The House of Representatives is expected to approve today an Omnibus Parks Bill containing $43 million for the C&O Canal, Manassas Battlefield Park and other projects in the District, Virginia, Maryland and West Virginia.

The bill, which now goes to the Senate, is a spending authorization. The actual appropriation of funds will be considered later.

Among features of the bill is money for a foot bridge over the Potomac River at Harper's Ferry National Historical Park. A committee report noted that the National Park Service had considered several options to provide visitors and hikers "a safe means to cross the river."

The committee report leaves the final decision on how to provide a foot crossing to the Park Service, but calls for "this access to be provided at an early date."

Another of the 14 regional projects is a controversial proposal by Rep. Herbert E. Harris (D-Va.) to expand the Manassas National Battlefield Park. The plan, which earlier drew heated opposition from officials and residents in Prince William County, had been passed once by the House but has been bottled up in the Senate by Sens. William L. Scott and Harry F. Byrd Jr.

The Manassas plan, authorizing $8.5 million to expand the 3,000-acre park by about 1,700 acres, appeared to be dead until it was attached yesterday to the billion-dollar House Bill.

Now it appears certain to go to a House-Senate conference to settle differences between the version of the bill expected to clear the House today and the Senate version likely in late summer. Its fate then is likely to be decided on the Senate floor after the two houses agree on a compromise, House and Senate sources said.

Other, noncontroversial items are:

The Chesapeake and Ohio Canal National Historic Park, $6 million for acquisition of 600 acres in western Maryland and West Virginia and $5 million for development, restoration and repair of the two path, locks and historic structures. The land is part of the right of way of the Western Maryland Railway Co.

Harper's Ferry National Historic Park, $5.7 million to construct a visitor contact facility and transportation terminal, restore and preserve historic buildings and build the pedestrian crossing.

Frederick Douglass Home in Washington, $937,000 to complete construction of the visitor center, parking, walks and landscaping.

Piscataway Park and Marshall Hall in Prince George's and Charles counties, $2 million for planning site rehabilitation and development and restoration.

George Washington Birthplace National Monument, $2.8 million to add 1,065 acres clearly visible from the main visitor area and threatened by development.

Monocacy National Battlefield in Maryland $3.5 million to extend the park boundary by buying 587 acres.

Petersburg National Battlefield in Virginia, $2.2 million to buy the historic Eppes Manor.

Harris' opportunity to add the Manassas Battlefield Park bill came as a result of Rep. Phillip Burton's (D-Calif.) packaging of a wide assortment of authorizations that usually are moved as individual bills. By putting them all together, the defeat of the entire package becomes unlikely.

Senate sources said yesterday that the House bill would be trimmed considerably before a compromise conference.

Burton said yesterday of the Manassas bill, "We don't consider it permissible to hold it ransom. If the Senate had passed it in some form we could have gone to conference. They didn't and now we will (make sure it does). We're going to see that the matter is given a review on its merits."

In sending the bill to the House, Harris suggested a series of changes to the Senate to reduce the hostility with which the bill has been met in Prince William County.

Harris' maneuver was greeted by hostility on the part of Prince William County Board of Supervisors chairman, Donald White, who said, "It's the typical treatment we have received. He may think it's helping his candidacy (for reelection), but I don't think it will."