It makes sense to add 72 spaces to the parking facility that will be next to the renovated Lawrence Public Library, but the funding mechanism for that parking raises some questions.

Parking continues to be at a premium in many parts of downtown, and it will cost less to add 72 spaces during the library renovation than in a separate project later on.

However, the plan to pay for the parking by assessing all property owners in a pretty widely drawn footprint of downtown doesn’t seem exactly fair. The proposed benefit district for the assessment stretches far beyond the Massachusetts Street retail and restaurant properties and takes in residences, churches and other businesses (including the World Company). North of Eighth Street, the district reaches from Kentucky to Rhode Island streets. South of Eighth to South Park, it narrows but still includes all the properties that face on Vermont and New Hampshire streets.

That means it includes all of Watkins Park, on which the city will pay its own assessment, but it also includes a number of churches, Watkins Museum, the Lawrence Arts Center and residences, including the Hobb-Taylor Lofts.

They call it a “benefit district,” because everyone being assessed within that district supposedly derives some “benefit,” from the improvement. In this case, the most obvious benefit is to the city and city residents who visit the new library or the Outdoor Aquatic Center. Next on the list would be retail businesses, restaurants and bars whose customers and employees would use those parking spaces.

After that, it gets more fuzzy. Maybe the churches or residents in the district will derive some benefit, but is that benefit greater than what a taxpayer in some other part of the community would enjoy? And if that’s the case, shouldn’t providing parking for the library or pool or downtown in general be an expense that’s borne by the community as a whole rather than concentrated on downtown property owners?

If a district could be drawn narrowly enough to include just businesses and entities that would directly benefit from the additional parking, benefit district financing would make sense, but city officials say they can’t exclude properties based on their use and they’ve done the best they can to define the right geographic boundaries.

Protesting this plan would require a petition that covers 50 percent of the property owners and 50 percent of the property in the district. That will be a tall order, considering that city-owned property represents about 35 percent of the district’s total area.

So a protest petition is unlikely, but that doesn’t necessarily mean a benefit district is the best and fairest way to pay for this project. Lawrence city commissioners should reconsider this approach before approving the resolution on Tuesday’s agenda to move forward on this plan.