Lavaca Bay TMDL Dissolved Oxygen Assessment Report

Date

2003-12-15

Authors

Montagna, Paul A.
Russell, Marc James, 1975-

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Description

"This project provides technical support to the Texas Commission on Environmental Quality (TCEQ) for the development of a Total Maximum Daily Load (TMDL). The TCEQ will lead an effort to assess the causes and sources of the following water quality problems identified in the Texas 2000 Clean Water Act 303(d) list for Lavaca Bay/Chocolate Bay (Segment 2453). The segment is located in Calhoun county in southeast Texas near the Cities of Point Comfort and Port Lavaca. The TCEQ water quality segment 2453 (Lavaca Bay/Chocolate Bay) currently has aquatic life closure for 2.5 square miles of the segment because of elevated mercury (Hg) levels in fin fish and crabs. In the Alcoa Ship Channel, the average Hg concentration in water exceeds the human health criterion for saltwater fish. In a 13.7-square mile area near Alcoa Ship Channel, dissolved oxygen (DO) concentrations are occasionally lower than the criteria established to assure to optimum conditions to support exceptional aquatic life use. This document reports on the monitoring and assessment activities for DO conditions. Based on the historical data review, the area within Segment 2435 with low DO is primarily in deeper navigation channels and it occurs primarily in summer. The goal of the current project was to collect sufficient data to perform an assessment of DO conditions in Lavaca Bay to determine if this segment should remain on the 303d list and if a TMDL process is required for these two characteristics of water quality. A separate report (entitled 'Lavaca Bay Mercury TMDL Project,' November 2003, and attached as Appendix C) was prepared for the mercury sampling and assessment"--Executive summary.
Project Title: Lavaca Bay Mercury and Dissolved Oxygen Total Maximum Daily Load (TMDL) Assessment
Final Report Submitted To: Texas Commission On Environmental Quality

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