GR 001/07 RIVER QUALITY 2005 Government Laboratory thie-scroodee-stoo yn Reiltys Ballakermeen Road, Douglas, Isle of Man, IM1 4BR. Telephone: (01624) 642250 E-mail:
[email protected] Website: www.gov.im/dlge/enviro/govlabs River Quality 2005 – Government Laboratory Executive Summary • This report presents a general assessment of river water quality, as regards biology, chemistry and nutrients for the period autumn 2000 to autumn 2005. • There has been a gradual improvement in both biological water quality (as assessed by invertebrate animal life) and chemical quality (dissolved oxygen, biochemical oxygen demand and ammonia) in the majority of rivers, with 99% classified as fair or above quality. However, there are regional differences and some individual rivers have deteriorated slightly. • In terms of the nutrients nitrate and phosphate, which are derived from artificial fertiliser, farm slurry and sewage effluent of rivers, 99% (nitrate) and 95% (phosphate) are classified as moderately low or better. While nitrate levels have shown little change, phosphate levels have increased slightly in some rivers. • The Island’s rivers are slightly better quality as regards biology and chemistry and much better as regards nitrates and phosphates, than in England, Wales and Northern Ireland. • Levels of metals and acidity originating from the Island’s geology, land use and disused mine workings may limit the potential invertebrate and fish populations in some rivers. • Generally, overall river quality is very good for the majority of the Island’s