Saco Bay (Maine) - Sand Movement and Erosion

Sand Movement and Erosion

The United States Army Corps of Engineers (USACOE) initially thought that the beach sand was coming from an underwater glacial deposit. Thus when in 1866 they were called in to protect the navigable channel of the Saco river they built rock jettys on the both sides of the mouth of the Saco river to protect the channel from sand. The north jetty was extended in 1897, 1930 and 1938, and raised at various dates through 1969. The primary source of sediment for the beaches is the Saco river. Longshore drift is dominantly to the north along the shore. About 1960 another jetty was built on the south (Pine Point) side of the mouth of the Scarborough River to protect it from sand. It was not until 1992 that the USACOE acknowledged that there is no source of sand nourishment in the area. Thus, erosion is worst at Camp Ellis in Saco at the south end of the system where the Saco jetty prevents sand from coming ashore naturally while Pine Point is growing both from the sand coming out of the Saco river and from sand eroding from Cape Ellis and other parts of the bay to its south.

Much of the inner shore of the bay is within the town of Old Orchard Beach, Maine's largest resort beach community. The geology of the larger Gulf of Maine means that warm waters coming up the Atlantic Coast are kept far offshore, while the inshore waters are flowing from the north to the south, fed by the Labrador Current that originates from the glaciers of Greenland, making most Maine coastal waters very cold, especially to the east. The combination of Saco Bay's western location, the inland waters of the Saco river, and the bay's local flow from the south to the north make it the warmest water for swimming in Maine, although summer water temperatures regularly dip into the 50s (Fahrenheit).