Surface water quality was monitored at 19 stations (2-4 week intervals) in
six drainage basins of Bit: Thicket National preserve of east Texas between
1996 and 1999. The parameters monitored were temperature, dissolved oxygen
, pH, conductivity, current speed, light attenuation, chlorophyll a and con
centrations of ammonium, ortho-phosphate, nitrate and nitrite. The best wat
er quality (low nutrients and chlorophyll a; no hypoxia) was found in the B
ig Sandy Creek, Turkey Creek and Village Creek systems. Water quality in th
e Neches River was also generally good except for instances of moderate alg
al blooms. The: pint Island Bayou system, however, typically showed poor wa
ter quality. Very low current velocities and high concentrations of nutrien
ts: promoted massive spring plankton blooms (chlorophyll a in excess of 100
mug L-1) and subsequent hypoxia/anoxia (dissolved oxygen less than 5 mg L-
1). In this system, hypoxia occurred as early as April and as late as Decem
ber.