Summary of Effects

This chapter summarises the environmental impacts that have been identified within this ES which are presented in Table 10.1 to Table 10.6. The table cross references mitigation identified in Table 11.1 to Table 11.11 to reduce the impacts then details the significance of the effect post mitigation. Impacts and effects are adverse unless otherwise stated. Those residual effects that are considered to be significant are shown in bold in the “Significance” column of the tables.

The tables identify significant residual effects for demolition of the historic masonry bridge; unrecorded remains at Lagganbane; loss of ancient woodland; loss of Daubenton’s bat and soprano pipistrelle bat roost; construction effects on Allt Lagain Bhain and cumulative construction effects on ecology and the water environment.

Table 10.1 Cultural Heritage
Potential Impact Mitigation no. Value/sensitivity of receptor Duration of impact Magnitude Significance
Demolition of trunk road bridge 8 Low Permanent Major Slight
Demolition of historic masonry bridge 5, 6, 7, 8 Medium Permanent Major Moderate
Disturbance or damage to Chapel, Torgyle house and Glenmoriston footprints during works 3, 4, 8 Medium Temporary No change Neutral
Disturbance or damage to unrecorded remains at Lagganbane 3, 4, 6, 8 Medium Temporary Permanent Minor to Moderate Slight to Moderate
Table 10.2 Ecology and Nature Conservation
Potential Impact Mitigation no. Value/sensitivity of receptor Duration of impact Magnitude Significance
Potential to impact designated sites 1, 2, 12, 43 International Temporary See Appendix D Not significant
Loss of ancient woodland and trees. 9, 43 County Permanent See Appendix D Significant at County scale
Impact on juniper 10 Local Permanent See Appendix D Not significant
Disturbance of otter 13,14,15,16,17,18,19,20 County Temporary See Appendix D Not significant
Loss of Daubenton's bat roost 13,18, 21, 22, 23, 24, 25, 26, 27, 28 County Permanent See Appendix D Significant at County scale but with potential to be not significant
Loss of soprano pipistrelle bat roost 13,18, 21, 22, 23, 24, 25, 26, 27, 28 Local Permanent See Appendix D Significant at Local scale with potential to be not significant
Potential to disturb / affect freshwater pearl mussels 13, 29, 31 Local (Allt Lagain Bhain and River Moriston to 150 m downstream of confluence). International (rest of River Moriston) Temporary See Appendix D Not significant
Impact on pine marten 20, 32 County Temporary See Appendix D Not significant
Impact on Atlantic salmon 13, 29, 31, 33, 34, 62 Regional Temporary See Appendix D Not significant
Disturbance of badger 13, 20, 35, 36, 37, 38 Local Temporary See Appendix D Not significant
Disturbance of breeding birds 13, 39, 40, 41 Local Permanent See Appendix D Not significant
Damage to wood ant colonies 13, 42 Local Temporary See Appendix D Not significant
Table 10.3 Landscape Effects
Potential Impact Mitigation no. Value/sensitivity of receptor Duration of impact Magnitude Significance
Loss of trees 48 N/A Permanent Negligible Neutral
Reprofiling of land 45 N/A Temporary Moderate Slight Adverse
Widening of trunk road/bridge 43, 47 N/A Permanent Negligible Neutral
Loss of old masonry bridge None achievable N/A Permanent Major Moderate Adverse
Construction 44, 46, 49 N/A Temporary Negligible Neutral
Table 10.4 Water Quality (Construction)
Potential Impact Mitigation no. Value/sensitivity of receptor Duration of impact Magnitude Significance
Allt Lagain Bhain - Decrease in water quality from site runoff 31, 50, 52, 54, 55, 56, 57, 58, 59, 60, 61, 62, 66, 68, 70, 81 Very High (downstream of road bridge). High (upstream of road bridge) Temporary Minor Moderate (downstream of road bridge). Slight (upstream of road bridge)
River Moriston - Decrease in water quality from site runoff 31, 50, 52, 54, 55, 56, 57, 58, 59, 60, 61, 62, 66, 68, 70, 81 Very High Temporary Negligible Neutral
Un-named burn - Decrease in water quality from site runoff 31, 50, 52, 55, 56, 57, 58, 59, 60, 61, 62, 70, 81 Medium Temporary Minor Slight
Allt Lagain Bhain - Restriction of flows 54 High Temporary Minor Slight
Allt Lagain Bhain - Disturbance of banks 53, 58, 64 High Temporary /permanent Minor, temporary Slight
Allt Lagain Bhain - Increased scour and subsequent deposition in burn 51 High Temporary/permanent Minor Slight
River Moriston - Increased deposition resulting from scour of Allt Lagain Bhain banks and bed and transport of sediments downstream to river 51 Medium Temporary/permanent Minor Slight
Allt Lagain Bhain flood area - Increased surface water runoff from working area leading to elevated watercourse flows 63 Low Temporary Negligible Neutral
River Moriston floodplain - Increased surface water runoff from working area leading to elevated watercourse flows 63 High Temporary Negligible Neutral
Table 10.5 Water Quality (Operation)
Potential Impact Mitigation no. Value/sensitivity of receptor Duration of impact Magnitude Significance
Allt Lagain Bhain - Decrease in water quality from site runoff 63 Very High Permanent Negligible Neutral
River Moriston - Decrease in water quality from site runoff 63 Very High Permanent Negligible Neutral
Small un-named burn - Decrease in water quality from site runoff 63 Medium Permanent Negligible Neutral
Allt Lagain Bhain - Spillage from vehicular collision resulting in pollution to burn 63 Very High Permanent Negligible Neutral
Allt Lagain Bhain -Changes in flood risk 70 Low Permanent Negligible Neutral
Changes in flow pathway at new crossing structure 70, 71 High Permanent Negligible beneficial Neutral
Allt Lagain Bhain - Changes in scour and deposition 71, 72 High Permanent Negligible Neutral
Allt Lagain Bhain -Change in planform of channel 71, 72 High Permanent Negligible beneficial Neutral
Table 10.6 Cumulative Effects
Potential Impact Mitigation no. Value/sensitivity of receptor Duration of impact Magnitude Significance
Potential for in-combination effects on ecology if A887 Allt na h-Innse Beag scheme is constructed at the same time as the proposed scheme. 95 Up to Very High Temporary Minor to Moderate Moderate if construction phases for both schemes are simultaneous.
Potential for in-combination effects on the water environment if A887 Allt na h-Innse Beag scheme is constructed at the same time as the proposed scheme. 95 Up to Very High Temporary Minor to Moderate Moderate if construction phases for both schemes are simultaneous.