Tarnishing the Jewel: Damming the Pascagoula’s Tributaries

The Pascagoula River is Mississippi’s ecological jewel. Most of the river’s main tributaries are contained within state borders, and its health reflects the health of the streams that flow through the state’s southeastern quarter. It was ranked with other rivers in the northern hemisphere on their degree of channel and flow alteration by the journal, “Science” in a 1994 article: “Fragmentation and Flow Regulation of River Systems in the Northern Third of the World” . The article produced the stunning statistic that the Pascagoula is only river of its size class in the U.S. (not counting Alaska) without a dam on its main channel. Among all the large rivers in the lower 48 states, the Pascagoula stands alone. However, plans for creating dams on Big Cedar Creek to form two recreational lakes are currently in an Army Corps of Engineers scoping process. A meeting in Lucedale Mississippi on January 24th 5-8 pm at the Senior Citizen Building at 7102 Hwy 198 East is the only chance for public input on this project. Local government sponsors: the George County Board of Supervisors and the Pat Harrison Waterway District are now pitching the creation of two lakes to supply water to the Pascagoula River during droughts. If damming happens, it will chip away at the special nature of the Pascagoula system. The industries that supposedly need this water haven’t requested new reservoirs. It seems the Port of Pascagoula and the Pascagoula Chevron Refinery downstream are being used by local government to justify building recreational lakes. George County government has wanted a recreational lake for at least 15 years. This is a new twist on an old desire.The 1994 ranking was great, but it wasn’t news to people that the Pascagoula is special. Land conservation efforts over nearly 40 years along the lower 1/3 of the river have connected a broad patchwork of protected floodplain swamps, forested wetlands and marshes to help maintain water quality and habitat along the main stem of the Pascagoula in George and Jackson Counties in southeast Mississippi. The Nature Conservancy and the State of Mississippi negotiated the purchase of the Upper and Lower Pascagoula Wildlife Management Areas from a lumber company in 1974 and public and private efforts have continued to add parcels of conservation land along this river corridor. The river has been studied by research scientists for years including the threatened species that live in and along it. The Yellow blotched sawback turtle and the Gulf sturgeon inhabit the river and are both protected by the Endangered Species Act. Black bears inhabit the river’s forested wetlands and Gopher tortoises can be found in upland areas with sandy soil near the river and its tributaries.Another species of special concern, striped bass, has been restocked in the Pascagoula and Pearl Rivers and has been the subject of ecological study. One study spanning 1997-1999 used striped bass fitted with radio tags to track their movements and pinpoint the habitats they used. This research revealed thermal refuges or “cool spots” in the Pascagoula River where adult fish would congregate in summer months. Three such places were found, but the best one was in the Pascagoula River at the mouth of Big Cedar Creek. This thermal refuge was used by the tagged fish over two years to beat the summer heat. Fish are cold-blooded and regulate body-temperature by seeking out water with a favorable temperature range, compatible with their metabolic requirements.That study, “Location of Thermal Refuge for Striped Bass in the Pascagoula River” was published in the Journal of the Mississippi Academy of Sciences in 2002 by Mississippi State University professor Don Jackson and his fisheries students. It offered management recommendations to protect the striped bass from overfishing while they congregated in summer in the cool water where Big Cedar Creek meets the Pascagoula River. The Creek has cool water because of the many springs that feed groundwater to it as base-flow. Knowing that Big Cedar has cool water and that fish use it to survive in the summer is just one facet of the Pascagoula River’s special status.Lakes and their dams reliably degrade the physical function of streams in two ways: they disrupt the downstream flow of sand, gravel and sediment and change the temperature of water released through dam outfalls to downstream channels. Dams are sediment traps and heat exporters. Lakes have heated surface waters in the summer and the outfall of the lower proposed dam into Big Cedar Creek is close enough to the main channel of the Pascagoula River that it would likely raise the temperature of the summer cool spot in the Pascagoula at the Creek’s mouth. Just like that – the river’s best thermal refuge disappears. The striped bass won’t congregate at the mouth of Big Cedar Creek if the water is just as warm as any other place in the river.The loss of the cool spot at the mouth of Big Cedar Creek is only one of many alterations that would accompany dam building. We can expect a degradation of the physical and biological quality of Big Cedar Creek, its associated wetlands, and to this local section of the Pascagoula River. Dams disrupt fish migration and movement too, so there will be changes to the distribution of species that call Cedar Creek home. Expect lakes built on porous, sandy soils to lose water to underground seepage. Expect significant year-round surface evaporation of water from lakes, in both wet and dry years. Lakes may store water for droughts, but in doing so they lose plenty of it through evaporation. Along with the creation of recreational lakes, promoted under the guise of “helping” the flow of the Pascagoula in future droughts, we expect a loss of some of the characteristics that make the Pascagoula River and its tributaries so special now. Andrew Whitehurst is GRN’s Water Program Director and works on Mississippi Wetland and Water Issues.

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