Perdido River and Bay - Florida Department of Environmental ...

Water Quality Status Report: Perdido River and Bay
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than 45 inches to greater than 80 inches in a given year (U.S. Geological
Survey [USGS] Web Site: Calendar Year Stream Flow Statistics for Alabama).
The greatest amount of rainfall typically falls in July and August
(Schropp et al., 1991). Rumenik (1988) estimated that 25 inches of rainfall
per year near the Alabama border to almost 35 inches of rainfall per year
near the Gulf of Mexico was discharged as surface runoff. The surficial
geology, topography, and potential evapotranspiration of the basin are
factors that contribute to the amount of surface runoff.
This section delineates the basin’s hydrology, describes the movement
and management of water in the basin, briefly describes the major characteristics
of surface waters that influence water quality in the basin, and
describes surface water classifications and special designations. Figure 2.2
shows the locations of the largest waterbodies. More information about
individual waterbodies is contained in the planning unit discussion in
Chapter 3.
Hydrology
There are two components of the Perdido River and Bay Basin: the
Perdido River and Perdido Bay. The headwaters of the Perdido River are
near Bay Minette in Alabama. The river is formed by the confluence of
Fletcher and Perdido Creeks. The Perdido River Basin is located in eastern
Baldwin County and western Escambia County in Alabama and Escambia
County in Florida. About 810 square miles of the river basin are within
Alabama (SARPC, 1993). The Perdido River is 220 miles long with
96 miles within Florida (Florida Department of Natural Resources [DNR],
1989). The river ranges from 30 yards across in its upstream segments to
about 100 yards across near the mouth (Department, 2005). River flow is
rainfall driven and fluctuates greatly. Average discharge of the river at Barrineau
Park, as a 62-year average, was 1,174 cubic feet per second (USGS,
2006). Larger tributary watersheds are the River Styx, Blackwater River,
and Dyas Creek in Alabama and Brushy Creek, Boggy Creek, McDavid
Creek, and Jacks Branch in Florida. The River Styx and the Blackwater
River are the largest tributary watersheds. They enter the Perdido River
close to its mouth, and drainage from them provides substantial freshwater
discharge to both Perdido River and Perdido Bay (Schropp et al., 1991).
The Perdido River discharges into Perdido Bay about 15 miles west
of Pensacola. The bay is about 17 miles long and from 2 to 4 miles wide
(SARPC, 1993). The river and its tributaries are not the only sources of
water for the 28-square-mile bay. Bayou Marcus and Elevenmile Creek
in Florida and Soldier Creek and Palmetto Creek in Alabama along with
several smaller creeks add additional discharge into the bay.
Perdido Bay is a relatively shallow estuary, deeper on the Alabama
side of the bay relative to the Florida side. Average depth of Perdido Bay is
7 feet (USGS Web Site). Deeper portions of the bay (10 feet or deeper) are
located near the mouth of Perdido River and downstream of the U.S. 98
Bridge (Grubbs and Pittman, 1997).
The bay can be delineated into five different segments based on natural
constrictions and geographic features within the bay (Schropp et al., 1991).
The upper bay extends from the mouth of the Perdido River and