3.5.1 The principle of conserving natural resources within the Mendip Hills AONB, using them in the most sustainable way, and enhancing their contribution to the needs of society is fundamental in the future management of the area. Water and soils are considered under this theme. Quarrying, woodland and forestry and farming are considered under Land Management theme (3.6)
3.5.2 Water management both quality and availability will benefit many ecosystem services, including soil quality, soil erosion and biodiversity.
3.5.3 The three reservoirs, Chew, Blagdon and Cheddar, supply water to 1.1 million people and businesses in the Bristol Water area and a 2nd Cheddar reservoir is proposed. Both Chew Valley Lake and Blagdon Lake are internationally important for wildlife. Chew and Blagdon are designated as Drinking Water Protected Areas with the catchments that drain to them and these catchments which drain to the lakes have also been identified as Safeguard Zones. The Environment Agency, Bristol Water, Natural England and other partners are developing Drinking Water Protected Area Safeguard Zone action plans to address the sources of nutrients in the lakes.
3.5.4 There is little or no risk of flooding within the hills as rivers flow underground in this limestone landscape but flooding has been experienced in the Chew Valley and Cheddar where the streams and river emerge. North and Mid Somerset and the Bristol Avon Catchment Flood Management Plans cover the AONB.
3.5.5 A large part of the AONB is within a Groundwater Source Protection Zone due to its contribution to the public water supply. Ground water quality is generally good overall although there is a need to reduce sources of diffuse agricultural pollution in to the groundwater and water courses and run-off and soil erosion into watercourses.
3.5.6 Grazing is restricted around the Chew and Blagdon reservoirs to prevent contamination. Parts of the AONB falls within the Somerset Levels and Moors, and the North Somerset Moors Sensitive Farming Priority Catchments where issues of nitrogen enrichment and phosphates and sedimentation have been identified affecting the quality of Chew Valley Lake. The area surrounding each of the reservoirs is designated a Nitrate Vulnerable Zone where farmers have to comply with EU regulations to reduce nitrate loss from agriculture.
3.5.7 Bristol Waters Metaldehyde Action Project includes Chew and Blagdon catchments provides updates and free advice to farmers to promote best practice on use of granular pesticides (inc slug pellets) and testing of soil, slurry and manure. Weekly water sampling in 2013 has shown consistently low levels of Metaldehyde.
3.5.8 Bristol Water continues to educate consumers about economical use of water. Constraints to limit or stop water being abstracted during low flow situations may become more frequent with a changing climate.
3.5.9 Whilst the run -off from land in this predominantly upland area is low, steep slopes in some areas can increase run- off rates locally and under extreme weather conditions have resulted in local flooding. It might be possible to reduce this by expanding and maintaining semi natural habitat particularly woodland on the steep slopes and boundary features e.g. walls and hedgerows.
3.5.10 As more land is now managed under arable there is an increased risk of soil movement where run- off risks soil deposition in water and cave systems.
3.5.11 Further demands on the public water supply through increases in population may exacerbate over abstraction. Demand increase from new development may be offset by increased efficiency in existing housing and industry.
Environment Agency Groundwater Protection zones, Nitrate Vulnerable Zone, Flood Management Plans
Natural England Sensitive Farming Catchments
Bristol Water Chew, Blagdon and Cheddar lakes