The Bonnet Carré Spillway, located about 28 miles northwest of New Orleans, Louisiana, was constructed in the early 1930s as part of an integrated flood-control structure for the lower Mississippi River Plain. The spillway is designed to divert water from the Mississippi River into Lake Pontchartrain, thus relieving pressure on levees downstream. Opening of the spillway occurs when measured streamflow in the Mississippi River at New Orleans exceeds 1.25 million cubic feet per second, which normally occurs late in the spring season. Over the approximately 90 years since its construction, the spillway has been opened only twelve times; however, in 2019, it was opened twice. Monitoring the quality of surface waters receiving diverted Mississippi River water including Lake(s) Pontchartrain and Borgne and the Mississippi Sound is of vital importance to public- and natural resource managers in Louisiana and Mississippi. These bodies of water provide crucial habitat for fish, crabs and other shellfish, seagrasses, and marine mammals, such as dolphins and manatees. Coastal waters are also used for recreation and commercial fishing.
The U.S. Geological Survey (USGS), Lower Mississippi-Gulf Water Science Center (LMG), in cooperation with the U.S. Army Corp of Engineers (USACE) New Orleans District, has sampled water from Lake Pontchartrain, Lake Borgne, and the western Mississippi Sound prior, during, and after each spillway opening from 2008 to present. In 2020, discrete water-quality samples are being collected at all stations in Lake(s) Pontchartrain and Borgne and the western Mississippi Sound (map thumbnail) except at Rigolets at Hwy 90 near Slidell, LA (RIG) and East Pearl River at CSX Railroad near Claiborne, MS (EPR). Samples are analyzed for major ions, nutrients, inorganic plus organic particulate carbon, total suspended solids, chlorophyll a, phytoplankton composition, and algal toxins. Euphotic depths are determined from Secchi depth readings and then used to guide the sample collection depths for chlorophyll, phytoplankton, and algal toxins. Currently, the USGS-LMG also measures continuous water quality (stage, salinity, and temperature) at five stations in the western Mississippi Sound (Table 1).
A multi-parameter data sonde is used at each of the sites at the time of sample collection to measure water temperature, specific conductance, salinity, dissolved oxygen, and pH typically at 0.5 meters above the bottom depth, mid-depth, and 0.5 meters below the water surface to document any salinity or dissolved-oxygen stratifications within the water column. These field data are useful in monitoring changes in salinity and stratification that influence biological processes in the lake and sound waters.
USACE Spillway Operation Information
| USGS Station ID | USGS Station Name | Latitude | Longitude | Station Abbreviation | Station Type | Field Parameters | Laboratory Water Quality |
|---|---|---|---|---|---|---|---|
| 300115090245000 | Bonnet Carré Spillway at US Hwy 61 near Norco, LA | 30.02083 | -90.413889 | BC | Discrete | X | X |
| 301853090060700 | Lake Pontchartrain at Causeway Bridge near Mandeville | 30.31472 | -90.101944 | C1 | Discrete | X | X |
| 301528090064600 | Lake Pontchartrain at Causeway Bridge near Mandeville, LA | 30.25778 | -90.112778 | C2 | Discrete | X | X |
| 301200090072400 | Lake Pontchartrain at Crossover 4 near Mandeville, LA | 30.19964 | -90.12275 | C4 | Discrete | X | |
| 300412090084300 | Lake Pontchartrain at Causeway Bridge near Metairie | 30.07 | -90.145278 | C7 | Discrete | X | X |
| 301050089511600 | Lake Pontchartrain at Hwy 11 Causeway near Slidell | 30.18056 | -89.854444 | H11 | Discrete | X | X |
