Technical Reports Document Library

The purpose of this report is to document the results of all aquatic ecosystem monitoring conducted in 2009 at San Marcos Springs located in San Marcos, Texas. The monitoring and report preparation was performed by BIO-WEST, Inc. Pflugerville, Texas.

[Excerpted from the Executive Summary]
This annual summary report presents a synopsis of methodology used and an account of sampling activities conducted during three sampling events (two Comprehensive Monitoring efforts and one Critical Period low-flow effort) on the Comal Springs/River ecosystem in 2009…. The year 2009 was the culmination of a prolonged drought in central Texas that began in 2007. Discharge in the Comal River was at its lowest since 2000….

The variable flows of 2009 had a myriad of effects on the aquatic vegetation in all reaches. … Fountain darter abundance in the Comal River was again variable in 2009, but within the range of previous years observed throughout this study. … In areas near spring upwellings with native vegetation (e.g., bryophytes) there appears to be year-round reproduction. However, dip net data confirm an early spring reproductive peak for these fish in other areas of lower quality habitat. …

Although the total number of Comal Springs riffle beetles (Heterelmis comalensis) captured decreased slightly from 2008 to 2009, numbers were similar to those observed in 2007. … The total number of salamanders observed during the spring and Critical Period sampling efforts were the highest since the inception of the study….

Flows from Comal Springs in 2009 were the lowest observed since 2000, but impacts on the biota in the ecosystem appeared to be minimal. Continued monitoring over an extended period of lower than average flows is necessary to fully understand the impact of discharge on the varied biota in the system.