SAN DIEGO -- Numbers obtained by 10News revealed a shrinking reality when it comes to undeveloped land in San Diego County.

In September, Shelley Federhart bought a new home in the Del Sur development in Black Mountain Ranch.

"We love it here," said Federhart. "We love the feeling of the community. There are so many events. The parks are great."

Others are also feeling the love. About 850 homes have already been built. Despite a slow real estate market, developers say there are signs of improvement. They say a total of 3,000 new homes will be up by 2018.

The development stands on 4,600 acres of a shrinking resource: undeveloped land.

According to the research group Equinox Center, 83 percent of all developable land in the county has been used up. That number will grow to almost 90 percent by 2030 and 95 percent by 2050.

Most of the untouched land is in parts of North County, parts of the East County, and it could now be disappearing at a quicker rate.

In the last year, while the region's population increased at less than one percent, there was a 1.7 percent increase in the amount of land set aside to build homes.

"For the first time in several years, the amount of land developed is outpacing our population growth," said Ann Tartre, the executive director of the Equinox Center.

The region's population is expected to grow by more than 650,000 in the next decades.

"As more land is used up, we're going to have to think about whether we're going to develop in a different way," said Tartre.

One of those ways is denser development that is closer to transit.

At Del Sur, 600 condo and apartment units will be included in the community because the market demands it. The development also includes 13 parks.

"If you have a variety of homes, that allows many to buy into other the master plan," said Bill Ostrem, the developer of the Del Sur community.

As for the region's master plan, expect a growing list of questions, thanks to that shrinking reality.

10News and the Equinox Center have partnered to examine quality of life issues facing the region. If you would like more on the issue of land use, visit www.equinoxcenter.org.