2022:920 - River Foyle, Lifford, Donegal

Underwater Archaeological Impact Assessment (UAIA) of the River Foyle was undertaken as part of the pre-planning requirement for a Riverine Community Park, proposed as a cross-border Community Park within Lifford, Co. Donegal, and Strabane, Co. Tyrone (divided by the River Foyle).

The onsite survey was primarily focused on the impact locations associated with a proposed slipway and pedestrian bridge planned for the project. However, the assessment area also extended along the banks of the River Foyle as follows:

• 800m section of intertidal foreshore and bankside areas on the northwest (Lifford) side of the River Foyle; ITM 633654E, 898493N – ITM 634011E, 898980N.
• 600m section of intertidal foreshore and bankside areas on the southeast (Strabane) side of the River Foyle; ITM 633637E, 898400N– ITM 634090E, 898894N.

A systematic visual survey of the assessment area was carried out over two Low Water Tide cycles, extending beyond the boundary identified for the proposed development. The onsite work included an intertidal/bankside walkover, waded/snorkel survey (where water depth was <500mm), and dive survey of the sub-tidal areas (where water depth was >500mm).

Targeted metal detection was also employed to assess the degree of ferrous and non-ferrous metallic debris present within a series of sample areas.

Existing riverine topography was recorded (bed/bank profiles), along with any in-water features of interest that were observed. Examination of the bank structure on the north-west side of the river channel corroborates a cartographic observation that this area was subject to reclamation: a steep-sided, artificial, bank structure delineating the channel on this side of the river. The structure comprises a deep deposit of silty-sand (3m+), interspersed with rounded pebbles/cobbles. Frequent modern debris is present with the upper parts of the structure, while older (nineteenth-century) material can be observed within the lower parts of the bank, for example, pieces of semi-dressed limestone masonry and wrought-iron gate fragments.

Two fragments of logboat (dug-out canoe) were discovered as part of the underwater survey, located on the north-west side of the waterway, positioned in relatively close proximity. Both represent redeposited items, lying on the surface of the riverbed close to the north-west side of the River Foyle, having most likely floated downstream during recent floodwater events. The fragments were recovered to surface in order to undertake an initial assessment/carry out primary recording; being later securely relocated to a suitable sub-tidal section of riverbed (positioned outside of the immediate impact area associated with proposed development).

The UAIA was carried out on 7 and 8 April 2022.