Nueces Bay Zinc in Oyster Tissue TMDL Project

Nueces Bay Zinc in Oyster Tissue TMDL Project Imane Mrini, David Maidment, Lynn Katz and Jon Goodall Center for Research in Water Resources The University of Texas at Austin

Nueces Bay Zinc TMDL • • Review of past studies What was reported in Jan 2003 What we are reporting now Issues and challenges

Nueces Bay Zinc TMDL • • Previous studies What was reported in Jan 2003 What we are reporting now Issues and challenges

TWDB Hydrodynamic Modeling done for CCBNEP (48 hr average flows)

Predevelopment vs Existing Conditions Shutting down power plants “Predevelopment” Condition Nueces – CCBay circulation “Existing” Condition driven by Power Plants and Ship Channel

Total Loads and Water Quality in the Corpus Christi Bay System (1998 study for CCBNEP) Presented by: Ann Quenzer and Dr. David Maidment Special Thanks: Corpus Christi Bay National Estuary Program Ferdinand Hellweger Dr. Nabil Eid Dr. George Ward Dr. Neal Armstrong

Purpose • To determine the rainfall/runoff relationship • To estimate the point and non-point source loads to the bay system • To quantify the relationship between the total loads and the bay system water quality

Water Quality Analysis Salinity Concentration and Mass Fluxes in Corpus Christi Bay. Finite Segment Analysis Flow of water Transport of Constituents Fluxes Loads Advection Dispersion

Observed vs. Expected Oil and Grease (mg/l) Zinc (µg/l)

Observed vs. Expected Chromium (µg/l) Copper (µg/l)

Conclusions u u u Nonpoint sources are main loading source for most constituents Nitrogen, phosphorus, oil & grease loads are consistent with observed concentrations in the bays Metals loads from land account for only a small part of observed concentrations in bays - a reservoir of metals in the bay sediments?

Other studies • Barrera et al (1995) (US Fish and Wildlife Service) reported: • “[A] notable example was the pollution of the Inner Harbor with zinc as a result of the operation of a smelting facility for thirty-five years [ASARCO, 1942 – 1985]. Several billion tons of zinc were processed during that time and Inner Harbor waters and sediments still remain heavily contaminated. ” • Ward et al (1997): The trend is towards slowly decreasing levels of zinc in sediments

Nueces Bay Zinc TMDL • • Previous studies What was reported in Jan 2003 What we are reporting now Issues and challenges

Zinc Monitoring data Zinc in sediments Zn conc. ( ppm) 71 - 140. 1 - 430. 1 - 864. 1 - 2100

Zinc Monitoring data Total Zinc in water Zinc conc. ( g/L) 15 - 21 21. 1 - 40 40. 1 - 53. 4 53. 5 - 73. 31 - 546

Zinc Monitoring data Water Nueces Bay and Inner Harbor waters are well mixed Sediment

Bioconcentration of Zinc Ratio = 2127 Total Zinc in water ( ~ 47 mg/L) 0. 047 ppm Ratio = 23, 400 Zinc in sediment ( ~ 100 mg/kg) 100 ppm Zinc in Oyster tissue (~ 1100 mg/kg) 1100 ppm Ratio = 11

7/29/2002 2/21/02 7/31/2002 Date 2/19/02 8/17/94 7/12/84 3/10/83 9/23/82 5/5/80 Index level (mg/kg) Zinc in Nueces Bay Oyster tissue (mg/kg wet weight) 2500 2000 1500 1000 500 0 Samples

Nueces Bay Zinc TMDL • • Review of past studies What was reported in Jan 2003 What we are reporting now Issues and challenges

Zinc in Sediments Trend (mg/kg) Segment 1969 -1979 1980 -1989 1990 -2002 Corpus Christi Bay 93 90 62 Nueces Bay 111 148 77 Inner Harbor 667 627 304

TDH Oyster sampling Mean = 1395 ppm Range: 704 -2483 ppm FM 0893 FM 1074 2002 -- 3 samples -- 772. 3 ppm Nueces Causeway site #* Nueces River Tidal /( Nueces Bay #* #* Portland Corpus Christi Bay 181 #$"! 37 #* /( NUECES 181 CP&L discharge site Corpus Christi Inner Harbor Æ0 407 #$"! 37 Æ0 407 Æ0 -- 1282. 5 ppm 0 Æ 2002 -- 4 samples 358 Corpus Christi 286 /( 181

Loadings from point source dischargers The number of self reporting requirements for metals were extremely small. TPCs (Typical pollutant concentrations) were used to obtain a reasonable estimate of constituents loadings to segments of Corpus Christi area. For Nueces bay, about 12% of the industrial discharge of zinc is based on measured loads, and 100% of the municipal discharge is based on estimated loads. Total flow = 0. 05 m 3/s and Total load = 0. 71 kg/d

