J.B. Converse Lake (Big Creek Lake) is a 3,600 acre tributary-storage reservoir in Mobile County in southwest Alabama.  It serves as the primary drinking water supply for the city of Mobile and is a local recreation spot for many reasons.  Converse Lake is a popular site for fishing and boating, even though swimming and water skiing are prohibited.  The warm Gulf climate attracts fishermen year round and supports a growing plant nursery in the watershed.

At present, the watershed is mostly rural and forested but as residential growth continues in the watershed the idea of non-point source pollution must be addressed.  Rapid and unmanaged human activities in the watershed can have a long term affect on water quality in the watershed.  Since the reservoir serves as the primary drinking supply for the city of Mobile, it is necessary that people understand what happens on the land has a direct impact on their water quality.

The Mobile Area Water and Sewer Service (MAWSS) manage Converse Lake and the E. Morgan Stickeny and Harry E. Myers Water Filtration Facilities.  Theses facilities treat raw water withdrawn by a pump station then delivers treated water to the  City of Mobile.  The area of land surrounding the reservoir is covered by a combination of evergreen and deciduous forest that is owned by MAWSS.  The remainder of the land primarily consists of pastures and dairy farms, forested woodlands, nurseries, pecan groves, and residential areas that use septic tanks for sewage disposal.   These land use activities contribute to non-point source pollution that influences the water quality in the reservoir.  Rainfall in the watershed causes runoff from the land that contributes to pollutants in the tributaries, which in turn end up in the reservoir.