| 300218089374500 | Lake Borgne 5.5 miles east of Alligator Point, LA | 30.03833 | -89.629167 | LB | Discrete | X | X |
| 300454089284200 | Western Mississippi Sound near Le Petit Pass Island, LA | 30.08166 | -89.47839 | PP | Discrete | X | |
| 300233089224200 | Western Mississippi Sound near Three Mile Bay, LA | 30.04236 | -89.37823 | TM | Discrete | X | |
| 301001089442600 | Rigolets at Hwy 90 near Slidell, LA | 30.16694 | -89.74056 | RIG | Continuous | ||
| 301141089320300 | E. Pearl River at CSX RR near Claiborne, MS | 30.19472 | -89.53417 | EPR | Continuous | ||
| 301104089253400 | Mississippi Sound at St. Joseph Island Light, MS | 30.19083 | -89.42222 | SJ | Continuous | X | X |
| 301429089145600 | Mississippi Sound at Merrill Shell Bank Light, MS | 30.23806 | -89.242778 | MB | Continuous | X | X |
| 300722089150100 | Mississippi Sound near Grand Pass, LA | 30.12278 | -89.2502778 | GP | Continuous | X | X |
| 301746089143500 | MB2, 1 mile south of Pass Christian, MS | 30.29608 | -89.24317 | MB2 | Discrete | X | |
| 301636089144400 | MB1, 2.5 miles north of Merrill Bank, MS | 30.27665 | -89.24555 | MB1 | Discrete | X | |
| 301252089150400 | GP2, 6 miles north of Grand Pass, LA | 30.21452 | -89.25105 | GP2 | Discrete | X | |
| 301047089150200 | GP1, 3 miles north of Grand Pass, LA | 30.1796 | -89.25063 | GP1 | Discrete | X |
Table 2.1 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of April 6–10, 2020, spillway week 1*
| Station Abbreviation | Date | Time (CST) | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| BC | 4/9/2020 | 1131 | 0.9 | 16.6 | 315 | 0.1 | 9.2 | 7.7 | 0.4 |
| 1132 | 3.9 | 16.6 | 315 | 0.1 | 9.2 | 7.7 | - | ||
| 1133 | 8.8 | 16.6 | 315 | 0.1 | 9.2 | 7.7 | - | ||
| C1 | 4/8/2020 | 1001 | 0.9 | 23.9 | 676 | 0.3 | 8.7 | 7.8 | 0.55 |
| 1002 | 7.4 | 23.6 | 688 | 0.3 | 8.3 | 7.6 | - | ||
| 1003 | 15.1 | 23.6 | 728 | 0.3 | 8.2 | 7.6 | - | ||
| C2 | 4/8/2020 | 1101 | 0.7 | 23.9 | 774 | 0.3 | 8.7 | 7.7 | 0.5 |
| 1102 | 8.1 | 23.4 | 791 | 0.3 | 7.4 | 7.4 | - | ||
| 1103 | 15.9 | 23.5 | 802 | 0.3 | 7.3 | 7.3 | - | ||
| C4 | 4/8/2020 | 1130 | 0.2 | 24.2 | 898 | 0.4 | 8.9 | 7.9 | 0.7 |
| 1131 | 8.6 | 24.2 | 976 | 0.4 | 8.2 | 7.4 | - | ||
| 1132 | 16.7 | 23.3 | 880 | 0.4 | 8.1 | 7.3 | - | ||
| C7 | 4/8/2020 | 1201 | 0.8 | 23.5 | 1,170 | 0.6 | 8.4 | 7.7 | 1.05 |
| 1202 | 7.6 | 23.4 | 1,170 | 0.6 | 8.4 | 7.6 | - | ||
| 1203 | 14.5 | 23.4 | 1,180 | 0.6 | 8.2 | 7.5 | - | ||
| H11 | 4/9/2020 | 1131 | 0.9 | 24.8 | 1,130 | 0.6 | 8.1 | 7.8 | 0.4 |
| 1132 | 6.4 | 24.8 | 1,130 | 0.6 | 8.1 | 7.8 | - | ||
| 1133 | 13.1 | 24.8 | 1,130 | 0.6 | 8.1 | 7.6 | - |
Table 2.2 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of April 20–24, 2020, spillway week 3*
| Station Abbreviation | Date | Time (CST) | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| BC | 4/16/2020 | 1000 | 1.5 | 16.9 | 320 | 0.0 | 8.6 | 7.7 | 0.7 |
| SJ | 4/20/2020 | 1201 | 0.3 | 22.9 | 2,380 | 1.2 | 8.2 | 7.4 | 0.25 |
| 1202 | 4.8 | 22.7 | 2,440 | 1.2 | 8.1 | 7.3 | - | ||
| 1203 | 9.8 | 22.4 | 2,840 | 1.5 | 8 | 7.3 | - | ||
| MB2 | 4/20/2020 | 0945 | 1.5 | 22 | 12,100 | 6.9 | 8.7 | 7.8 | 0.8 |
| 0946 | 4.4 | 21.8 | 15,700 | 9.2 | 8.2 | 7.7 | - | ||
| 0947 | 9.3 | 20.9 | 26,000 | 16.0 | 5.1 | 7.3 | - | ||
| MB1 | 4/20/2020 | 0930 | 0.9 | 22.2 | 10,500 | 6.0 | 9.2 | 8 | 0.65 |
| 0932 | 5.7 | 21.9 | 11,900 | 6.8 | 7.8 | 7.7 | - | ||
| 0932 | 11.6 | 21.1 | 23,400 | 14.0 | 5.7 | 7.4 | - | ||
| MB | 4/20/2020 | 1131 | 1.1 | 21.9 | 8,290 | 4.6 | 8.3 | 7.7 | 0.7 |
| 1132 | 7.3 | 21.8 | 8,270 | 4.6 | 8.1 | 7.7 | - | ||
| 1133 | 14.8 | 21 | 24,300 | 15.0 | 6.5 | 7.3 | - | ||
| GP2 | 4/20/2020 | 1015 | 0.7 | 22 | 7,970 | 4.0 | 8.9 | 8 | 0.7 |
| 1016 | 5.7 | 21.9 | 7,990 | 4.0 | 8.4 | 7.9 | - | ||
