The Impairment and Concerns summarized the assessment results by assessment units in the San Antonio River Watershed as indentified in the Texas Commission on Environment Quality (TCEQ) 2014 Integrated Report (IR)

The Integrated Report is a biennial report describing the status of the state’s surface waters, as required by Sections 305(b) and 303(d) of the federal Clean Water Act. Main water segments in the San Antonio Watershed are divided into assessment units (AU) which are assigned an integrated level of support category based on water quality data availability and analysis for the IR period of record start and end dates – typically seven years.

The IR is structured in the following manner:

Segment ID A water body or portion of a water body that is individually defined in the Texas Surface Water Quality Standards. The classified segments are assigned four-digit numbers (e.g. 1901), while an unclassified segment is five-digit (e.g. 1901A). The first two digits correspond to the major basin in which they are located. The last two digits distinguish individual segments within the particular basin. The San Antonio River Watershed consists of the following classified segments.

• 1901 - Lower San Antonio River
• 1902 - Lower Cibolo Creek
• 1903 - Medina River Below Medina Diversion Lake
• 1904 - Medina Lake
• 1905 - Medina River Above Medina Lake
• 1906 - Lower Leon Creek
• 1907 - Upper Leon Creek
• 1908 - Upper Cibolo Creek
• 1909 - Medina Diversion Lake
• 1910 - Salado Creek
• 1911 - Upper San Antonio River
• 1912 - Medio Creek
• 1913 - Mid Cibolo Creek

AUID Identifies the assessment unit (AUID, six or seven digits, e.g., 1901A_01) and describes the location of the specific area within a classified or unclassified water body for which one or more water quality standards are not met.

Use The purposes for which the water should be suitable. Each water body is assigned uses and criteria or parameters consistent with the Texas Water Quality Standards that are evaluated against ambient water quality data for determining support or attainment of the use.
TCEQ - What is Quality?

Method A group of parameters, e.g. Nutrient Screening Levels consists of the following parameters: Nitrate, Ammonia, Total Phosphorus, and Chlorophyll-a.

Parameter is a pollutant or water quality condition that assessment procedures indicate meet or do not meet the assigned water quality standards or screening levels (e.g. Ammonia, E.coli, and Dissolved Oxygen Grab).

Integrated Level of Support is the overall level of support for this use, method, parameter group, which could be different from the Level of Support (LOS).

Integrated Level of Support Category
FS - Fully Supporting (Not Impaired)
NC - No Concern (Not Impaired)
NA - Not Assessed (Not Impaired)
NS - Nonsupport (Impaired)
CS - Screening Level Concern (Concern)
CN - Use Concern (Concern)

Source Credits