WATER QUALITY AND POLLUTION
The sea has been used as a dump for waste from people's activities for a long time. This includes waste dumped directly, like sewage and industrial waste, and indirectly through pollutants released into rivers and contaminated run-off from farmland. In recent years, however, there has been increasing concern over the affects of pollution from these sources.
A variety of impacts upon water quality are present in the coastal and marine waters of the Moray Firth that result mainly from human activities within the river catchment, tidal and coastal waters of the Moray Firth.
Both treated and untreated sewage is discharged both directly into the sea and indirectly via the freshwater catchment of the Moray Firth. In general terms, the influence of those discharges on primary production in open waters is slight, the main influence being the reduction of benthic diversity in the area of deposition around outfalls. Sewage may result in microbial contamination, the accumulation of persistent toxic materials, organic enrichment and increased Biological Oxygen Demand causing a variety of effects on the marine ecosystem.
Improvements to many systems around the Firth have been completed over the past few years, including providing full sewage treatment for the first time at Avoch, Nairn, and Brora. At Ardersier the old discharges along the foreshore have been eliminated. The discharge from Fort George has been taken into the system and is fully treated at a new treatment plant before being returned to the sea. Improvements to the Golspie treatment system are now under construction.
The biggest change we are likely to see in the inner Moray Firth is from the recently completed wastewater treatment works at Allanfearn which treats all sewage from Inverness to high modern-day standards. Until a few years ago raw sewage from Inverness went straight into the sea at the Longman - only over the last few years was sewage screened before going into the sea. The Allanfearn plant provides biological treatment and ultra violet disinfection, and represents a major step forward in improving chemical and biological water quality in the area.
Industries discharging effluent into the Moray Firth catchment area and coastal waters are mainly oil related operations, whisky distilling, woollen goods manufacturing, sand and gravel quarrying, fish farming and fish processing. Discharges from these may cause localised pollution problems, the character and scale of which will vary with the nature and amount of discharge.
Pesticides and fertilisers can enter the marine environment via land run-off. This is more difficult to control and, although water courses can be monitored, land run-off itself is largely unmonitored in the Moray Firth but believed to contribute insignificantly to increased toxin or nutrient levels in the marine environment.
Water Qualities of the different areas of the Moray Firth
Latest results from monitoring have classified the Dornoch, Cromarty, Beauly and Inverness Firths as all of 'good' water quality. The only exception was in the Inverness Firth at Longman Point where the water quality was 'Fair/poor'. However, as this was due to raw sewage discharges from Inverness, we are likely to see big changes now that the wastewater treatment works at Allanfearn has been completed.
Ref: Scottish Environmental Protection Agency www.sepa.org.uk