| 1017 | 11.5 | 20.9 | 24,900 | 15.0 | 5.9 | 7.4 | - | ||
| GP1 | 4/20/2020 | 1000 | 1.3 | 21.9 | 7,080 | 4.0 | 8.6 | 7.9 | 0.7 |
| 1001 | 6.7 | 21.7 | 7,160 | 4.0 | 8.2 | 8 | - | ||
| 1002 | 13.1 | 21 | 34,800 | 22.0 | 6.4 | 7.7 | - | ||
| GP | 4/20/2020 | 1031 | 1.2 | 22.3 | 10,900 | 8.8 | 8.8 | 7.8 | 0.6 |
| 1032 | 3.6 | 22.2 | 10,900 | 8.6 | 8.6 | 7.9 | - | ||
| 1033 | 9.3 | 21.9 | 11,300 | 8.2 | 8.2 | 7.8 | - | ||
| LB | 4/21/2020 | 1031 | 0.7 | 23.1 | 1,370 | 0.7 | 9.5 | 8.3 | 0.25 |
| 1032 | 6.5 | 22.2 | 1,360 | 0.7 | 8.5 | 7.8 | - | ||
| 1033 | 11.2 | 22.2 | 1,370 | 0.7 | 8.4 | 7.9 | - | ||
| PP | 4/20/2020 | 1400 | 0.5 | 23 | 2,070 | 1.0 | 8.9 | 7.8 | 0.2 |
| 1401 | 5.6 | 22.3 | 2,070 | 1.0 | 8.6 | 7.7 | - | ||
| 1402 | 11.3 | 22.1 | 2,070 | 1.0 | 8.6 | 7.7 | - | ||
| TM | 4/20/2020 | 1250 | 0.3 | 23.4 | 2,850 | 1.9 | 9.1 | 8 | 0.2 |
| 1251 | 2.8 | 23.1 | 2,880 | 2.0 | 8.9 | 7.9 | - | ||
| 1252 | 5.9 | 22.5 | 3,230 | 2.0 | 8.6 | 7.8 | - |
Table 2.3 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of April 27 – May 1, 2020, spillway week 4*
| Station Abbreviation | Date | Time (CST) | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 4/28/2020 | 1001 | 1 | 22.6 | 857 | 0.4 | 12.2 | 7.5 | 0.6 |
| 1002 | 8.1 | 22.7 | 859 | 0.4 | 8.3 | 7.4 | - | ||
| 1003 | 15.6 | 22.7 | 859 | 0.4 | 8.2 | 7.3 | - | ||
| C2 | 4/28/2020 | 1101 | 0.99 | 22.3 | 860 | 0.4 | 8.5 | 7.5 | 0.55 |
| 1102 | 9.1 | 22.4 | 853 | 0.4 | 8.4 | 7.4 | - | ||
| 1103 | 15.9 | 22.4 | 853 | 0.4 | 8 | 7.3 | - | ||
| C4 | 4/28/2020 | N/A | - | - | - | - | - | - | - |
| C7 | 4/28/2020 | 1201 | 1.9 | 21.7 | 343 | 0.2 | 9 | 7.9 | 0.75 |
| 1202 | 8.8 | 21.6 | 343 | 0.2 | 8.9 | 7.9 | - | ||
| 1203 | 16.1 | 21.6 | 343 | 0.2 | 8.8 | 7.8 | - | ||
| H11 | 4/29/2020 | 1131 | 1.5 | 22.4 | 437 | 0.2 | 8.5 | 8 | 0.25 |
| 1132 | 6.5 | 22.4 | 437 | 0.2 | 8.5 | 7.9 | - | ||
| 1133 | 12.9 | 21.4 | 437 | 0.2 | 8.5 | 7.9 | - |
Table 2.4 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of May 25–29, 2020, week 4 after spillway was closed
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 5/26/2020 | 1001 | 2.1 | 27 | 944 | 0.5 | 7.4 | 7.5 | 0.7 |
| 1002 | 9.7 | 26.9 | 943 | 0.5 | 7.4 | 7.5 | - | ||
| 1003 | 16 | 26.9 | 943 | 0.5 | 7.4 | 7.5 | - | ||
| C2 | 5/26/2020 | 1101 | 0.7 | 26.8 | 686 | 0.3 | 7.7 | 7.5 | 0.7 |
| 1102 | 8.1 | 26.7 | 683 | 0.3 | 7.5 | 7.4 | - | ||
| 1103 | 16.5 | 26.6 | 711 | 0.3 | 7.4 | 7.3 | - | ||
| C4 | 5/26/2020 | 1131 | 1.2 | 26.9 | 814 | 0.4 | 7.8 | 7.6 | 0.55 |
| 1132 | 8.7 | 26.7 | 814 | 0.4 | 7.6 | 7.4 | - | ||
| 1133 | 17.8 | 26.6 | 814 | 0.4 | 7.5 | 7.3 | - | ||
| C7 | 5/26/2020 | 1201 | 1.3 | 27.1 | 547 | 0.3 | 7.6 | 7.5 | 0.7 |
| 1202 | 8.8 | 26.7 | 548 | 0.3 | 7.4 | 7.5 | - | ||
| 1203 | 16.6 | 26.7 | 548 | 0.3 | 7.4 | 7.4 | - | ||
| H11 | 5/27/2020 | 1131 | 1.9 | 27.6 | 438 | 0.2 | 7.9 | 7.8 | 0.2 |
| 1132 | 8.6 | 27.1 | 619 | 0.3 | 7.8 | 7.8 | - | ||
| 1133 | 15.6 | 26.9 | 869 | 0.4 | 7.6 | 7.7 | - |
Table 2.5 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of June 1–5, 2020, week 5 after spillway was closed
| Station Abbreviation | Date | Time (CST) | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| SJ | 6/2/2020 | 1401 | 1 | 27.6 | 10,100 | 5.7 | 7.2 | 7.7 | 0.5 |
| 1402 | 6.5 | 27.6 | 10,100 | 5.7 | 7.2 | 7.7 | - | ||
| 1403 | 11 | 27.6 | 10,100 | 5.7 | 7.2 | 7.7 | - | ||
| MB2 | 6/2/2020 | 1100 | 1.2 | 27.7 | 17,800 | 10.5 | 7.5 | 8.1 | 1.1 |
| 1101 | 6.3 | 27.7 | 18,100 | 10.7 | 7 | 8 | - | ||
| 1102 | 10.1 | 27.8 | 18,800 | 11.1 | 6.3 | 7.8 | - | ||
| MB1 | 6/2/2020 | 1115 | 0.8 | 27.7 | 18,100 | 10.7 | 7.9 | 8.2 | 1.3 |
| 1116 | 4.6 | 27.7 | 18,200 | 10.7 | 7.6 | 8.1 | - | ||
| 1117 | 9.1 | 27.7 | 19,100 | 11.3 | 7.1 | 8.1 | - | ||
