The Beach Outfalls Challenge is a public prize competition sponsored by the Mississippi Department of Environmental Quality (MDEQ). MORE

Outfalls & the Mississippi Coastal Streams

Tuesday, January 24th, 2017

When you say “beach outfall” along the Mississippi Gulf Coast, most people think about the closed pipes that run along the beach. But there is a second type of outfall that exists in the Mississippi coastal landscape – open concrete culverts. These open concrete culverts are the drainage points for the Mississippi coastal streams, the concrete drainage network, and the roadside ditches that run throughout Hancock, Harrison, and Jackson Counties (Figure 1).

Figure 1: Mississippi’s coastal streams empty into the Mississippi Sound via open concrete culverts.

Similarly to the closed pipes, the open concrete culverts provide very little treatment to the water entering the Mississippi Sound, especially when draining the concrete drainage network in Hancock County. However, in the areas where the open concrete culverts drain the coastal streams and the roadside ditches, the natural streambed provides ecosystem service benefits like water quality improvement. Unlike the concrete drainage network, the natural streambeds are lined with gravel, rocks, and leaf litter. These natural materials slow the water as it moves downstream. Slow moving water allows for natural process to improve the quality of water flowing through the streams and ditches.

When water is allowed to be in direct contact with the streambed, excess nutrients and bacteria can be converted to less harmful, more biologically beneficial compounds (Figure 2).

Figure 2: Natural streams provide significant ecosystem service benefits to the community.

Potential solutions to the Beach Outfalls Challenge can occur in-stream as well as on the beach. For more information on the technical guidelines for in-stream solutions, please refer to page 9 of the Rules document.

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Check out this video to learn more about how the coastal streams are connected to the beach outfalls: