back cove

portland peninsula

portland tidal gauge

  • Portland Peninsula

    The city of Portland lies on a curved peninsula that extends into the waters of Casco Bay. To the north of the downtown area is the Back Cove, a mile-wide tidal basin and estuary. Over the past two centuries the perimeter of the cove has become smaller as the shoreline of the peninsula has grown larger from in-filling.


    The above map indicates two notable sites on the peninsula where the impact of high tides can easily be observed. Somerset Lagoon and Knudsen Pond are located in Bayside and East Bayside neighborhoods respectively. The names are fictional but the transient bodies of water are factual. They appear during the highest tides, and then quickly disappear as the tides recede. It is easy to mistake the flooding for excess rainwater, but close observation reveals that the inundation occurs at regular intervals and is related to cycles of the tides.


    Flooding is also a regular occurrence along Commercial Street in the Old Port. The Portland Tide Gauge, which was installed in 1912, is located on the Maine State Pier just off Commercial Street. Data from the gauge informed the research related to this project and is an important resource for studying sea level change, particularly as it relates to the Portland waterfront.


    Hand-Painted Map: MollyMaps