| MB | 6/2/2020 | 1131 | 1.3 | 27.7 | 17,800 | 10.5 | 7.4 | 8.1 | 1.3 |
| 1132 | 4.3 | 27.6 | 17,800 | 10.5 | 7.1 | 8 | - | ||
| 1133 | 15.2 | 27.5 | 22,700 | 13.6 | 3.3 | 7.7 | - | ||
| GP2 | 6/2/2020 | 1000 | 0.6 | 27.8 | 20,100 | 11.9 | 7.6 | 8.2 | 1.15 |
| 1001 | 6.1 | 27.8 | 20,300 | 12.1 | 7.3 | 8.2 | - | ||
| 1002 | 12.1 | 27.4 | 23,500 | 14.2 | 4.2 | 7.8 | - | ||
| GP1 | 6/2/2020 | 1015 | 1.6 | 27.7 | 20,900 | 12.5 | 8 | 8.3 | 0.95 |
| 1016 | 6.5 | 27.6 | 23,600 | 14.2 | 7.4 | 8.3 | - | ||
| 1017 | 13.6 | 27.6 | 25,800 | 15.7 | 6.8 | 8.2 | - | ||
| GP | 6/2/2020 | 1031 | 0.7 | 27.6 | 18,900 | 11.2 | 5 | 7.8 | 0.65 |
| 1032 | 5.5 | 27.6 | 19,000 | 11.2 | 6 | 7.9 | - | ||
| 1033 | 11.1 | 27.3 | 20,900 | 12.5 | 2.9 | 7.6 | - | ||
| LB | 6/2/2020 | 1301 | 1.1 | 27.8 | 3,280 | 1.7 | 7.5 | 8 | 0.55 |
| 1302 | 6.8 | 27.8 | 3,260 | 1.7 | 7.5 | 8 | - | ||
| 1303 | 11.9 | 27.8 | 3,260 | 1.7 | 7.5 | 8.1 | - | ||
| PP | 6/2/2020 | 1245 | 0.9 | 27.8 | 6,520 | 3.5 | 7.3 | 8 | 0.4 |
| 1246 | 6.2 | 27.8 | 6,520 | 3.5 | 7.2 | 7.9 | - | ||
| 1247 | 12.6 | 27.8 | 6,550 | 3.5 | 7.2 | 7.9 | - | ||
| TM | 6/2/2020 | 1230 | 1 | 27.9 | 9,030 | 5.0 | 7.1 | 7.8 | 0.55 |
| 1231 | 4.7 | 27.8 | 9,110 | 5.1 | 6.8 | 7.8 | - | ||
| 1232 | 7.1 | 27.7 | 9,410 | 5.3 | 5.4 | 7.9 | - |
Table 2.6 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of June 22–26, 2020, week 8 after spillway was closed
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 6/23/2020 | 1001 | 1.79 | 28.2 | 597 | 0.3 | 7.1 | 7 | 0.75 |
| 1002 | 8.43 | 28.2 | 597 | 0.3 | 7.1 | 6.9 | - | ||
| 1003 | 14.4 | 28.2 | 597 | 0.3 | 7.1 | 6.8 | - | ||
| C2 | 6/23/2020 | 1101 | 2.28 | 28 | 710 | 0.3 | 7.2 | 7.2 | 0.9 |
| 1102 | 8.66 | 28 | 710 | 0.3 | 7.1 | 7.1 | - | ||
| 1103 | 15.2 | 28 | 710 | 0.3 | 7 | 7 | - | ||
| C4 | 6/23/2020 | 1130 | 1.27 | 27.9 | 613 | 0.3 | 7.3 | 7.2 | 1.1 |
| 1131 | 8.64 | 27.9 | 613 | 0.3 | 7.2 | 7.2 | - | ||
| 1132 | 16.5 | 27.9 | 613 | 0.3 | 7.1 | 7.1 | - | ||
| C7 | 6/23/2020 | 1201 | 1.18 | 27.7 | 643 | 0.3 | 7.2 | 7.4 | 1 |
| 1202 | 8.67 | 27.7 | 643 | 0.3 | 7.2 | 7.3 | - | ||
| 1203 | 15.2 | 27.7 | 643 | 0.3 | 7.1 | 7.2 | - | ||
| H11 | 6/23/2020 | 1301 | 1.49 | 27.8 | 1,410 | 0.7 | 6.7 | 7.1 | 0.55 |
| 1302 | 7.88 | 27.7 | 1,400 | 0.7 | 6.5 | 7 | - | ||
| 1303 | 13.6 | 27.7 | 1,400 | 0.7 | 6.5 | 6.9 | - |
Table 2.7 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of July 20–24, 2020, week 12 after spillway was closed
| Station Abbreviation | Date | Time (CST) | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| SJ | 7/21/2020 | 1401 | 0.6 | 29.9 | 32,100 | 19.9 | 6.6 | 7.9 | 0.5 |
| 1402 | 3 | 29.8 | 32,100 | 19.9 | 6.6 | 7.9 | - | ||
| 1403 | 9.8 | 29.8 | 32,100 | 19.9 | 6.4 | 7.9 | - | ||
| MB2 | 7/20/2020 | 1100 | 0.4 | 30.6 | 34,400 | 21.4 | 7.1 | 6.8 | 0.8 |
| 1101 | 4.5 | 30.6 | 34,400 | 21.4 | 7.1 | 6.8 | - | ||
| 1102 | 9.1 | 30.6 | 34,400 | 21.4 | 7 | 6.8 | - | ||
| MB1 | 7/20/2020 | 1115 | 0.5 | 30.4 | 35,900 | 22.5 | 7.2 | 6.3 | 0.9 |
| 1116 | 6 | 30.3 | 36,000 | 22.6 | 7.1 | 6.3 | - | ||
| 1117 | 12.9 | 30.3 | 36,100 | 22.6 | 7 | 6.2 | - | ||
| MB | 7/20/2020 | 1131 | 1 | 30 | 40,400 | 25.7 | 7 | 6.3 | 0.8 |
| 1132 | 9 | 29.9 | 40,400 | 25.7 | 6.9 | 6.3 | - | ||
| 1133 | 15.3 | 29.9 | 40,400 | 25.7 | 6.9 | 6.3 | - | ||
| GP2 | 7/21/2020 | 1015 | 1.3 | 29.6 | 37,300 | 23.5 | 6.5 | 8.1 | 0.9 |
| 1016 | 6.2 | 29.5 | 38,000 | 24.0 | 6 | 8.1 | - | ||
| 1017 | 11.4 | 29.5 | 38,500 | 24.4 | 5.8 | 8.1 | - | ||
| GP1 | 7/21/2020 | 1000 | 0.8 | 29.6 | 39,800 | 25.3 | 5.4 | 8.1 | 0.65 |
| 1001 | 7.1 | 29.6 | 39,800 | 25.3 | 5.4 | 8.1 | - | ||
| 1002 | 14.1 | 29.6 | 39,800 | 25.3 | 5.3 | 8.1 | - | ||
| GP | 7/21/2020 | 1031 | 0.8 | 29.4 | 36,200 | 22.8 | 5.8 | 7.9 | 0.45 |
| 1032 | 5.2 | 29.3 | 36,200 | 22.8 | 5.7 | 7.9 | - | ||
