Impact of land use on concentrations of ions, Total Dissolved Solids, and Total Suspended Solids in East Baton Rouge Parish

Douglas Carlson Louisiana Geological Survey, Louisiana State University, Baton Rouge, Louisiana, 70803-001

Past studies in the Baton Rouge, Louisiana area considered stream water quality during storm events but ignored water quality during low flow periods. This study includes determination of stream water quality during low flow time periods for 9 watersheds in East Baton Rouge Parish, Louisiana. One watershed Dawson Creek includes water quality over a decade, long to possibly be impact by an evolving watershed become more developed through time.   These samples were collected during dry-low flow periods as indicated by water levels at USGS stream gaging sites for each stream. Analytical analysis for ions was completed using colorimeters and gravimetric analysis for TDS and TSS. Land use appears to impact concentrations of ions, TDS and TSS in variety of ways during periods of low flow. The two most rural watersheds, that are mainly underdeveloped, have higher concentrations of Fe and Mn. By contrast the three most urban watersheds, that are mainly commercial, industrial or residential, have higher concentrations of Si, SO₄, and TDS.