The purpose of this report is to document the results of all aquatic ecosystem monitoring conducted in 2011 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]
…Flows in the San Marcos River in 2011 were similar to previous low flow years (2006, 2009), and similar effects were observed. A decrease in Texas wild-rice coverage and fountain darter population estimates reflected the impact of increased recreation pressure under low flow conditions. However, San Marcos salamander densities remained high despite the lower than average flow conditions. Since salamander habitat is limited to areas near spring upwellings at the head of the system (much of which is under Spring Lake and thus protected from recreation), habitat quality for these animals is influenced less by low-flow conditions and increased recreation pressure. Ongoing changes in spring discharge, recreation pressure, exotic species, and other factors make continued monitoring of this system critical to inform management decisions.