| 1033 | 10.6 | 29.3 | 36,200 | 22.8 | 5.6 | 7.9 | - | ||
| LB | 7/21/2020 | 1301 | 1.1 | 29.7 | 15,600 | 9.0 | 7.3 | 7.9 | 0.5 |
| 1302 | 5.4 | 29.7 | 15,600 | 9.0 | 7.3 | 7.9 | - | ||
| 1303 | 11.1 | 29.7 | 15,600 | 9.0 | 7.2 | 7.9 | - | ||
| PP | 7/21/2020 | 1200 | 1.2 | 29.2 | 22,600 | 13.6 | 6.6 | 7.8 | 0.45 |
| 1201 | 7.2 | 29.2 | 22,700 | 13.6 | 6.5 | 7.8 | - | ||
| 1202 | 13.4 | 29.2 | 22,900 | 13.7 | 5.9 | 7.7 | - | ||
| TM | 7/21/2020 | 1130 | 0.8 | 29.8 | 18,500 | 10.9 | 7.8 | 8 | 0.35 |
| 1131 | 3.2 | 29.7 | 19,000 | 11.2 | 7.4 | 8 | - | ||
| 1132 | 5.4 | 29.2 | 23,700 | 14.3 | 4.4 | 7.6 | - |
Table 2.8 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of July 27–31, 2020, week 13 after spillway was closed
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 7/27/2020 | 1001 | 1.5 | 27.7 | 361 | 0.2 | 7.7 | 8.1 | 1 |
| 1002 | 8.75 | 27.7 | 361 | 0.2 | 7.6 | 8.1 | - | ||
| 1003 | 16 | 27.7 | 361 | 0.2 | 7.6 | 8.2 | - | ||
| C2 | 7/27/2020 | 1101 | 1.4 | 27.7 | 1,770 | 0.9 | 7.3 | 7.7 | 1.1 |
| 1102 | 8.8 | 27.7 | 1,930 | 1.0 | 7.1 | 7.7 | - | ||
| 1103 | 16.4 | 28 | 4,360 | 2.3 | 6 | 7.5 | - | ||
| C4 | 7/27/2020 | 1115 | 1.65 | 27.6 | 3,430 | 1.8 | 7.4 | 7.8 | 1.1 |
| 1116 | 7 | 27.6 | 3,440 | 1.8 | 7.3 | 7.8 | - | ||
| 1117 | 17.6 | 28.1 | 4,610 | 2.5 | 4.9 | 7.3 | - | ||
| C7 | 7/27/2020 | 1201 | 1.57 | 27.7 | 559 | 0.3 | 7.2 | 7.8 | 1.1 |
| 1202 | 8.76 | 27.7 | 559 | 0.3 | 7.2 | 7.8 | - | ||
| 1203 | 16.6 | 27.7 | 558 | 0.3 | 7.4 | 7.9 | - | ||
| H11 | 7/27/2020 | 1301 | 0.7 | 27.1 | 6,520 | 3.6 | 7.2 | 7.7 | 1 |
| 1302 | 8.5 | 27.1 | 6,520 | 3.6 | 7.2 | 7.7 | - | ||
| 1303 | 15.6 | 27.1 | 6,530 | 3.6 | 7.2 | 7.7 | - |
Table 2.9 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of August 31 – September 4, 2020, week 18 after spillway was closed
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 9/1/2020 | 1001 | 1.8 | 29.1 | 2,350 | 1.2 | 7 | 7.3 | 1.2 |
| 1002 | 8 | 29.1 | 2,380 | 1.2 | 6.9 | 7.2 | - | ||
| 1003 | 14.9 | 28.6 | 7,420 | 4.1 | 6.5 | 1.3 | - | ||
| C2 | 9/1/2020 | 1101 | 1.1 | 28.8 | 2,160 | 1.1 | 7.6 | 7.5 | 0.75 |
| 1102 | 7.9 | 28.8 | 2,250 | 1.1 | 7.5 | 7.4 | - | ||
| 1103 | 15.6 | 28.4 | 10,700 | 6.0 | 2.7 | 6.9 | - | ||
| C4 | 9/1/2020 | 1130 | 1.2 | 28.9 | 4,080 | 2.2 | 7.9 | 7.9 | 1.4 |
| 1131 | 8.1 | 28.9 | 4,090 | 2.2 | 7.8 | 7.7 | - | ||
| 1132 | 15.9 | 28.1 | 18,800 | 11.1 | 1.4 | 6.9 | - | ||
| C7 | 9/1/2020 | 1201 | 1.6 | 28.7 | 6,410 | 3.5 | 7.6 | 7.8 | 1.1 |
| 1202 | 9.1 | 28.6 | 6,430 | 3.5 | 7.4 | 7.5 | - | ||
| 1203 | 15.1 | 28.5 | 11,900 | 6.8 | 1 | 6.9 | - | ||
| H11 | 9/1/2020 | 1301 | 1.3 | 29 | 4,520 | 2.4 | 7.4 | 7.7 | 1 |
| 1302 | 7.7 | 29 | 4,530 | 2.4 | 7.4 | 7.7 | - | ||
| 1303 | 14.4 | 29 | 4,550 | 2.4 | 7.3 | 7.7 | - |
Table 2.10 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of September 14–18, 2020, week 20 after spillway was closed
| Station Abbreviation | Date | Time (CST) | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| SJ | 9/17/2020 | 1401 | 0.17 | 27 | 25,300 | 15.4 | 6.8 | 7.5 | 0.7 |
| 1402 | 1.53 | 26.3 | 25,200 | 15.3 | 6.7 | 7.5 | - | ||
| 1403 | 3.06 | 26.3 | 25,300 | 15.4 | 6.6 | 7.5 | - | ||
| MB2 | 9/17/2020 | 1000 | 0.32 | 25.6 | 27,800 | 17.1 | 6.4 | 7.7 | 0.7 |
| 1001 | 1.3 | 25.5 | 27,800 | 17.1 | 6.4 | 7.6 | - | ||
| 1002 | 2.63 | 25.6 | 28,500 | 17.5 | 6.1 | 7.5 | - | ||
| MB1 | 9/17/2020 | 1015 | 0.29 | 25.5 | 29,000 | 17.9 | 6.8 | 7.8 | 1 |
| 1016 | 1.55 | 25.5 | 29,000 | 17.9 | 6.7 | 7.8 | - | ||
| 1017 | 3.41 | 25.5 | 29,600 | 18.3 | 6.5 | 7.7 | - | ||
| MB | 9/17/2020 | 1031 | 0.51 | 25.7 | 32,000 | 19.9 | 6.6 | 7.8 | 0.8 |
| 1032 | 2.54 | 25.7 | 32,100 | 20.0 | 6.4 | 7.8 | - | ||
| 1033 | 5.07 | 25.9 | 34,300 | 21.5 | 5.6 | 7.8 | - | ||
