1) Scottish Water (2006). Public Water Supplies in Scotland: Water Resources Survey 2004-2005.
2) Drinking Water Quality Regulator for Scotland (2006). 'Drinking Water Quality in Scotland 2005'.
3) Poor and seriously polluted categories should be unaffected by the length of river classified each year. Any changes to these figures generally reflect a change in quality. Changes to the length of rivers classified as excellent, good and fair are mainly due to the overall increase in length classified, so such figures are not included.
4) Scottish Environment Protection Agency (2003). SEPA Annual Report 2003-2004.
5) Scottish Environment Protection Agency (2006) National Water Classification 2005.
6) Data is expressed as mg N/l. To convert to mg NO 3/l (nitrate), multiply by 62/14.
7) A fixed set of 192 locations, based on nitrate directive locations, was used. The percentages may not sum to 100% due to rounding.
8) This applies to most European rivers though for some rivers up to 1 mg N/l is reported. European Environment Agency, 'Indicator Fact Sheet'. '(WEU02) Nitrogen and phosphorus in rivers'.
9) In Aberdeen, Moray, Banff and Buchan, Strathmore, Fife Lothians and Borders, and Lower Nithsdale.
10) Under The Designation of Nitrate Vulnerable Zones (Scotland) Regulations 2002 and The Designation of Nitrate Vulnerable Zones (Scotland) (No. 2) Regulations 2002 and EC Nitrates Directive (91/676/ EEC) Annex 1A(3).
11) Soluble reactive phosphorus was measured. To convert to µg PO 4/l (orthophosphate), multiply by 95/31.
12) In 1993 and 1994 one phosphate site made no recordings so 191 sites were used for these years.
13) From 2002 onwards discharge rates are being calculated over the calendar year.
14) Matter other than sewage or trade effluent.
15) Scottish Environment Protection Agency (2003). Corporate Plan April 2003-March 2004.