Planning for sustainable development involves ensuring that development meets present needs without compromising the ability of future generations to enjoy full, healthy and satisfying lives. An important part of that task is to maintain and enhance the quality and diversity of the natural environment.

The policies for safeguarding the natural environment and open spaces are based on a four level approach. Areas and features are categorised as:

The term "natural" has to be considered in the context of a predominantly built-up area, within which most of the natural features might be more accurately described as "semi-natural" (or, in some cases, simply "not built on"). Features of this kind are likely to have higher value in an urban area than they may in a more rural or wild environment.

The multi-level approach, referred to above, has been adapted to suit an urban context from a method used by English Nature and from work carried out by that organisation for the City Council. It has also been adapted to take account of landscape qualities as well as nature conservation interest.

The qualities justifying the designation of "Critical Natural Assets" and "Basic Natural Stock" can be threatened by development elsewhere. These threats may come, more obviously, from development on land abutting the designated areas, but more distant development may also pose threats, such as visual intrusion; the severance of linkages between the City's open spaces and between those open spaces and the open countryside (undermining the ability of flora and fauna to regenerate); air and watercourse pollution; pollution of groundwater and impact on the water table; increased public access inflicting damage / by sheer weight of numbers, as well as irresponsible behaviour such as tipping and vandalism.

National planning policy and guidance is increasingly recognising that the onus may be placed upon applicants to assess and propose remedial measures to deal with the potential impact of their development proposals.   Consequently, where these abut, or the City Council is concerned that they would damage, Lincoln's "Critical Natural Assets", prospective developers will be expected to submit a written statement to:

The statements will then be taken into account in deciding planning applications. They will help the Council to consider the need for conditions attached to planning permissions and the negotiation of planning obligations.

In the case of Sites of Special Scientific Interest, the City Council is required to consult English Nature prior to the determination of an application which contains proposals "likely to affect" an SSSI - even if the application site is outside the designated area.