Lake Pontchartrain started forming about 5,000 years ago when North American glacier melts caused the Mississippi River to swell and shift eastward. The river began depositing its sediment into the Gulf of Mexico, which started to form a delta. The delta would slowly grow eastward, and over 2,000 years it would separate this body of water from the gulf to form Lake Pontchartrain. Its Native American name was Okwata, meaning "wide water", we know it as Lake Pontchartrain because the Native Americans led the Frenchman Pierre La Moyne, Sieur d'Iberville through the areas wetlands. He admired Okwata so much he renamed it Lake Pontchartrain after the French Minister of the Marine.
Before the late 1960s, the Lake's shores were prime spots for picnickers and swimmers. But because of the bad pollution in the lake, the shores were closed for swimming and picnicking. Some causes of pollution are urban runoff, and poorly treated and untreated sewage. Some things you might not consider pollution, like saltwater intrusion, or natural forces, like hurricanes also affect the eco-system of the lake. Over the last sixty years there has been a loss of more than 65,000 thousand acres of wetlands. If you think about it, that's more than 1,000 acres a year. One thing that that played a significant role in this is shell dredging (banned in 1991), a process in which Rangia clams (they're those little white seashells) are scraped off the lake bottom and used on roads and driveways. It has literally turned the lake bottom upside down.
The Lake Pontchartrain Basin is made up of 16 parishes (counties) that range from rural to highly urban and support 1.5 million people. The Basin is made up of many different kinds of wetland habitats.
The LPA, the Lake Pontchartrain Area is the area that encompasses the lake. In this area, the draining and filling of wetlands to accommodate the urbanization of the north shore and south shore has greatly affected the water quality of the lake by introducing excessive nutrients and pollutants. Nutrient overloading, which comes from drainage canals or river watersheds, can sometimes lead to algae blooms in the lake.