The following is taken from Craven's History of Horsham.
On June 26 1946 a formal protest was made by the Horsham Citizens Committee against the building of the Warrington dam and reservoir, which would have inundated approximately 5,000 acres, including a large part of Horsham Township. Over 450 homes would have been destroyed and about 2,000 persons dispossessed. The reservoir was to supply water for the city of Philadelphia.
The land to be flooded was primarily rich farm land. In 1946 production in Horsham was surpassed in Pennsylvania only by Lancaster and York Counties. The loss of vast historical and cultural resources was protested by the Director of the Philadelphia Museum of Art, and the Philadelphia Chapter, Pennsylvania Society of Architects of the American Institute of Architecture. The commanding officers of the Willow Grove Naval Air Station felt that the proximity of a large body of water would limit and possibly force the shutdown of the pilot training program at the Air Station. The economic loss to the state and particularly to Montgomery and Bucks Counties was noted.
Concerned citizens enlisted the services of a lawyer, whose fee was paid from solicited funds, and through the combined efforts of the residents of Horsham and the groups noted above, who held that a suitable alternative could be found, the proposed dam and reservoir were never built.
HPHA has maps and drawings showing the area that would have been affected by this dam in our document collection.