The City of Arlington maintains a comprehensive monitoring program to protect water quality of receiving waters within the MS4 and comply with permit requirements . The City of Arlington has elected to perform the required storm event discharge monitoring under Section IV , Section A . 1 : NCTCOG Regional Wet Weather Characterization Program ( RWWCP ) as supplemented by dry weather monitoring and local monthly grab sampling .
Screening and monitoring efforts include dry weather screening , Inner-City Creek Sampling ( Monthly / CRP ), wet weather monitoring ( RWWCP ), and industrial and high-risk runoff monitoring .
I . Dry Weather Monitoring The City ’ s dry weather screening program focuses on detecting the presence of illicit discharges , eliminating illicit connections , and assessing dry weather water quality changes . In the fourth reporting period ( 4RP ), the historical dry weather database ( developed in 2003 ) was integrated with current GPS MS4 mapping activities to provide a clearer picture of the location of the City ’ s outfalls and other stormwater infrastructure . As a result , dry weather sampling was suspended to avoid incorrect and / or improper screening . Re-implementation of the program was initiated in late FY2016 on June 16 , 2016 , after the rainy season .
Screenings continued in FY 2021 to meet TCEQ requirements to screen all areas of the MS4 during the permit term , but not necessarily every outfall . Environmental Specialists within the Environmental Management Group are responsible for conducting all dry weather screening activities . Dry weather screening occurs when there has been no significant precipitation ( less than 0.10 inches ) within 48 hours to ensure flow is not from rainfall runoff . Tests and observations are made when the flow is first observed and again within 24 hours , but no sooner than four hours to increase the potential to detect illicit flows . Five ( 5 ) illicit discharges were found as a result of dry weather screening .
The dry weather outfall screening summary for this reporting period is outlined below . |
Watershed |
Number of outfalls screened / verified |
Number of Outfalls with Flow |
Illicit Connections or Discharges |
Unable to Access |
Rush |
189 |
0 |
0 |
17 |
Lower Village |
57 |
0 |
0 |
6 |
Upper Village |
23 |
1 |
1 |
2 |
Fish |
52 |
0 |
0 |
2 |
Trinity Tributaries |
92 |
0 |
0 |
10 |
Cottonwood |
40 |
0 |
0 |
0 |
Lake Arlington |
37 |
0 |
0 |
10 |
Johnson |
106 |
0 |
0 |
9 |
Walnut |
1 |
0 |
0 |
0 |
Lynn |
10 |
0 |
0 |
0 |
Bowman Branch |
16 |
0 |
0 |
1 |
Grand Total |
623 |
1 |
1 |
57 |
II . Monthly Inner-City Creek Sampling – In Situ Since 1988 , the City of Arlington Environmental Management staff has , monthly , conducted sampling activities in its inner-city creek system . The purpose of monthly inner-city creek sampling is to determine and / or detect the present of illicit discharges . Over time , sites have been added , discontinued , or moved to provide a representative sampling of inner-city creeks . Currently , the city monitors thirty-two ( 32 ) sample sites . Sampling at each of the thirty-two sites includes eleven ( 11 ) water quality parameters determined to provide a good indication of the presence of illicit discharges . Parameters include : pH , dissolved oxygen , specific conductivity , air temperature ,
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