Series VII consists of reports, surveys, and studies produced by Pennsylvania Power & Light engineers, external organizations, or government agencies on various river systems, hydroelectric projects and developments, and water supply projects in central and eastern Pennsylvania. The majority of these documents focus on the Delaware River Basin, Susquehanna River, Lehigh River, Schuylkill River, and the Lackawanna River, as well as these rivers’ various tributaries. Subseries A, Floods and flood control, includes reports and studies on significant flooding problems along Pennsylvania’s major waterways, primarily the Susquehanna River and its drainage basin. Subseries B, Hydroelectric development and water supply projects, include reports on hydroelectric developments, reservoirs, and other water supply projects in Pennsylvania, largely east of the Allegheny River. This subseries also includes congressional documents on various river systems. Subseries C, Interstate Commission on the Delaware River Basin (INCODEL), is primarily composed of documents produced by the commission, including their activities, purpose, developments, projects, jurisdiction, and annual conference proceedings.