The ecological or landscape qualities of these areas are so important, unusual or sensitive that:

Those areas currently regarded as Critical Natural Assets include areas which have been designated Sites of Special Scientific Interest and are, therefore, of national significance (Swanholme Lakes and Greetwell Quarry); Regionally Important Geological and Geomorphological Sites (Cathedral and Cross O'Cliff Old Quarries); and Sites of Importance for Nature Conservation which are of local value and significance (as assessed by the Lincolnshire Trust for Nature Conservation, in consultation with English Nature).

English Nature has recognised that sites which may not warrant statutory designation when assessed against national criteria may take on added significance in the context of a predominantly urban place like Lincoln.

With regard to landscape qualities, the sites classed as Critical Natural Assets include those which could not be lost to development without Lincoln losing a fundamental part of its special identity and environmental quality. Features like the Commons, Burton Cliff and the Witham Valley are critical because they allow us to see the natural canvas upon which the City has been painted by successive generations. Views associated with areas like these may themselves be of critical importance to Lincoln's character (e.g. the view of the Cathedral-crowned hillside across the West Common).

The Critical Natural Assets (including Sites of Special Scientific Interest) identified in this Local Plan are regarded as the absolute minimum which must be protected intact if Lincoln's ecological diversity and its essential landscape characteristics are to be preserved. Development will not normally be allowed in these areas unless it complies with a Management Plan, approved by the Local Planning Authority. Management Plans should be designed to protect the ecological, landscape, geological or other scientific interest and qualities of the area. Management Plans have already been approved for some areas, but they may need to be prepared and approved for others. In cases where the City Council owns or controls the land, it will normally be responsible for preparing the Management Plan. In other cases, land owners or developers may wish to prepare Management Plans, either in connection with development proposals or otherwise. The approval of the Management Plan by the Local Planning Authority will be necessary if a case is to be made for permitting development in accordance with such a Plan.

The sites currently regarded as Lincoln's Critical Natural Assets are identified on the Proposals Map and described in Appendix C, Schedule 1.