Seasonal light characteristics for a newly formed reservoir in Southwestern USA

Seasonal transparency and extinction coefficients are presented for two major habitats in the Lake Powell system, a large newly formed reservoir in the arid southwestern USA. These habitats include a shallow side canyon station subjected to periodic influx of dissolved and suspended materials and an open bay system. Maximum Secchi disk levels in the open bay station were at 7.7 meters with the Secchi disk estimated to disappear at a level of penetration approximating 10% of the solar radiation entering the lake surface. Mean compensation depth was calculated at 11.7 meters. Seasonal extinction coefficient for unfiltered light in the deeper bay station was 0.321 while extinction coefficients for blue, green and red filtered light were 0.323, 0.309 and 0.474 respectively. The effect of periodic influx of dissolved and suspended substances on the underwater light climate and phytoplankton populations are discussed for desert lakes.This study was supported in part by funds provided by the Navajo and Kaiparowits participants.This study was supported in part by funds provided by the Navajo and Kaiparowits participants.