A set of maps showing proposed new boundaries for Maine’s 35 state Senate districts drew criticism Friday for lacking sufficient detail to show exactly how the borders would change next year if the Legislature approves either proposal.

Maine’s Apportionment Commission will hold a public hearing on the proposed congressional, state Senate and county commission maps Monday at 8:30 a.m. The commission’s deadline to submit proposed maps to the Legislature is Sept. 27.

Anna Kellar, executive director of the League of Women Voters, said Friday that the organization was disappointed that the granular detail needed to make informed comment was missing from the maps on the commission’s website.

“Voters in municipalities that are proposed to be split such as Portland and Scarborough are unable to determine which district they are proposed to be in,” said Kellar in a prepared statement. “We urge the Commission to immediately release shapefiles of proposed districts to meet its constitutional mandate to allow full public review of plans prior to submission. Maine taxpayers are funding the Commission’s work, and are entitled to a full review of the maps it has created.”

Emery Younger, a member of the commission staff, said later Friday that any map files the commission has available can be obtained by emailing a request to apcom@legislature.maine.gov.

The public is also encouraged to offer written comment via the same email address.

The commission released the maps proposed by Republican and Democratic members late Thursday afternoon, intending that they be used for public comment at Monday’s hearing. But beyond big adjustments that would shift entire cities from one district to another, the maps do not show residents what legislative district they will be in come 2022.

Among the communities facing changes because of the new population counts are Portland and its neighbors. The parties’ proposals for changing state Senate district boundaries would carve up the city of Portland in varying ways.

Under the Democratic proposals, Portland would share one senator with parts of South Portland and Westbrook and another with Chebeague Island, Cumberland, Falmouth, Long Island, Yarmouth and North Yarmouth, while a third district would be entirely within the city.

Under the Republican plan, Portland would have one Senate district entirely within city limits while a second would include parts of Portland, and all of Falmouth and Long Island. The city has two Senate districts now. Senate District 27 is entirely within the city and Senate District 28 includes parts of Portland and Westbrook.

The commission is operating under a constrained timeline for redrawing the districts, which is required under the state and U.S. Constitution every 10 years based on changes in population. A pandemic-induced delay in the release of federal census data has put the commission on a tight timeline to complete its work.

The state Supreme Judicial Court issued a ruling in July giving the commission 45 days to finish work once it had received the census population data. It needs to produce a recommendation for the Legislature to vote on by Sept. 27 to meet that deadline, but those proposals also must be vetted at a public hearing so voters and state and local election officials can weigh in.

Under state law and previous court rulings, the populations of state Senate districts must be mostly equal, but may deviate by 5 percent to minimize splitting cities, towns and counties among multiple districts.

The commission is made up of seven Republicans and seven Democrats and is chaired by former Maine Supreme Judicial Court Justice Donald Alexander. It usually has six months to complete its task is, but because the census data was delayed that was reduced to six weeks.

The release of competing maps Thursday is likely a starting point for ongoing negotiations. Any final plan would need two-thirds approval by the Maine Legislature. If the Legislature can’t reach that threshold, the new district boundaries will be determined by the state Supreme Judicial Court.

The commission is also redrawing the lines for county commission districts in all 16 counties.

In 2011, redistricting boundaries were settled by the Legislature, and in 2001, they were determined by the high court. The new districts will first come into play during a statewide primary election next June.