The governors of Delaware, New Jersey and Pennsylvania came away from a shipboard summit pledging to make the Delaware River cleaner while increasing opportunities for economic development.

The manner in which we collectively balance competing environmental and economic interests is fundamental to the future of our three states and the Delaware Valley region, the governors said in a statement after Monday's cruise.Govs. Michael Castle of Delaware, Thomas Kean of New Jersey and Robert

Casey of Pennsylvania promised to try to develop a comprehensive plan for the river and bay, a water system within 100 miles of 30 million people and overnight shipping to half the nation's industries.

The prime ports involved in the new study are Philadelphia, Wilmington, Del., and Camden and Salem, N.J.

The governors said past cooperative efforts failed because they sought to do too much while ignoring special state interests.

We plan to meet again around Sept. 1, but in the meantime our staffs will be working with the existing regional and bi-state public agencies and authorities, Gov. Kean said.

We hope that this meeting will serve as a catalyst for the many interests on the river to arrive at mutually agreeable changes that will benefit the people and the economy of the entire region, the statement said.

Gov. Casey, a Democrat, called the meeting historic, frank and constructive.

We all have a shared desire to make the Delaware the nation's most important river and to make its ports better by speaking with one voice, he said.

Gov. Casey said he will support legislative approval of a $34 million request by the Philadelphia Port Corp. for improvements to terminals over the next three years, while Gov. Kean and Gov. Castle, both Republicans, said they also will consider funding requests from their ports.

The governors charged their staffs with:

* Developing an appropriate mechanism to undertake projects designed to stimulate economic growth and produce new jobs for the region consistent with high environmental standards.

* Coordinating all programs to maintain and, if deemed commercially desirable and environmentally acceptable, to increase the depth of the river's channel.

* Cooperating in planning and assessment of all the transportation links along the Delaware River and bay.

* Joint formulation of a strategic development plan which will guide resource allocation into the next century.