Bluegills (Lepomis macrochirus) were exposed to the propylene glycol butyl ether ester of 2,4-D in six ponds at Tishomingo, Oklahoma, one concentration per pond in five ponds, and a control pond. The fish and the pond environment were studied for five months to measure chronic effects on the fish and persistence of the herbicide in pond water, bottom sediments, and aquatic vegetation. Small quantities of 2,4-D were found in pond waters for six weeks after application. Residues of 2,4-D were found in vegetation and in bottom sediments in the highest-treated pond for six weeks. No 2,4-D was detected in fish after four days.