Will Rogers once observed that he was investing what little he had in land because there was only so much and no one was making any more of it. That is part of the reason public lands - the lands managed for the American people by the federal government and located primarily in the western United States - are so valuable as a public trust and as a legacy to future generations. And that is why the decisions of public land managers to sell or exchange these lands are among the most important they will ever make.

The Bureau of Land Management, with stewardship of more than 264 million acres - more than any other federal agency - completes 60 to 70 land exchanges every year. On average, these exchanges involve 150,000 acres of land each year at a value of about $50 million.Why do these exchanges occur? What does the public have to gain, and why are states, counties and private entities such willing partners?

One reason is that land exchanges enable the BLM to change the checkerboard pattern of federal, state and privately owned lands in the West into consolidated areas that are more easily managed. This decreases the costs of managing the lands and increases the efficiency with which they are managed.

But there are more important reasons. The exchanges allow the BLM to acquire the kind of land that is suited to public ownership: land with high conservation values as habitat for wildlife, including threatened or endangered species; land that offers recreational opportunities for the public; or land containing sensitive riparian areas that are critical to the health of streams, rivers and entire watersheds.

In turn, states, counties or private developers can obtain land that is better suited for local management or that will serve the development or expansion needs of growing communities.

Last summer, for example, the BLM's Canon City District acquired through an exchange the 1,272-acre VVN Ranch in Park County, Colo. The BLM did so with the help of the Rocky Mountain Elk Foundation, which purchased the property and held it until the land exchange could be completed. The ranch contains year-round elk habitat; significant scenic, recreation and wildlife resources; and three miles of wetland-riparian (stream-side) areas that were not previously available for public use. In return, 840 acres of land within 13 scattered parcels were transferred into private ownership.

The vast majority of land exchanges are so clearly logical and mutually beneficial that they are completed without protest or controversy. Sometimes, however, proposed land exchanges do become contentious. Appraisals can be subject to questions and criticism from those involved in a potential exchange or from outside parties. This makes the job of appraisers even more challenging.

Fortunately, our appraisers rely on an established and objective set of standards - such as comparable sales, access, existing improvements and mineral value - in estimating land values. In cases where there is a large discrepancy in the estimation of land values, the BLM may call in a third party or ask for a new appraisal.

Despite successes such as those I have described and hundreds more like them, we know that there is still room for improvement in our land-exchange process. We need to consider how the appraisal process might be revised, whether the BLM is applying consistent criteria in identifying potential land exchanges, how much discretion should be left to local BLM land managers, and what guidelines are needed when private developers and nonprofit conservation groups are involved.

To address these and other issues, the BLM is forming a National Exchange Team that will review the agency's land-exchange program and recommend ways to improve it. The team will also identify any pending exchanges that raise significant public policy concerns.

New data released recently by the Census Bureau for the period 1990 through 1996 demonstrate how fast the West is changing. It is the fastest-growing region of the country. Nine of the 10 fasting growing metropolitan areas in the United States are in the West, including places like Las Vegas, Boise, Phoenix and Provo.

And of course there is no mystery about why that is happening.

Open spaces, clean water and clean air are always high on the list of features that attract people and businesses. Proximity to mountains, lakes and rivers is also a key element in the choices people are making about where and how they will live.

Land exchanges are among the tools with which we address that obvious paradox: how to preserve the values that people find so appealing and yet accommodate the need for growth and development of Western communities.