USGS/Jeff Marion

Figure 1. The National Park Service is developing a commercial services plan at Haleakala National Park (Hawaii) that will include user capacity indicators and standards. This scene depicts a popular park activity: enjoying sunrise from the summit of Haleakala volcano. Indicators and standards will help park staff manage heavy-use areas and commercial services such as bike and horseback-riding tours.

User capacity, previously referred to as visitor capacity or carrying capacity, came to the forefront of public land planning in the 1970s. Concern over rising visitation in parks and the accompanying impacts on resources and visitor experiences led the National Park Service to focus increasing attention on user capacity. In 1992 the National Park Service began developing a visitor experience and resource protection (VERP) framework to address user capacities in the National Park System (Hof et al. 1994). The VERP framework has subsequently been applied in national parks across the country, including Acadia (Maine), Isle Royale (Michigan), Arches (Utah), Yosemite (California), and Haleakala (Hawaii) (fig. 1, above).

Although many people think of user capacity as a maximum number of people (i.e., a limit) for a given area, the concept is much more complex. Research has shown that user capacity cannot be measured simply as a number of people because impacts to desired resource conditions and visitor experiences are often related to a variety of factors that include not only the number of people but also types of activities, where people go, what kind of impacts they leave behind, what type of resources are in the area, and the level of management presence. In an attempt to acknowledge these variables, the National Park Service defines user capacity as the types and levels of public use that can be accommodated while sustaining the desired resource and social conditions that complement the purpose of the park.

Research has shown that user capacity cannot be measured simply as a number of people.

The premise behind VERP, and almost all of the other user-capacity management approaches (e.g., limits of acceptable change [LAC], visitor impact management [VIM], and visitor activities management process [VAMP]), is that with any use comes some level of impact that must be accepted. Furthermore, the public land management agency is responsible for determining what level of impact is acceptable and what actions are needed to keep impacts within acceptable limits. As such, user capacity frameworks incorporate the following key elements:

1. Identifying desired resource and social conditions for each area (management zone) of the park
2. Setting resource and social indicators (specific, measurable variables that will be monitored) and standards (a management decision about the minimum acceptable conditions for the indicators) for each zone
3. Monitoring the indicators to measure success in achieving and maintaining the desired resource conditions and visitor experiences
4. Taking management action when resource or social conditions are “out of standard” or are deteriorating and likely to become “out of standard”

The public land management agency is responsible for determining what level of impact is acceptable and what actions are needed to keep impacts within acceptable limits.

Indicators and standards for user capacity may be part of many different types of plans including general management plans, comprehensive conservation plans, resource management plans, river plans (fig. 2), wilderness plans, trail plans, and visitor use management plans.