| GP2 | 9/17/2020 | 1045 | 1.3 | 25.8 | 33,200 | 20.8 | 6.9 | 7.9 | 0.7 |
| 1046 | 6.5 | 25.8 | 33,300 | 20.8 | 6.8 | 7.9 | - | ||
| 1047 | 10.6 | 25.7 | 35,300 | 22.2 | 6.1 | 7.8 | - | ||
| GP1 | 9/17/2020 | 1100 | 1.7 | 25.9 | 34,800 | 21.8 | 6.9 | 7.9 | 0.7 |
| 1101 | 6.5 | 25.7 | 35,300 | 22.2 | 6.6 | 7.8 | - | ||
| 1102 | 13.3 | 25.6 | 36,100 | 22.7 | 6.4 | 7.8 | - | ||
| GP | 9/17/2020 | 1115 | 0.6 | 25.4 | 36,600 | 23.1 | 6.6 | 7.8 | 0.3 |
| 1116 | 4.3 | 25.4 | 36,700 | 23.2 | 6.6 | 7.8 | - | ||
| 1117 | 8.8 | 25.3 | 37,100 | 23.5 | 6.6 | 7.8 | - | ||
| LB | 9/17/2020 | 1301 | 0.2 | 26.6 | 15,600 | 9.1 | 8.9 | 7.9 | 1 |
| 1302 | 4.9 | 26 | 16,800 | 9.8 | 9 | 8 | - | ||
| 1303 | 9.5 | 25.7 | 18,700 | 11.0 | 7.7 | 7.9 | - | ||
| PP | 9/17/2020 | 1230 | 1.6 | 26.3 | 22,700 | 13.7 | 8.5 | 7.9 | 0.5 |
| 1231 | 5.2 | 26.1 | 22,900 | 13.8 | 8.3 | 7.9 | - | ||
| 1232 | 10.4 | 25.7 | 23,300 | 14.1 | 7.4 | 7.8 | - | ||
| TM | 9/17/2020 | 1130 | 1.3 | 25.9 | 30,700 | 19.1 | 6.7 | 7.7 | 0.3 |
| 1131 | 3.9 | 25.7 | 30,700 | 19.1 | 6.6 | 7.7 | - | ||
| 1132 | 6.2 | 25.6 | 30,700 | 19.1 | 6.6 | 7.7 | - |
Table 2.11 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of September 28 – October 2, 2020, week 22 after spillway was closed
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 9/28/2020 | 0801 | 1.13 | 24.7 | 5,260 | 2.8 | 8.9 | 7.3 | 0.9 |
| 0802 | 7.51 | 24.6 | 5,290 | 2.9 | 8.7 | 7 | - | ||
| 0803 | 15.9 | 23.8 | 5,880 | 3.2 | 5.7 | 6.7 | - | ||
| C2 | 9/28/2020 | 0901 | 0.9 | 24.5 | 5,710 | 3.1 | 9.1 | 7.7 | 1.1 |
| 0902 | 8.1 | 24.4 | 5,710 | 3.1 | 8.8 | 7.5 | - | ||
| 0903 | 16.1 | 23.8 | 6,000 | 3.3 | 6.6 | 7.3 | - | ||
| C4 | 9/28/2020 | 0930 | 0.4 | 25.3 | 6,190 | 3.4 | 9.5 | 8.2 | 1 |
| 0931 | 8.4 | 24.9 | 6,490 | 3.5 | 8.7 | 7.7 | - | ||
| 0932 | 17 | 23.7 | 9,400 | 5.3 | 4.4 | 7.3 | - | ||
| C7 | 9/28/2020 | 1001 | 0.6 | 26 | 9,240 | 5.2 | 10.2 | 8.4 | 1.5 |
| 1002 | 8.4 | 25.3 | 9,290 | 5.2 | 9.7 | 8.2 | - | ||
| 1003 | 16 | 23.8 | 11,100 | 6.3 | 3.8 | 7.4 | - | ||
| H11 | 9/28/2020 | 1131 | 0.8 | 25.4 | 7,830 | 4.3 | 8.7 | 7.9 | 1.3 |
| 1132 | 8.4 | 25.2 | 7,830 | 4.3 | 8.6 | 7.9 | - | ||
| 1133 | 17.1 | 25.2 | 7,830 | 4.3 | 8.5 | 7.9 | - |
Table 2.12 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of October 26-30, 2020, week 26 after spillway was closed
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 10/26/2020 | 0801 | 1.7 | 23.3 | 6,000 | 3.3 | 8.1 | 7 | 0.9 |
| 0802 | 9.9 | 23.3 | 6,000 | 3.3 | 8.1 | 7 | - | ||
| 0803 | 14.8 | 23.3 | 6,000 | 3.3 | 8 | 6.8 | - | ||
| C2 | 10/26/2020 | 0901 | 1.6 | 23.3 | 4,180 | 2.3 | 8 | 7 | 1 |
| 0902 | 9 | 23.3 | 6,780 | 3.7 | 7.9 | 6.9 | - | ||
| 0903 | 17.7 | 23.3 | 6,780 | 3.7 | 7.9 | 6.9 | - | ||
| C4 | 10/26/2020 | 0930 | 2.2 | 23.5 | 7,720 | 4.3 | 7.1 | 8 | 0.7 |
| 0931 | 8.9 | 23.5 | 7,720 | 4.3 | 7 | 8 | - | ||
| 0932 | 17.2 | 23.5 | 7,730 | 4.3 | 6.9 | 7.9 | - | ||
| C7 | 10/26/2020 | 1001 | 2 | 23.6 | 8,570 | 4.8 | 7.9 | 7.1 | 0.75 |
| 1002 | 8.9 | 23.6 | 8,570 | 4.8 | 7.9 | 7 | - | ||
| 1003 | 17.4 | 23.6 | 8,570 | 4.8 | 7.8 | 6.8 | - | ||
| H11 | 10/26/2020 | 1131 | 1.7 | 22.8 | 8,350 | 4.7 | 7.8 | 7 | 0.85 |
| 1132 | 6.7 | 22.8 | 8,450 | 4.7 | 7.8 | 6.9 | - | ||
| 1133 | 1.6 | 22.8 | 8,540 | 4.8 | 7.9 | 6.7 | - |
Table 2.13 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of November 2-6, 2020, week 27 after spillway was closed
| Station Abbreviation | Date | Time (CST) | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| SJ | 11/10/2020 | 1401 | 1.8 | 21.3 | 28,100 | 17.3 | 8.3 | 8 | 1 |
| 1402 | 5.3 | 20.6 | 29,400 | 18.2 | 8.1 | 7.9 | - | ||
| 1403 | 10 | 20.7 | 29,600 | 18.3 | 8.4 | 7.9 | - | ||
| MB2 | 11/10/2020 | 1201 | 2.1 | 20.9 | 37,200 | 23.6 | 7.6 | 7.7 | 1 |
