Water Quality/Variable Flow Study Summary of Fall Quarterly Sampling Comal River, New Braunfels, Texas November 9-17, 2000
This Annual Summary Report serves only to highlight the sampling activities that were conducted with respect to the Fall Quarterly Sampling (Comprehensive Monitoring Effort) on the Comal Springs I River ecosystem. The report presents the sampling activities, brief summary of methodologies, sample locations, and raw data. The report also serves to satisfy the requirements of the Federal Fish and Wildlife Permit # TE820022-2. The data reduction and analysis component of the project will be presented in the final report to be issued to the Edwards Aquifer Authority in February 2003.
The PBS&J project team conducted the Fall Quarterly Sampling from 9 November to 17 November 2000 with the flows at Comal reporting 314 cfs on 9 November 2000, and 344 cfs on 17 November 2000. …
From the time of the Critical Period Monitoring efforts, a considerable amount of rainfall had accumulated and the aquifer experienced a considerable rise. The flows reported during this fall quarterly event were approximately twice those reported during the critical period events. Again, all three major springs (Spring runs 1, 2, and 3) were flowing. Water quality was also measured for the system during this period with the standard parameters (including temperature) being suitable for the biological communities. Aquatic vegetation was abundant and provided suitable habitat for biological communities.
Within the four reaches sampled for fountain darters via the drop net methodology, suitable habitat for the darter was observed. Drop net sampling in all reaches produced fountain darters within the suitable aquatic vegetation types, sometimes in large numbers as documented in Landa Lake. Although a few darters were collected in the drop nets from the Upper Spring Run Reach during the Fall Quarterly sampling, follow-up dip net sampling for fountain darters in this reach was less productive than during the critical period events. In addition, dip net sampling was conducted in Landa Lake and the Old Channel.
Using dip nets, fountain darters were collected from all reaches with large numbers being reported in the suitable habitat in Landa Lake and the Old Channel. Within the spring runs and at the springs’ orifices, suitable habitat for the listed invertebrates was observed. Drift net samples were taken in Spring runs 1, 2, and 3. Suitable habitat for the Comal Springs salamander was also noted in the spring runs and Spring Island area with salamanders observed in each area.
Unlike the first two events, the filamentous algae and floating mats of vegetation that had been present was thoroughly removed prior to the fall quarterly sampling. The gill parasite that has been reported for the fountain darter over the last several years was also very evident in a number of fountain darters collected. The fountain darters collected from the Old Channel Reach exhibited the worst conditions noted with respect to parasite infections and darter condition.
The fall quarterly effort conducted at approximately twice the Critical Period flow provided an excellent confirmation that the study design appears well suited to address the concerns of variable flow and water quality on the biological resources in the Comal system. It must continue to be emphasized that additional sampling in variable flow conditions to compare back to this fall quarterly sampling effort and future efforts remains critically important in order to best define and understand the system.