Gov. Harry Hughes sent the General Assembly yesterday a $5.9 million supplementary budget with extra money for Baltimore, welfare recipients and some social programs, but nothing for Montgomery County.

Included in the governor's fiscal 1986 supplement are requests for $1.6 million in additional police aid to Baltimore, $1.3 million for indigent adults who receive General Public Assistance -- a $5 a month increase above the extra $10 Hughes included in his original budget -- $1 million for additional community based treatment of the mentally ill and $240,000 for an evaluation of the troubled State Police personnel system.

However, the document contains no relief for Montgomery County, which still is seeking funds for up-county road and school projects. Whatever slim chance the county had of getting money within the supplement evaporated when the Senate Budget Committee approved a $35 million across-the-board budget cut that was vehemently opposed by Hughes and subsequently overturned by the full Senate.

Nonetheless, Senate leaders are still holding out some hope the county could achieve some of its goals in the capital budget and through a change in the state's road project timetable.

"We're trying to do something, but nothing is concrete now," said Senate President Melvin A. Steinberg (D-Baltimore County), suggesting that Montgomery would receive help only if other large jurisdictions such as Prince George's and Baltimore counties also win some projects.