Comprehensive and Critical Period Monitoring Program to Evaluate the Effects of Variable Flow on Biological Resources in the Comal Springs/River Aquatic Ecosystem Final 2011 Annual Report

Author BIO-WEST Inc
Year 2012
Description Annual report for 2011 on biota study of Comal Springs/River
Publisher BIO-WEST Inc
Location Comal Springs/River
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The purpose of this report is to document the results of all aquatic ecosystem monitoring conducted in 2011 at Comal Springs located in New Braunfels, Texas. The monitoring and report preparation was performed by BIO-WEST, Inc. Pflugerville, Texas.

[Excerpted from Executive Summary]
…Following the major flood event in June 2010, the Comal River (and much of Central Texas) plunged into one of the worst droughts in history. As summer air temperatures increased and precipitation was sparse, flows continued to drop in the Comal River. These back to back events provided a unique opportunity to assess the aquatic community, evaluate stressors and compare observations to previous lower than average years. The 2011 Variable Flow study data indicated continued deleterious effects in the Upper Spring Run Reach on both aquatic vegetation and fountain darter populations as full recovery from the 2010 major flood event had not been accomplished in this reach prior to the extended period of drought.

Less severe, but negative effects on aquatic vegetation and fountain darter populations were evident in Landa Lake during the majority of 2011. Aquatic vegetation and fountain darter conditions within the Old Channel remained consistent with post-culvert reconstruction conditions, while New Channel conditions improved during 2011.

Neither water quality parameters measured (including water temperature) throughout the Comal Springs/River ecosystem, nor endangered macroinvertebrate habitat or population data posed concern during the extended drought witnessed in 2011. As such, the juxtaposition of high and low-flow events in 2010 and 2011 caused impacts (some severe) in the certain reaches of the ecosystem, but overall the aquatic communities presently remain intact. As the drought continues, or is broken it will be invaluable to continue to monitor the response and/or recovery of the Comal Springs/River ecosystem.