Early settlers in New Orleans found the Lake Pontchartrain clam shells could be used for roads and driveways. Growing up the service alley at my Lakeview home would get regular dumping of fresh shells and often other things would be found in them like arrow heads and even bullets.
I never tasted the Lake Clams, Rangia Cuneata, but the local Native Americans did a lot as we find shell middens all over the area from them leaving behind the white calcium rich sun bleached shells. I am told they are boiled and the water changed to clean them out and remove a harsh taste. They are considered too small for commercial eateries but locals still dig and boil them especially in Virginia and Mexico. A local dish is made called, "arroz a la tumbada", a rice and seafood soup.
Growing up these small clams benefited the local economy as many material trucks would carry them for construction. That was until the dreding was banned and now we use gravel which is heavier aand more costly.
Lake Pontchartrain Clam Diggers T-Shirt
by figstreetstudio
From USGS at http://pubs.usgs.gov/of/2002/of02-206/env-issues/clam-abundance.html :
"From 1933 to 1990 Rangia cuneata clam shells were harvested in Lake Pontchartrain. According to 1980's estimates, these shells had a gross annual value of $34 million and were used for the construction of roadways, parking lots, and levees and in the production of cement ( USACE , 1987). Forty-four percent of the Lake was opened to shell dredging. Dredging operations were prohibited around the shoreline, bridges and gas pipelines. Shell dredgers used a large suction device to draw up shells, sediment and water, creating trenches 1.5-2 m wide and 0.5-1 m deep. The shells were removed and the sediment and water were discharged back into the Lake ( USACE , 1987). This slurry produced a localized increase in turbidity. Despite the economic value of the shell mining industry, dredging in Lake Pontchartrain was banned in an effort to improve water quality."
Information on Lake from: http://library.thinkquest.org/CR0214360/
"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."
I don't know what one dredge might generate to dirty up the lake, but a government owned dredge could give the lake parishes cheap material to provide cheaper services to the public.
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