Because the quality of the upper lakes was generally high, so was the quality of Lake Marble Falls. As with the previous year, no fish kills were reported in Lake Marble Falls over the past 12 months. The quality of Lake Travis was good to excellent during the past 12 months. The last time water quality dropped was in August 1997 when the lake had high nutrient and bacteria levels following the June 1997 flood. The flood washed nutrients and large volumes of organic matter, such as leaves, twig, bark and tree limbs, into the lake.
Organic matter uses up oxygen in the decay process.
The nutrients that washed into the lake fed the plankton, the tiny plants and animals in the lake. When the plankton died, they sank also used up oxygen in the decay process. The lower part of Lake Travis, near Arkansas Bend and Mansfield Dam, saw some lingering effects of June 1997 flood. Typically, larger reservoirs such as Travis experience the effects of the flood later and for a longer time than the river or the smaller reservoirs. In August 1997, LCRA and Texas Parks and Wildlife Department personnel investigated the deaths of about 3,000 fish.