The nation’s water system has always been able to supply our needs…providing safe, reliable, cheap drinking water to hundreds of millions of people, cooling water for most of our electrical generation plants, and contributing to our nation’s hydropower, agricultural needs, wastewater management, flood control, and many other industries such as oil, gas, and mining.
But today that complex system is in distress due to many factors – a growing population, aging infrastructure, extreme weather patterns, and regulatory failures. One of these problems is affecting the Mississippi River as salt water from the Gulf of Mexico is migrating into the Mississippi River due to the river’s low water levels and flow rate. This was triggered by two years of summer’s blistering heat and low rainfall over major parts of the central U.S.
In July, the U.S. Army Corps of Engineers constructed an underwater barrier to create an artificial basin for the purpose of delaying the intrusion. This involved dredging sediment from the bottom of the river and piling it up to create what is known as a sill, which acts like a dam for the denser saltwater in the lower levels of the river. Since then, flow of water from the Gulf then topped the sill’s elevation necessitating additional work.
Plaquemines Parish, a parish in Louisiana with a population of over 20,000, is already feeling the impact. A look at their government website, plaqueminesparish.com reveals a header starting with “SALTWATER INTRUSION UPDATES…” The parish has a drinking water advisory in place from Empire Bridge to Venice on the west bank and Phoenix to Bohemia on the river’s east bank because of the high salt levels in the drinking water at their Boothville Water Treatment Plant.
If salt water continues to move upstream, additional communities along the river will be impacted including New Orleans. This could also affect several power plants located on the Mississippi in Louisiana: Big Cajun 1&2, Waterford Nuclear Plant, and River Bend Nuclear Plant.
Based on current estimates of the saltwater migration by the U.S. Army Corps of Engineers the saltwater is not likely to affect parishes upriver until mid-to late October, including St. Bernard, Orleans, and Jefferson Parishes. By late October, the salt water could reach West Jefferson.
According to Louisiana Governor, John Bel Edwards, the Mississippi River is forecast to reach “historic lows over the next several weeks”. The governor requested a federal emergency declaration for four parishes already affected or expected to be impacted over the next month. The declaration allows city agencies to prepare and respond to any impacts and allows the state and federal agencies to deploy resources as needed for a more streamlined process.
The U.S. Army Corps of Engineers is shipping in millions of gallons of fresh water daily to the lower Mississippi River near New Orleans to keep the New Orleans water supply salt free. In addition, to help mitigate the intrusion, the state and the Army Corps of Engineers are working to add twenty-five feet of height to the 1,500-foot-wide underwater sill created earlier in the year.
Typically, enough rainfall upstream keeps saltwater at bay but conditions over the past two summers and the current forecast do not show relief any time soon.