Park officials have announced improvements to county trails:

* The county Park Authority will dedicate the Potomac River Gorge interpretive trail at 10 a.m. Saturday at Riverbend Park in Great Falls.

The 21/2-mile trail, with 14 explanatory signs along the Potomac River shoreline, runs between Riverbend Park and Great Falls Park.

The trail is part of the 15-mile Potomac Gorge area that extends from Great Falls to Theodore Roosevelt Island in the District. It was financed by the Park Authority and with matching funds from the Chesapeake Bay Gateways Network.

Refreshments will be available in the visitor center before the ceremony. Those who want to walk a portion of the trail to Great Falls Park can take a shuttle bus back to Riverbend Park.

* Tomorrow and Saturday at 8 a.m., Park Authority staff members and volunteers will be building and installing two fiberglass pedestrian bridges in the Difficult Run Stream Valley.

The smaller of the bridges is 28 feet long and will cross a tributary of Difficult Run just south of the Dulles Access and Toll Road. The bridge is funded by a contribution to the Fairfax County Park Foundation from Craig R. Stevens and his family. The second bridge is 37 feet long and will cross a tributary south of Vale Road. The two bridges will be assembled on-site.