| 1202 | 5.1 | 20.9 | 37,200 | 23.6 | 7.5 | 7.7 | - | ||
| 1203 | 10.9 | 20.8 | 37,200 | 23.6 | 7.4 | 7.5 | - | ||
| MB1 | 11/10/2020 | 1146 | 1.9 | 20.7 | 36,400 | 23.0 | 7.8 | 7.9 | 1.4 |
| 1147 | 5.9 | 20.7 | 36,500 | 23.1 | 7.7 | 7.9 | - | ||
| 1148 | 13.4 | 20.6 | 37,200 | 23.6 | 7.5 | 7.9 | - | ||
| MB | 11/10/2020 | 1131 | 1.9 | 20.8 | 36,300 | 23.0 | 7.9 | 8 | 1.5 |
| 1132 | 8 | 20.4 | 37,000 | 23.5 | 7.2 | 7.9 | - | ||
| 1133 | 16.4 | 20.5 | 38,400 | 24.4 | 7.3 | 7.9 | - | ||
| GP2 | 11/10/2020 | 1101 | 2.1 | 20.9 | 37,800 | 24.0 | 8 | 8 | 1.3 |
| 1102 | 5.8 | 20.8 | 37,800 | 24.0 | 7.7 | 8 | - | ||
| 1103 | 10.7 | 20.6 | 38,400 | 24.4 | 7.3 | 8 | - | ||
| GP1 | 11/10/2020 | 1046 | 1.9 | 21 | 40,800 | 26.2 | 8 | 8 | 1.5 |
| 1047 | 7.5 | 20.8 | 40,900 | 26.2 | 7.8 | 8 | - | ||
| 1048 | 13.7 | 20.7 | 41,600 | 26.6 | 7.7 | 8 | - | ||
| GP | 11/10/2020 | 1031 | 1.8 | 21.6 | 43,000 | 27.7 | 7.9 | 8.1 | 0.4 |
| 1032 | 5.5 | 21.3 | 43,100 | 27.8 | 7.7 | 8.1 | - | ||
| 1033 | 10.9 | 21.2 | 43,200 | 27.8 | 7.6 | 8.1 | - | ||
| LB | 11/10/2020 | 1301 | 1.8 | 21 | 15,200 | 8.9 | 9.7 | 8.1 | 0.9 |
| 1302 | 5.3 | 20.9 | 15,200 | 8.9 | 9.6 | 8.1 | - | ||
| 1303 | 10.2 | 20.6 | 15,300 | 8.9 | 9 | 8 | - | ||
| PP | 11/10/2020 | 1231 | 1.7 | 21.4 | 23,700 | 14.4 | 8.2 | 8 | 0.7 |
| 1232 | 6.1 | 21.1 | 24,400 | 14.8 | 8.1 | 8 | - | ||
| 1233 | 12.2 | 21 | 24,700 | 15.1 | 8.1 | 8 | - | ||
| TM | 11/10/2020 | 1216 | 1.5 | 21.5 | 32,000 | 20.0 | 8.1 | 8 | 0.8 |
| 1217 | 4.1 | 21.5 | 32,000 | 20.0 | 8.1 | 8 | - | ||
| 1218 | 7.3 | 21.5 | 32,200 | 20.1 | 8.1 | 8 | - |
Table 2.14 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of November 16-20, 2020, week 29 after spillway was closed
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 11/16/2020 | 1001 | 2.80 | 19.7 | 6,440 | 3.5 | 8.8 | 7.4 | 1.2 |
| 1002 | 9.20 | 19.7 | 6,430 | 3.5 | 8.8 | 7.4 | - | ||
| 1003 | 17.40 | 19.7 | 6,440 | 3.5 | 8.8 | 7.4 | - | ||
| C2 | 11/16/2020 | 0901 | 2.20 | 19.8 | 7,730 | 4.3 | 8.9 | 7.5 | 0.9 |
| 0902 | 9.40 | 19.8 | 7,730 | 4.3 | 8.9 | 7.4 | - | ||
| 0903 | 17.50 | 19.7 | 7,730 | 4.3 | 8.9 | 7.4 | - | ||
| C4 | 11/16/2020 | 1030 | 2.20 | 19.8 | 7,560 | 4.2 | 8.9 | 7.5 | 0.65 |
| 1031 | 8.60 | 19.8 | 7,560 | 4.2 | 8.9 | 7.4 | - | ||
| 1032 | 18.60 | 19.8 | 7,560 | 4.2 | 8.9 | 7.4 | - | ||
| C7 | 11/16/2020 | 1201 | 2.80 | 19.8 | 7,980 | 4.4 | 8.9 | 7.4 | 0.6 |
| 1202 | 8.20 | 19.8 | 7,980 | 4.4 | 8.9 | 7.4 | - | ||
| 1203 | 18.30 | 19.8 | 7,980 | 4.4 | 8.7 | 7.2 | - | ||
| H11 | 11/16/2020 | 1101 | 2.70 | 19.4 | 9,150 | 5.1 | 8.6 | 7.4 | 0.6 |
| 1102 | 7.30 | 19.5 | 9,370 | 5.2 | 8.5 | 7.3 | - | ||
| 1103 | 15.10 | 19.7 | 9,700 | 5.5 | 8.3 | 7.2 | - |
Table 2.15 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2021.
Field data for week of Aug 13, 2021 - Aug 20, 2021, no spillway operation in 2021
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 8/13/2021 | 0900 | 0.50 | 30.5 | 725 | 0.4 | 7.6 | 7 | 1.5 |
| 0901 | 7.20 | 30.1 | 723 | 0.4 | 7.7 | 7.1 | - | ||
| 0902 | 14.40 | 30 | 723 | 0.4 | 7.7 | 7.2 | - | ||
| C2 | 8/13/2021 | 1001 | 0.50 | 30.2 | 825 | 0.4 | 6.9 | 7.1 | 1.2 |
| 1002 | 7.10 | 30 | 824 | 0.4 | 6.9 | 7.1 | - | ||
| 1003 | 14.00 | 29.9 | 823 | 0.4 | 6.8 | 7.2 | - | ||
| C4 | 8/13/2021 | N/A | - | - | - | - | - | - | - |
| C7 | 8/13/2021 | 1201 | 0.50 | 30.1 | 1,560 | 0.7 | 7.2 | 6.8 | 1.1 |
| 1202 | 7.20 | 30 | 1,550 | 0.7 | 6.8 | 6.8 | - | ||
| 1203 | 15.40 | 29.9 | 1,550 | 0.7 | 6.9 | 6.8 | - | ||
| H11 | 8/12/2021 | 1101 | 0.90 | 30.4 | 1,370 | 0.7 | 7.8 | 7.2 | 1.3 |
| 1102 | 6.90 | 30.2 | 1,360 | 0.7 | 7.2 | 7.2 | - | ||
| 1103 | 11.70 | 30.1 | 1,360 | 0.7 | 6.6 | 7.2 | - |
Table 2.16 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2021.
