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Key Scottish Environment Statistics 2004
Public Water Supplies, Yield and Demand:
1981-1982 to 2002-2003
Average volume of water (Megalitres/day)
| 1981-82 | 1990-91 | 1995-96 | 2000-01 | 2001-02 | 2002-03 |
Yield from developed water resources | 3,246 | 3,486 | 3,501 | 3,564 | 3,563 | 3,564 |
Daily demand from public supplies | 2,262 | 2,301 | 2,322 | 2,401 | 2,408 | 2,387 |
For sustainable management of water resources, it is essential to meet consumers' demand and standards, whilst maintaining aquatic ecosystem health. Abstraction of water has impacts on geology, habitats, wildlife, biodiversity, and recreational use of water resources. To prevent low flow levels downstream, minimum compensation flows need to be discharged at all times. Compensation flows are specified in the Water Orders made under the Water (Scotland) Act 1980.
Demand for water in Scotland has increased by 6% since 1981-1982, although yield from developed resources (representing the potential water available) is still greater than demand. For 2002-2003, daily demand includes an estimated 47% lost through leakage.
Water demand comes from unmetered and metered potable water, and small amounts of non-potable water. Unmetered demand (domestic use, small industries, public use, etc.) accounted for 81% of daily demand in 2002-2003, compared with 70% in 1981-1982. In contrast, metered demand decreased from 28% to 19% of daily demand. The decrease in metered demand may represent industry using less water to reduce water supply and waste water charges.
SOURCE: SCOTTISH EXECUTIVE WATER SERVICES DIVISION 1
Drinking Water Quality: 1991-2002
| 1991 | 1995 | 1999 | 2000 | 2001 | 2002 |
Number of samples taken (000's) | 227 | 231 | 143 | 152 | 173 | 148 |
Percentage failure for all coliforms | 7.0 | 2.6 | 1.5 | 1.1 | 0.9 | 1.3 |
Percentage failure for faecal coliforms | 3.0 | 1.0 | 0.3 | 0.2 | 0.1 | 0.2 |
The coliform group of organisms is present in large numbers in the gut of all warm-blooded animals and therefore widely distributed in the environment. Their presence in tap water indicates a breach in the integrity of the water supply system.
The 1990 Water Supply (Water Quality) (Scotland) Regulations set strict standards for compliance and the success rate varies across Scotland. The major centres of population are served by water treatment works, which are generally well equipped to achieve the standards set. Infrequent minor and low level failures with little implication occur at these works. Rural areas not served by treatment works can have water of variable quality.
Between 1991 and 2002 the percentage failure for all coliforms fell from 7% to 1.3% and the percentage failure for faecal coliforms fell from 3% to 0.2%. However, there was a small rise in the failure rates between 2001 and 2002.
The standard set by the Water Supply Regulations, for 95% of samples to be free of all coliforms, has been met every year since 1992. However, the strict standard of zero faecal coliforms in all samples has not yet been achieved, with 0.2% of samples failing this test in 2002.
SOURCE: SCOTTISH EXECUTIVE WATER SERVICES DIVISION 2
River Water Quality: 1999-2003
Length (kilometres)
Classification 3 | 1999 | 2000 | 2001 | 2002 | 2003 |
Poor | 1,078 | 854 R | 929 | 903 | 751 |
Seriously polluted | 91 | 73 R | 83 | 56 | 53 |
Unclassified | - | 12,816 R | 11,960 | 7,999 | 5,903 |
Total length of network | 25,382 | 25,455 R | 25,511 | 25,445 | 25,436 |
Low standards of river water quality may threaten the aquatic environment, drinking water quality and recreational water use. Sewage, industry, urban development and agriculture are some of the factors that may affect river water quality.
The Scottish Environment Protection Agency (SEPA) has established a Digitised River Network (DRN) to classify about 25,000km of the approximately 100,000km of rivers and burns in Scotland. The DRN comprises those watercourses draining a catchment of 10km2 or more. Rivers are classified as excellent, good, fair, poor or seriously polluted according to measures of chemical, biological, nutrient and aesthetic quality. Between 2000 and 2003 the length of 'unclassified' river fell by more than a half.