Nueces River Flow • Nueces River at Mathis (1971 -2000) has average flow 17. 4 m 3/s • Nueces River at Callalen (1991 -2000) has average flow 2. 47 m 3/s • Hence ~ 85% of water discharged from Lake Corpus Christi is withdrawn before reaching Nueces Bay

CP&L Discharge to Nueces Bay • Central Power and Light (self reporting data, June 1998 – May 2000) – average flow 17. 35 m 3/s • Armstrong and Ward (1995) 15. 64 m 3/s • Value used = 16. 5 m 3/s • Other dischargers ~ 0. 05 m 3/s • Total permitted discharge = 16. 55 m 3/s

Total Inflow to Nueces Bay • Nueces River 2. 47 m 3/s • Drainage from areas adjacent to bay – 1. 83 m 3/s • Municipal loading 0. 05 m 3/s • CP&L Station 16. 5 m 3/s

Permitted dischargers City of Portland FM 1074 FM 0893 (! (! £¤ (! Coastal Chemical Co Nueces Bay £¤ 181 Central Power and Light Sublight Entreprises §¨¦ 37 Æ0 407 FM 2292 £¤ 181 (! §¨¦ 37 Æ0 §¨¦ 37 407 Æ0 358 0 286 Æ Corpus Christi Bay

Land surface loadings method Precipitation Land cover/land use Runoff equation Water Q=0 Urban Q = 0. 24 *P Agriculture Q = 0. 008312*exp (0. 011415*P) Range land, Barren, Forest Land , other Q = 0. 0053*exp (0. 010993*P) Land Cover/Land use Zinc EMC ( µg/l) Residential 80 Commercial 180 Industrial 245 Transportation 60 Agriculture 16 Range 6 Mixed 141 Runoff loadings Concentration Load = 3. 69 kg Q = 1. 83 m 3/s

Lake Corpus Christi Loads Freshwater background concentrations of zinc Area Zinc concentration ( g/liter) Reference Various rivers, worldwide 5– 45 a Holland (1978) USA, nationwide 0. 5– 10 US EPA (1987) Lake corpus christi mid lake at the dam TCEQ monitoring station 12967 Lake Corpus Christi ") USA, ambient surface water stations 20 b Eckel & Jacob (1988) • Total zinc assumed to be 20 µg/l in lake Corpus Christi • Nueces River Mean streamflow(1991 -2000) at USGS/callalen = 2. 47 m 3/s !( USGS/Nueces River Nr Mathis Tx USGS/ Nueces River At Calallen !( ") Nueces Bay TCEQ monitoring station 12960 Nuece river N. of Viola Basin Load = Conc × flow = 4. 27 kg/d 0 3, 750 7, 500 15, 000 22, 500 30, 000 Meters

Atmospheric Deposition of Zinc • White Point Station – Wet deposition 1 kg/km 2/yr – Dry deposition 91 kg/km 2/yr • Texas A&M Corpus Christi Station White Point Station – Wet deposition 3 kg/km 2/yr – Dry deposition 52 kg/km 2/yr • Values for White Point station used because of proximity to Nueces Bay • Multiply by bay area (75 km 2) to get atmospheric load TAMUCC Station

CSTR With CPL loads from Inner Harbor Atmospheric deposition Wat = 18. 67 kg/d NPS watershed loadings Qwsh = 1. 83 m 3/s Wwsh = 3. 69 kg/d Lake Corpus Christi load QNR = 2. 47 m 3/s WNR = 4. 27 kg/d Mean = 37µg/L Nueces Bay Permitted discharges Qpd = 0. 05 m 3/s Wpd = 0. 71 kg/d CP&L plant QCP&L = 16. 5 m 3/s WCP&L = 52. 75 kg/d Inner Harbor Average Conc. (1982 -2001) = 37µg/L Outflow

CSTR Model (well-mixed Bay) Non Point Source loadings Atmospheric loadings Point source loadings Outflow Inflow Loading Mixing Mass balance Volume V Decay (k) Steady state concentration For Zinc, decay is negligible k 0

Results Mean = 46. 8µg/l Model with 44. 3µg/l CPL

Nueces Bay Zinc TMDL • • Review of past studies What was reported in Jan 2003 What we are reporting now Issues and challenges

Clean methods for Zn measurement Clean method shows lower concentrations for dissolved zinc 13µg/L 4µg/L

Dissolved vs Total Zinc Total Zn = Dissolved Zn + Zn on particles • Dissolved Zinc – Basis of water quality standards since 1988 – Has been measured using clean methods by estuary program – Data in Nueces Bay is for dissolved Zn since 1988 • Total Zinc – Basis of water quality standards before 1988 – Required for oyster TMDL because oysters feed on all material in water – Is related to total suspended solids in water and other factors (p. H)

Predevelopment vs Existing Conditions Shutting down power plants “Predevelopment” Condition Nueces – CCBay circulation “Existing” Condition driven by Power Plants and Ship Channel