Consultant John Diez said the Ascension Parish Council reapportionment plan was hand-delivered July 5 in Washington, D.C., for U.S. Department of Justice review.

The council backed the plan last month, but narrowly because of divisions about a four-tenths of a percentage point change in the black population for one west bank council district.

Black leaders warned the council on June 29 that the council’s proposed map would be in violation of federal election laws, but after Diez predicted it would gain Justice Department approval, the council backed the plan.

The reapportionment plan submitted to Justice notes, Diez said in a subsequent interview, that declines in black population in District 1 are part of a long-term trend for that west bank district.

The Justice Department, which approves redistricting plans in the South and some other areas, must determine if the disputed change is significant enough to prevent the plan’s adoption.

The councilmen face election this fall. The Justice Department must approve the plan by Aug. 29 for it to apply in the Oct. 22 race.

A fairly small area, representing fewer than 200 people in the Aben community, is in contention. The nearly 40 percent population growth in Ascension between the 2000 and 2010 U.S. censuses forced significant changes to several districts in the new reapportionment plan, but the shifts have otherwise prompted little public debate.

Councilman Oliver Joseph had argued for an alternative map of council districts that boosted the minority percentage in his District 1 to 74 percent from the 73.6 percent in the map the council supported.

That plan would have added one census block to his district around Aben but would have altered Councilmen Kent Schexnaydre’s District 2 and Randy Clouatre’s District 6.

District 2 would have been left with a finger of territory along the west bank levee on Point Houmas so Schexnaydre’s district could snake around Aben to Donaldsonville.

Clouatre’s District 6, which already was being shifted north because District 1 had to gain population, would have been pushed slightly more north and out of St. Amant.

Under federal elections law, districts where minorities are the majority, so called minority-majority districts such as District 1, have benchmarks set for the percentage of minority voters within a district’s population.

Minority-majority districts are created to ensure minority voters are able to elect candidates of their choice.

Benchmarks for one census are based on the newly found minority population percentage in districts set by the prior decade’s reapportionment, Diez has said.

Benchmarks support the principle that minority voting influence should not be diluted unless it is unavoidable.

Both council plans, the one the council supported and the one Joseph promoted, lower benchmarks between 2000 and 2010 in Joseph’s District 1 and the other minority-majority district, Councilman Adrian Thompson’s District 3.

Under either plan, District 1 is falling from a benchmark of 76.1 percent.

Thompson’s district falls from a benchmark of 62.2 percent and loses slightly more than a percentage point under the council-backed plan, Diez has said.

Ascension’s black population grew faster than its white population in the past 10 years, but the benchmark reductions, Diez has said, reflect a tricky geographical split by the Mississippi River with the most rapid growth in one area around Dutchtown and Prairieville.

So it was last month that two sides debated the significance of four-tenths of a percentage point.

Diez told the council it would be hard to argue four-tenths of a percent could prevent District 1 minority voters from selecting their preferred candidate.

Cedric Floyd, a Jefferson Parish School Board member and a demographer, told the council that under voting rights law, when the council lowers minority benchmarks, it has the burden of showing a less retrogressive plan could not be reasonably drawn.

In fact, Floyd argued, the council had that alternative in Joseph’s plan.

David J. Mitchell covers Ascension Parish government for The Advocate. His email address is dmitchell@theadvocate.com.