Between 1999 and 2003, the length of poor and seriously polluted rivers in Scotland has fallen by 366km 4. The improvement of the indicator between 2002 and 2003 may have been assisted by the dry weather of 2003, which resulted in reduced volumes of potentially polluting run-off to rivers. SEPA has set a target of a reduction of 351km in poor and seriously polluted rivers for the period 1999-2006. 5 Poor biological and nutrient quality are the most frequent reasons for classifying rivers as poor or seriously polluted.
SOURCE: SCOTTISH ENVIRONMENT PROTECTION AGENCY
Nitrate Concentrations in Rivers: 1993-2003
Percentage of sites within band 6
| 1993 | 1995 | 2000 | 2001 | 2002 | 2003 |
>=7.5 mg/l N | 5.7 | 6.3 | 5.7 | 4.2 | 4.7 | 2.6 |
>2.5 to 7.5 mg/l N | 14.1 | 13.5 | 14.1 | 16.1 | 14.6 | 16.7 |
0.75 to <2.5 mg/l N | 33.3 | 35.4 | 32.3 | 32.3 | 34.4 | 31.8 |
0.3 to <0.75 mg/l N | 13.5 | 13.0 | 16.7 | 15.6 | 12.5 | 14.1 |
<0.3 mg/l N | 33.3 | 31.8 | 31.3 | 31.8 | 33.9 | 34.9 |
The enrichment of waters by nutrients, such as nitrates and phosphates, can damage the aquatic environment through the accelerated growth of algae and other plant life. The rapid growth and subsequent decay of plant organisms depletes oxygen levels, this may have harmful effects upon fish and other aquatic life. This process is known as eutrophication.
High nitrate levels have a greater impact on marine and coastal waters than freshwater, although nitrates in freshwater will eventually reach the sea. The main source of nitrates in freshwater is run-off from agricultural land.
Concentrations of nitrate below 0.3 mg N/l are considered to be natural or background levels; 7 around one-third of the sites met this classification in 2003. Between 1993 and 2003 the percentage of sites with average nitrate concentrations >=7.5 mg/l N fluctuated, reaching a peak of 7.8% in 1998 and falling to a minimum of 2.6% in 2003. The figure for 2003 may have been affected by the dry weather conditions resulting in less run-off that year.
Regulations have been made designating 14% of the area of Scotland 8 as Nitrate Vulnerable Zones (NVZs). 9 In NVZs mandatory rules on farming practices aim to reduce nitrate water pollution from agricultural sources.
SOURCE: SCOTTISH ENVIRONMENT PROTECTION AGENCY
Orthophosphate Concentrations in Rivers:10
1993-2003
Percentage of sites within band 6,11
Band (mg P/l) Average | 1993 | 1995 | 2000 | 2001 | 2002 | 2003 |
>=500 g/l P | 1.0 | 3.6 | 0.5 | 1.0 | 0.0 | 0.5 |
250 to <500 g/l P | 4.2 | 4.7 | 3.6 | 2.6 | 2.1 | 3.1 |
125 to <250 g/l P | 7.3 | 8.9 | 10.4 | 12.5 | 5.7 | 5.7 |
50 to <125 g/l P | 23.6 | 21.4 | 19.8 | 20.3 | 17.7 | 16.7 |
25 to <50 g/l P | 20.4 | 18.2 | 19.3 | 18.8 | 19.8 | 18.2 |
<25 g/l P | 43.5 | 43.2 | 46.4 | 44.8 | 54.7 | 55.7 |
Excess orthophosphate in freshwaters can lead to eutrophication. The main sources of orthophosphate are outputs from sewage treatment works and diffuse pollution from agriculture.
