An ongoing situation in Louisiana that has generated a lot of news coverage is introducing the term “saltwater intrusion” to many people. It also highlights the potential impact of more familiar challenges facing the water sector – climate change, drought and source water protection.
Prolonged drought conditions as the result of climate change reduced Mississippi River flows.
The drought page on DrinkTap states, “Global climate change may cause some areas to receive less rain while others receive more. In addition, climate change may impact the intensity of rainfall, so that more rain falls over a shorter period. Climate change could also impact drought by increasing temperature, which could increase demand and evaporation.”
In the Louisiana case, the reduction in water and flow strength from the Mississippi River is allowing saltwater from the Gulf of Mexico to flow up the river and create a saltwater intrusion. The upstream movement of the intrusion is threatening drinking water sources for many cities in Louisiana, including New Orleans.
The Louisiana Department of Health says healthy people are unlikely to be impacted by increased salt levels in the water, but it might affect pregnant people or those with kidney disease or high blood pressure. The U.S. Environmental Protection Agency requires utilities to issue an advisory if salt content exceeds 250 parts per million, which is when the water will taste salty, but before it would pose a threat to human health.
The intrusion triggered a series of emergency declarations, including a federal emergency declared by U.S. President Joe Biden which mobilized support and response efforts. The Army Corps of Engineers (ACE) quickly constructed a sill in the riverbed to break up the saltwater intrusion. ACE has built underwater dams in the Mississippi River to block saltwater intrusions in 1999, 2012, 2022 and then again, this year.
The good news is there are plans to build a 48-inch pipeline to pump fresh water from upstream to dilute the saltwater before it is expected to reach the Carrollton water treatment plant, which services the city of New Orleans. Additionally, there are proactive measures in place to distribute bottled water to New Orleans public schools should the city’s drinking water supply become unsafe.
Photo by Chris Granger/Nola.com