The relationship between NEPA and CSD/CSS is confusing but both aim at selecting the best alternative, both are intended to provide timely information for effective decision making,a nd both provide the interdisciplinary framework for considering the positive and negative impacts of the proposed action.

Management Structure:
Establish Environmental Review Process

Because NEPA is a national law that applies to all federal agency actions, it is almost always implemented through a series of regulations promulgated by each federal agency and in many cases each state DOT. Despite this national law, and the common aim to provide the agency with a defensible decision process, each of these agency regulations is different from the others in its particulars. In all NEPA projects, though, it is necessary to identify the lead and cooperating agencies as well as the type of review required. It may not be possible to determine if an EIS, EA, or CE is appropriate during the first step of the process, although in many cases the lead agencies are able to make the decision even at this early point. The earlier the determination can be made, the better, because it affects the design of the public and agency outreach programs as well as a variety of data gathering efforts.

If the project does not require either federal funding, a federal agency permit, or other approval action, and is therefore not subject to NEPA regulations, the environmental review process will likely be guided by local, regional, or state environmental regulations as well as response to stakeholder issues and concerns. Some agencies choose to follow NEPA even if it is not required to ensure that if conditions change, and a federal action is later triggered by the project, there is no need for "back tracking" to accommodate federal requirements.

In addition to understanding the relationship of the project to NEPA, it is also important to determine the applicability of other regulations that can affect the development, evaluation, and selection of alternatives, and the ultimate implementability of the project. Such regulations might include local, regional, or state laws that control land use; restrain urban growth; protect against adverse impacts to specific lands, species, or other resources; require a public vote to approve certain types of projects; or require a public vote to approve funding for particular projects.

Knowledge of the regulatory framework in which the project will be developed at the outset of project development helps to avoid surprises that cause delays and rework at later stages of the process. The NEPA process is clearly intended to operate as an umbrella approach so that all related environmental laws, regulations, and policies are considered in a coordinated fashion during decision making.