(CNN) -- The first women to serve on U.S. Navy submarines are expected to be on the job by fall of 2011, Navy officials said Thursday, ushering in a policy change to what has been an elite service open only to men since the start of the modern Navy's submarine program.

While Defense Secretary Robert Gates announced the change last month, the Navy had to wait for Congress to review and approve the policy change over a 30-day period which ended at midnight Thursday morning.

The official announcement came later Thursday from the commander of Submarine Group 10, Rear Adm. Barry Bruner, during a news conference at the Navy submarine base at Kings Bay, Georgia.

The first women chosen for the program will be selected by the Navy among upcoming graduates from the Naval Academy, the collegiate Reserves Officer Training Corps -- also known as ROTC -- and officer candidate schools.

Those women will go through the intensive 15-month submarine officer training program, which includes nuclear power school, submarine training, and the Submarine Officer Basic Course.

The Navy will implement the policy change by assigning three female officers to eight different crews of guided-missile attack and ballistic-missile submarines. The assignments involve two submarines on the East Coast and two on the West Coast, according to Navy officials.

Smaller, fast-attack submarines are considered to be too small to accommodate the necessary infrastructure change in living quarters that is possible on the larger subs, Navy officials explained.

Integrating female officers into the submarine squadrons is the first phase of the policy change. Including female enlisted sailors into the crews will take place in a second phase in the coming years, the officials said.

Women joined the crews of the Navy's surface ships in 1994, but officials had previously cited limited privacy and the cost of reconfiguring the vessels in arguing against their joining sub crews.

The change in policy was recommended by the top naval officer, Adm. Gary Roughead; the secretary of the Navy, Ray Mabus; and Gates. No Navy leaders opposed the plan, officials said.

"The young women that have come up to me since we announced our intention to change the policy have such great enthusiasm," Roughead said in a statement Thursday.

"There are extremely capable women in the Navy who have the talent and desire to succeed in the submarine force," Mabus added in the same statement.

Women make up 15 percent of the active duty Navy: 52,446 of 330,700 sailors in the service, according to Navy statistics.

Female sailors still cannot serve in the elite SEAL program, because those are considered frontline combat unit positions. Similar regulations in the other branches of the military also prevent women from serving in combat positions.