SPRINGFIELD — Too many inmates and too few guards have led to dangerous conditions at the state’s second oldest prison, according to a report issued Tuesday.

The report by the John Howard Association said the Menard Correctional Center in Chester has had an “alarming” number of staff and inmate assaults this year, primarily because the prison has the worst inmate-to-staff ratio of all of Illinois’ maximum-security facilities.

The Chicago-based prison watchdog group said there have been 14 staff assaults since Jan. 1, including one in the prison library that sent a correctional officer to a St. Louis hospital with facial fractures.

“Inadequate security not only jeopardizes the physical safety of inmates and staff, but it also undermines rehabilitation efforts and creates a psychologically damaging environment for everyone who lives and works behind the prison wall,” the report noted.

The organization has been exposing problems within Illinois prisons and juvenile facilities in recent years through a series of facility visits. Along with raising questions about overcrowding, the group has found a number of problems within the state’s fleet of 27 adult facilities, including inmates being housed in potentially unsuitable settings at the Vandalia minimum-security facility and a shortage of underwear at the medium-security Taylorville facility.

The group says the situation could lead to a lawsuit, similar to one that has forced California to release thousands of inmates to relieve overcrowding.

Most of the Department of Corrections’ recent inmate management problems stem from a surge in the prisoner population, which began rising after Gov. Pat Quinn stopped an early inmate release program over concerns that violence-prone prisoners were being let out on the street. Current reports show the state is holding 49,066 inmates in a system designed to house 33,703 inmates.

Menard has 3,621 inmates in a 133-year-old facility designed to hold less than 3,100 prisoners. It holds more convicted murderers — more than 2,000 — than any other prison in the state.

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The association’s report, based on a June visit to Menard, found that prison administrators placed the prison on lockdown for roughly half of the year, meaning the inmates spend 21 to 22 hours per day locked in their cells. That practice, the group said, has led to a tense and more violent atmosphere within the facility.

“Like other Illinois facilities, Menard suffers from systemic overcrowding, understaffing, and limited access to medical and psychiatric treatment, rehabilitative services, education, and jobs for inmates.” the report noted.

A spokeswoman for the Illinois Department of Corrections did not return messages Tuesday.