Between 1993 and 2001 there was some fluctuation, but little overall change, in the distribution of mean orthophosphate concentrations. Over this period the percentage of sites with mean concentrations <25g/l P averaged 45% and the percentage of sites >=125g/l P averaged 16%. In 2002 and 2003 the percentage of sites with mean concentrations <25 g/l P increased to an average of 55% and the percentage of sites >=125g/l P fell to an average of 9%. This reduction in orthophosphate concentrations is in part due to the installation of orthophosphate removal facilities in sewage treatment works.
Under the Urban Waste Water Treatment Directive (UWWTD) (91/271/EEC), the Ythan Estuary, Dean Water, South Calder Water, River Almond, the lower part of the River Don and their respective catchments are all designated sensitive areas. Discharges into waters that have been designated as sensitive require additional treatment to remove nutrients.
SOURCE: SCOTTISH ENVIRONMENT PROTECTION AGENCY
Effluent Compliance with Discharge Consents: 1996-1997 to 2002
Samples complying with relevant standards (Percentage)
Type of discharge consent | 96-97 | 97-98 | 98-99 | 99-00 | 00-01 | 01-02 | 2002 12 |
Trade effluent | 74 | 83 | 78 | 80 | 85 | 81 | 84 |
Public sewage | 78 | 82 | 86 | 86 | 89 | 88 | 89 |
Private sewage | 51 | 64 | 75 | 70 | 78 | 81 | 72 |
Other discharges 13 | 87 | 89 | 91 | 93 | 93 | 87 | 92 |
All discharges | 73 | 80 | 82 | 82 | 86 | 85 | 85 |
Under the Control of Pollution Act (1974) it is an offence to cause or knowingly permit discharge of poisonous, noxious or polluting substances to controlled waters in Scotland. Discharges of sewage and trade effluent into controlled waters, including all coastal and inland waters may, however, be made under a discharge consent authorised by the Scottish Environment Protection Agency (SEPA). Authorisations contain conditions on both the quality and quantity of effluent permitted. SEPA control these discharges through licensing and monitoring.
Point source sewage effluent is currently the most important source of pollution affecting tidal waters in Scotland.
The overall compliance rate increased from 73% in 1996-1997 to 85% in 2002. Compliance rates for trade effluent and public sewage discharges have risen by 10% and 11% respectively since 1996-1997. Private sewage discharges show a 21% increase in compliance rates since 1996-1997 but have fallen from a peak of 81% in 2001-2002. SEPA has set a target of 95% compliance for licences issued under the Control of Pollution Act by 2003-2004. 14
SOURCE: SCOTTISH ENVIRONMENT PROTECTION AGENCY
Compliance with the EC Bathing Water Directive (76/160/EEC): 1988-2003
| 1988 | 1995 | 2000 | 2001 | 2002 | 2003 |
Mandatory standard compliance (%) | 52 | 83 | 84 | 84 | 91 | 95 |
Guideline standard (%) | 9 | 22 | 41 | 41 | 41 | 67 |
Failure to comply (%) | 48 | 17 | 16 | 16 | 9 | 5 |
Number of identified coastal bathing waters 15,16 | 23 | 23 | 58 | 58 | 58 | 58 |
High quality bathing waters are important for a wide variety of interests and support Scotland's tourism industry. Monitoring the quality of these waters provides an indication of the health risks of bathing from both direct and diffuse discharges of effluents containing faecal contaminants.
EC Bathing Water Directive (76/160/EEC) sets out two quality standards - the 'mandatory' standard, and the stricter 'guideline' standard. Member states should comply with the mandatory standard and aim to comply with the guideline standard.
In 2003, 95% of identified coastal bathing waters achieved the mandatory standard, and 67% also complied with the guideline standard. The 2003 compliance rates are the highest on record.
It is important to note that the weather is thought to affect compliance, with wet weather often contributing to poorer results and, conversely, drier, hotter weather associated with better results.
SOURCE: SCOTTISH ENVIRONMENT PROTECTION AGENCY
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