The District agency that oversees the well-being of hundreds of children in the city's foster-care system is changing the way it monitors children who live in Maryland, consolidating services offered by seven agencies under a single provider.

About 400 children are wards of the District while living with foster families across the state line. Some live there because relatives have taken them in. Others have special needs that Maryland families are able to accommodate.

But because the Child and Family Services Agency is a District agency with no authority in Maryland, these children — more than 40 percent of D.C. wards in foster care — are monitored by seven private companies that have CFSA contracts.

CFSA Director Brenda Donald said bringing children under a single agency will ensure consistency and quality of care.

"We want to make sure children are getting the best of what we have to offer," she said.

The CFSA is not making the change to save money but the agency does expect cost savings, agency spokeswoman Rachel Molly Joseph said in an email. How much is unclear, because the contract still has to be negotiated.

The agency also has placed children with families in Virginia, but they will not be affected by the change.

Donald said the rates the District pays foster families are the highest in the country. A CFSA spokeswoman said rates are high because of the city's cost of living and requirements under LaShawn A. v. Gray, a decades-old class-action lawsuit under which the D.C. foster-care system is monitored by a federal judge.

Private agencies submitted their proposals to the CFSA in May. The new agency will be in place by January, Donald said.

The change does not sit well with the seven contractors that will lose millions of dollars annually after existing contracts are severed.

Tonya Jackson Smallwood, president of Family Matters of Greater Washington, which works with 60 D.C. foster children in Maryland, said her agency's contract with the CFSA is worth $3.2 million annually.

"Every provider in this field is very surprised by it, and none of us believe this is in the best interests of the children we serve," she said.

The restructuring will require foster families to be re-licensed by the agency the CFSA chooses. Some providers and advocates fear that some families might not want to go through that process and that foster children would lose their homes as a result.

The changes also will be felt in the District, where the foster parents of 77 children, some with special needs, are under the supervision of the same private agencies that license and oversee children in Maryland.

The CFSA was reaching out to affected foster parents to "provide a smooth transition," spokeswoman Mindy Good said in an email.

Aaron C. Davis contributed to this report.