a
National Nature Reserve and part of a SSSI. The wetland habitats and western dry heath communities were formed, since the
Bronze Age, by the mining of the
alluvial tin deposits. South Terras Mine SSSI is also a
Geological Conservation Review (GCR) site of national importance and was once a commercial
uranium mine. The Crowhill Valley SSSI between
Grampound and
St Stephen is an
ancient woodland dominated by
sessile oak on the slopes, and of
willow and
alder carr on the floodplain which has a rich ground flora. The species list includes many ancient woodland indicators including
lichens such as
Parmelia endochlora. The Upper Fal Estuary and Woods SSSI is mostly within the tidal area of the river between
Tregony and
Turnaware Point and includes
mudflats,
salt marsh and ancient woodland. The mudflats support nationally important numbers of
black-tailed godwit as well as large populations of wintering waders and wildfowl such as
curlew and
golden plover. A series of transition zones occur from the salt marsh to
scrub, where young trees attempt to grow despite the threat of the highest tides, to ancient woodland on the higher slopes. These zones and the estuary itself are important for
otters. The lowest part of the Fal along with the
Helford River is designated as the Fal and Helford
Special Area of Conservation under the
Habitats Directive for the shallow bays and inlets, sandbanks and mudflats, and for its salt marshes. Part of the area is also designated as an
Important Plant Area and a SSSI (Lower Fal & Helford Intertidal) for the relatively undisturbed transitions from tidal mud through saltmarsh and scrub to woodland. Three institutional landowners that own land within Upper Fal Estuary and Woods SSSI include the
Duchy of Cornwall, the
National Trust (for example, the
Trelissick estate) and the
Diocese of Truro (via its
Diocesan Board of Finance). ==Water quality==