Great Hill Pond is a 76-acre body of water in Portland, CT. It is an artificial lake fed by the Great Hill Pond Brook. It has a 10-foot dike at the south end. Its only public access is a carry-in boat launch with minimal parking. On average the pond is 5.5 feet deep and reaches a maximum of 9 feet in a small area to the south. During our survey in August 2006, 19 aquatic species were collected, including the invasive species fanwort (Cabomba caroliniana). At this time, the beach was closed due to high levels of fecal coliform, and it was noted that all of the houses use septic systems.

Starting from the boat launch in the middle of the eastern shore and moving north, there are sizeable patches of eelgrass (Vallisneria americana) and the invasive fanwort. The northeast cove has a large amount of fanwort, both by itself and underneath white water lily (Nymphaea odorata). There are also patches of watershield (Brasenia schreberi), yellow water lily (Nuphar variegata), and white water lily close to the shore. Also in this cove are small amounts of golden hedge-hyssop (Gratiola aurea), arrowhead (Sagittaria species), western waterweed (Elodea nuttallii), needle spikerush (Eleocharis acicularis), ribbon-leaf pondweed (Potamogeton epihydrus), and floating bladderwort (Utricularia radiata).

Along the northern shore is abundant eelgrass with some humped bladderwort (Utricularia gibba) and ribbon-leaf pondweed. Further west is a large area with all of the floating species as well as a small area of fanwort, ribbon-leaf pondweed, and eelgrass. 

The sheltered, brook-fed cove to the northwest is completely filled with vegetation. The mouth of the brook has arrowhead, yellow water lily, white waterlily, and watershield. The mouth of the cove has a large area of spotted pondweed (Potamogeton pulcher) intermingled with fanwort. 

Moving down the western shore, there are several small patches of white water lily, as well as abundant eelgrass and a single patch of fanwort. The western shore also contains very small patches of all species listed below. This mix continues down around the southeastern shore.

The western-most inlet contains more fanwort as well as a very diverse, dense mixture of all of the lake’s plants. Recreation is only compromised in the two northernmost coves, where large patches of floating species may interfere with boating enjoyment.