Swan Lake and to the mouth of Port Bay. The bay's maximum depth is , and in contrast to the Laguna Madre (approximately 80 miles down the coast to the south), is not hypersaline. The Mission and Aransas Rivers are the main freshwater sources: small rivers with deep banks that carve through a landscape lined with hardwood trees. Their inflows increase during significant rainfall and reach their seasonal highs during the autumn. These rivers have not been dammed and thus flow free. At both mouths, marshes covering several square miles stretch from the confluences with Copano Bay and forming several saline lakes. Ecosystem Copano Bay serves as a nursery for shrimp, which attracts a large number of redfish. Abundant collections of black drum, flounder and trout, can also be found in the bay. Oysters grow in large numbers to form elongated reefs "oriented perpendicular to tidal flow" in the estuary. The reefs provide habitat for fish and sustenance for a wide variety of birds including the black-bellied whistling-duck, black-necked stilt, brown pelican, gull-billed tern, reddish egret, roseate spoonbill, seaside sparrow, white-faced ibis and the whooping crane. The dominant species of gastropod in the bay is Eulimastoma harbisonae. In 2003, the United States Department of the Interior granted $574,000 to Texas Parks and Wildlife to purchase over of prime birding habitat at Egery Flats and the mouth of the Aransas River, to prevent further development. Industry Oil and natural gas wells are located both onshore and offshore of Copano Bay. Three oil and natural gas fields are found on the bay, including the Copano Bay Oil and Gas Field, just west of Holiday Beach, the South Copano Bay Oil Field, just offshore from Bayside, and the West Fulton Beach Gas and Oil Field to the west of the Live Oak peninsula. In 1997, a pipeline owned by Koch Industries burst in the marsh in Refugio County, two miles (3 km) west of Copano Bay near the Aransas River, spilling 1,000 gallons of oil over a area. The oil did not seep into Copano Bay, preventing a minor environmental disaster. Copano Bay is off limits to shrimping due to its designation as a nursery bay. References Bays of Texas Bodies of water of Aransas County, Texas Bodies of water of Refugio County, Texas