Running a jail can be even more expensive than previously thought.

A study released Thursday by the New York-based nonprofit Vera Institute of Justice examined all costs associated with operating local lockups beyond budget line items.

The authors found services such as providing inmate health care, programming and funding employee benefits are sometimes covered by other county agencies.

Researcher Christian Henrichson says officials can't make smart reforms without appreciating the true, total cost of jailing.

The report surveyed 35 jail systems from 18 different states. It concludes reducing the inmate population is the only way to achieve real savings.

The report says that amid falling crime rates in Springfield, Massachusetts, the inmate population has likewise shrunk allowing the sheriff's department to save millions by closing housing units.