Water Quality/Variable Flow Study Summary of Critical Period Sampling #1 Comal River, New Braunfels, Texas August 23-31, 2000
This Annual Summary Report serves only to highlight the sampling activities that were conducted with respect to the First Critical Period 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. …
At the flows present (177 – 161 cfs) during the first Critical Period Monitoring effort, 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 the lower three reaches produced fountain darters within the suitable aquatic vegetation types, sometimes in large numbers as documented in Landa Lake and the Old Channel. No fountain darters were collected in drop nets from the Upper Spring Run Reach. However, subsequent dip net sampling in the Upper Spring Run Reach for fountain darters revealed that darters still occupied the reach. In addition, dip net sampling was conducted in Landa Lake, the New Channel, the Old Channel, and below Garden Street just above the confluence with the Guadalupe River. 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 in1vertebrates was observed. Drift net samples were taken in Spring runs I, 2, and 3. Suitable habitat for the Coma) Springs salamander was also noted in the spring runs and Spring Island area with salamanders observed in each area.
There was a considerable amount of filamentous green algae in the Upper Spring Run Reach, covering the majority of the substrate and the aquatic vegetation to varying degrees. This condition was much less evident in the lower reaches. 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. It should be emphasized that the parasite has been repeatedly noted for darters in the Comal System and that the Old Channel maintained some of the highest flows sampled during this effort.
The study design appears well suited to address the concerns of variable flow and water quality on the biological resources in the Comal system. Sampling in variable flow conditions to compare back to this critical period sampling effort and future efforts remains critically important in order to best define and understand the system.