In making the decision to close 11 public libraries as of Dec. 31, the Nutter administration ignored a crucial piece of information: In many cases, public libraries are the de facto school libraries for children and teachers in Philadelphia.

Years of budget cuts have left many public city schools without libraries - a separate disgrace. That has meant sending students and classes to the local public library - including some of the 11 branches targeted for closure - during the school day.

Siobhan Reardon, executive director of the Free Library of Philadelphia, confirmed in an interview that this crucial detail wasn't part of the budgeting discussion. As such, that severely undermines what initially appeared to be a thorough analysis of which library branches to close.

In making its recommendations, city library officials looked at the proximity of one branch to another (the national standard is two miles apart), the population of areas served, total usage, facility size, and potential for expansion.

They also considered after-school uses, and whether those programs could be transferred to a local community or recreation center if a library branch was closed.

But they failed to consider the lack of libraries in the schools. And the fact that the public branch library often fills that void.

Reardon argues that detail wasn't considered because school libraries and their public counterparts have different missions. School libraries are part of the curriculum, and their staffs are integral members of teaching teams. Public libraries and their employees are not equipped to fully take on those tasks.

That's a fair point in a perfect world. But the reality is that since many Philadelphia schools lack libraries - and textbooks, but that's another story - public libraries often serve as the school's ad hoc library system.

Raising this point is not an attempt to ignore the city's budget crisis. Or the tough choices facing the Free Library administrators and other city agencies.

However, the issue - raised by City Council and the Friends of the Free Library - demonstrates the need to make informed budget decisions.

It also underscores the need for the Nutter administration to operate in public view and seek outside input - rather than meet in secret with Council and staff, as was done before the library closings and other budget cuts were announced.

At the very least, Mayor Nutter and Reardon should delay the decision to close the 11 libraries on Dec. 31.

They should use the time to determine the impact of any closings on local schoolchildren by talking to the Friends and other library advocates, to teachers and administrators at the schools near the 11 libraries, and to library staffs.

Perhaps during the delay the mayor - or Council, or the Friends - will find alternate plans on staffing or schedules that will help keep more libraries open. Perhaps some civic-minded foundations or other library boosters will offer financial support.

Or, perhaps, even armed with more information, the city will still make what Reardon calls the "heart-wrenching" decision to close the 11 library branches. Regrettable as that would be, at least it would be a fully informed decision.