Planning for Hillside Development

ROBERT B. OLSHANSKY, AICP

TABLE OF CONTENTS

Planning for Hillside Development

Hillsides pose unique problems for the construction and maintenance of human settlements. They are prone to natural hazards, and they topographically constrain the design of developments. For these reasons, hillside lands often remain vacant long after adjacent valley floors are urbanized. Despite the constraints, they are attractive places to live because of the views and because of the sense of being close to nature. But excessive hillside development can diminish the very views, idyllic surroundings, and wildlife habitats that residents value.

Local governments regulate hillside development for a variety of reasons. These include the protection of:

• lives and property from landslides and fires;
• natural resources, such as water supply;
• environmental features and systems, such as river corridors, wildlife habitat, and natural vegetation;
• aesthetic or scenic quality; and
• access for residents, visitors, and public service providers.

In practice, these goals are often intertwined. Because of the variety of geologic settings for hillside development and because of the different purposes that may lead a local government to develop hillside regulations, there is no "best" or "model" set of regulations that can be recommended. Indeed, many tradeoffs and choices must be made when making decisions about hillside development policies. It is not enough to hope that a hillside ordinance borrowed from a neighboring community will solve all one’s problems. Does your community want to safely provide a large number of housing units? Or would you rather limit hillside development to low-density, upscale custom homes? Do you want to preserve only the appearance of the hills? Or would you rather emphasize the natural environment and wildlife habitat? Do you prefer wider roads for fire safety purposes or narrower roads that minimize slope disturbance? Would you rather have dense native vegetation for aesthetic and environmental purposes, or irrigated landscaping for fire safety? The list of choices could go on.

Hillside regulation generally takes one of three philosophical approaches. The first approach is to use site design and engineering techniques to virtually eliminate all hazards to public safety. This is often accomplished by means of complete reconstruction of slopes to established engineering standards. The second approach is to perform selective grading, drainage improvements, and vegetation clearance in order to achieve public safety purposes while still retaining some valuable natural features of hillsides. The third approach is to prohibit hillside development because of the natural resource value of hillsides and because of mistrust of the dependability of engineering solutions. Communities need to choose carefully among these approaches; allowing intensive hillside development can permanently change the character of a community. In practice, most plans and ordinances contain elements of all three approaches. This can be problematic because the rationales underlying these approaches can conflict with each other. Still, many communities have found that it is possible, though not easy, to selectively combine parts of all three.

This report argues for being more careful in designing hillside plans and ordinances, and being more explicit about the goals, values, and tradeoffs inherent in those plans and ordinances. There are at least two reasons for this. The first is to help planners to be able to craft regulations that more precisely meet the purposes of the community and its leaders. The second is to present more consistent, legally defensible regulations to potential developers. Given the scrutiny that is being applied to land-use regulations by private property rights advocates and the courts, local governments need to pay special attention to the reasons for their ordinances and in designing the solutions to fit the problems. A more comprehensive consideration of the full range of issues presented in the list of questions above would help to improve the hillside ordinances in many communities.

This report draws upon documents gathered from 190 local governments in 22 states to offer up a variety of answers to a community"s questions about how to achieve its goals in regulating hillside development. Appendix C offers excerpts from the hillside regulations and guidelines of 13 jurisdictions and one nonprofit agency that should prove useful to those attempting to compose or revise their hillside regulations.