It’s true that wherever you stand in Alabama, you are not far from a stream or river. Alabama’s wet climate provides the water for these streams while the surrounding lands guide surface water and groundwater to them year round. These streams wander the landscape in many directions, but all eventually join rivers that flow to the coast. Thus, it is also true that wherever you stand in Alabama you are connected to the great Gulf of Mexico to the south.
The waters that drain from Oak Mountain State Park (OMSP) all reach the Alabama River though the paths they take are varied. Given its large size and high elevations, numerous small streams drain the park and join larger creeks in nearby valleys. Several of these have been dammed to create the park’s four reservoirs. Peavine Branch runs across the top of Double Oak Mountain, cascades down the southeastern slopes, and joins Peavine Creek in the valley below. Peavine Creek runs northwest to join Buck Creek in nearby Pelham, AL. Buck Creek then flows west through Helena, AL, and soon joins the Cahaba River. Oak Mountain and the lakes on the north side of the mountain discharge into a stream that is also part of the headwaters of Buck Creek.
While all these streams belong to the Cahaba watershed, one corner of the park belongs to the Coosa River watershed. In the northeast corner of the park the southeastern slopes of Double Oak Mountain and the area near Shackleford Gap drain south to Cooper Branch. These waters then flow southeast to join the North Fork of Yellowleaf Creek which passes through Chelsea, AL. The North Fork continues southeast and joins Yellowleaf Creek which flows into Lay Lake on the Coosa River at Wilsonville, AL.
By way of these streams, OMSP contributes to two of the most famous watersheds in all of North America. The Cahaba River is the only undammed river of its size in Alabama and hosts more fish species per linear mile than any other river in North America. It is also the source for about 25% of Alabama’s drinking water, much of that going to the Birmingham metropolitan area. The Cahaba’s watershed receives waters from the southwestern portion of Alabama’s Valley and Ridge physiographic region, flows southwest to cross the Fall Line (the boundary of the uplands and coastal plain) near Centerville, AL, and then turns southward to join the Alabama River near Selma, AL.
The Coosa River is the largest river in the Alabama River watershed, draining a corner of southeastern Tennessee, northwest Georgia, and much of northeastern Alabama. Just south of the Fall Line and east of Montgomery the Coosa joins the Tallapoosa to form the Alabama River. The Coosa River is also famous for its biodiversity, once supporting nearly 300 species of fishes, mussels, snails and crayfishes. Unfortunately, the Coosa is known for being the site of the largest historic mass extinction event on the continent. Damming of the river during the twentieth century led to the extinction of nearly 40 species of freshwater snails and mussels.
After reaching the Alabama River, the waters that started their seaward journey within Oak Mountain State Park flow southwest and merge with the Tombigbee River to form the Mobile River about 35 miles north of Mobile. The last leg of the journey takes these rivers through the Mobile River Delta, one of the largest, wildest river deltas in the U.S. After reaching Mobile Bay, Double Oak Mountain’s waters mingle with the saltwater tides and eventually join the Gulf of Mexico. Forests supply watersheds with clean water, and OMSP contributes to the health of the area’s streams and rivers and ultimately the waters of the northern Gulf of Mexico.