Field data for week of Sept 27, 2021 - Oct 1, 2021, no spillway operation in 2021
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 9/27/2021 | 0730 | 0.50 | 24.9 | 1,950 | 1.0 | 7.3 | 7.4 | 0.8 |
| 0731 | 7.20 | 24.9 | 1,950 | 1.0 | 7.3 | 7.3 | - | ||
| 0732 | 14.40 | 24.8 | 1,950 | 1.0 | 7.3 | 7.3 | - | ||
| C2 | 9/27/2021 | 0801 | 0.50 | 25.2 | 3,390 | 1.8 | 8.1 | 7.8 | 0.6 |
| 0802 | 7.10 | 25.2 | 3,390 | 1.8 | 8.1 | 7.7 | - | ||
| 0803 | 14.00 | 25.2 | 3,400 | 1.8 | 8.1 | 7.6 | - | ||
| C4 | 9/27/2021 | 0830 | 0.50 | 25.4 | 4,260 | 2.3 | 7.9 | 7.8 | 0.55 |
| 0831 | 7.50 | 25.4 | 4,260 | 2.3 | 7.9 | 7.8 | - | ||
| 0832 | 14.80 | 25.4 | 4,260 | 2.3 | 7.9 | 7.8 | - | ||
| C7 | 9/27/2021 | 0901 | 0.50 | 24.8 | 3,370 | 1.7 | 7 | 7.6 | 0.55 |
| 0902 | 7.20 | 24.8 | 3,370 | 1.7 | 7.6 | 7.6 | - | ||
| 0903 | 15.40 | 24.8 | 3,360 | 1.7 | 7.6 | 7.6 | - | ||
| H11 | 9/24/2021 | 1101 | 1.10 | 25.2 | 3,320 | 1.7 | 7.8 | 7.5 | 0.6 |
| 1102 | 5.90 | 24.9 | 3,320 | 1.7 | 7.7 | 7.4 | - | ||
| 1103 | 11.90 | 24.7 | 3,310 | 1.7 | 7.5 | 7.2 | - | ||
| MB2 | 9/27/2021 | 1051 | 1.6 | 26.1 | 4,150 | 2.1 | 8.2 | 7.9 | 0.65 |
| 1052 | 5.3 | 25.3 | 8,920 | 4.9 | 5.1 | 7.3 | - | ||
| 1053 | 9.3 | 25.2 | 11,300 | 6.4 | 4.2 | 7.3 | - | ||
| MB1 | 9/27/2021 | 1041 | 1.5 | 25.6 | 3,960 | 2.1 | 8.5 | 8 | 0.8 |
| 1042 | 5.4 | 24.9 | 4,820 | 2.6 | 7.1 | 7.6 | - | ||
| 1043 | 12.3 | 25.1 | 11,400 | 6.5 | 3.9 | 7.2 | - | ||
| MB | 9/27/2021 | 1031 | 2.5 | 25.4 | 7,870 | 4.3 | 8.8 | 8.3 | 0.9 |
| 1032 | 7.4 | 25.1 | 10,900 | 6.2 | 6.3 | 7.8 | - | ||
| 1033 | 14.8 | 25.3 | 17,300 | 10.1 | 4.1 | 7.4 | - | ||
| GP2 | 9/27/2021 | 1151 | 1.8 | 25.5 | 8,450 | 4.6 | 8.7 | 8.3 | 1 |
| 1152 | 6.8 | 25.4 | 9,710 | 5.4 | 8 | 8.2 | - | ||
| 1153 | 11 | 25.3 | 17,600 | 10.3 | 6 | 7.8 | - | ||
| GP1 | 9/27/201 | 1141 | 1.4 | 25.3 | 13,600 | 7.8 | 8 | 8.1 | 1.3 |
| 1142 | 7.6 | 25.1 | 14,200 | 8.2 | 6.6 | 8 | - | ||
| 1143 | 13.8 | 25.4 | 23,700 | 14.2 | 4.9 | 7.7 | - | ||
| GP | 9/7/2021 | 1131 | 2 | 25.1 | 10,700 | 6.0 | 8.1 | 8.2 | 0.8 |
| 1132 | 5.2 | 25.2 | 11,700 | 6.6 | 7.7 | 8.1 | - | ||
| 1133 | 10.5 | 25.3 | 12,900 | 7.4 | 7.4 | 8 | - |
Table 2.17 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2021.
Field data for week of Oct 25, 2021 - Oct 29, 2021, no spillway operation in 2021
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 10/26/2021 | 1115 | 2.00 | 24.5 | 3,390 | 1.8 | 8 | 7.7 | 0.4 |
| 1116 | 8.00 | 24.3 | 3,390 | 1.8 | 7.7 | 7.6 | - | ||
| 1117 | 16.00 | 24.2 | 3,390 | 1.8 | 7.7 | 7.7 | - | ||
| C2 | 10/26/2021 | 1101 | 2.32 | 24.2 | 3,250 | 1.8 | 7.8 | 7.7 | 0.35 |
| 1102 | 8.42 | 24.1 | 3,250 | 1.8 | 7.7 | 7.7 | - | ||
| 1103 | 16.90 | 24.1 | 3,250 | 1.8 | 7.8 | 7.8 | - | ||
| C4 | 10/26/2021 | 1030 | 1.98 | 24.2 | 3,340 | 1.8 | 8.1 | 7.8 | 0.3 |
| 1031 | 8.33 | 24.1 | 3,340 | 1.8 | 8 | 7.8 | - | ||
| 1032 | 18.10 | 24.1 | 3,340 | 1.8 | 7.9 | 7.8 | - | ||
| C7 | 10/26/2021 | 1001 | 2.28 | 23.8 | 2,680 | 1.5 | 7.4 | 7.6 | 0.2 |
| 1002 | 9.16 | 23.8 | 2,680 | 1.5 | 7.4 | 7.7 | - | ||
| 1003 | 17.50 | 23.8 | 2,680 | 1.5 | 7.4 | 7.7 | - | ||
| H11 | 10/28/2021 | 0930 | 2.70 | 23.1 | 2,610 | 1.5 | 8 | 7.2 | 0.1 |
| 0931 | 6.39 | 23.1 | 2,610 | 1.5 | 8 | 7.1 | - | ||
| 0932 | 13.40 | 23.1 | 2,610 | 1.5 | 8 | 6.9 | - | ||
| MB2 | 10/25/2021 | 1410 | 1.2 | 25.1 | 12,000 | 6.8 | 7.3 | 7.7 | 1 |
| 1411 | 4.44 | 24.8 | 12,500 | 7.2 | 7.2 | 7.7 | - | ||
| 1412 | 9.38 | 24.7 | 13,200 | 7.6 | 7.1 | 7.7 | - | ||
| MB1 | 10/25/2021 | 1400 | 1.52 | 25.2 | 10,400 | 5.8 | 7.6 | 7.7 | 1 |
| 1401 | 5.52 | 24.2 | 14,200 | 8.4 | 6.7 | 7.6 | - | ||
| 1402 | 10.2 | 24.2 | 16,000 | 9.5 | 6.4 | 7.6 | - | ||
| MB | 10/25/2021 | 1301 | 1.95 | 25.5 | 14,700 | 8.4 | 7.7 | 7.9 | 0.9 |
| 1302 | 7.45 | 24.4 | 17,800 | 10.6 | 7.3 | 7.9 | - | ||
| 1303 | 13.4 | 24.2 | 18,400 | 11.1 | 7.2 | 7.9 | - | ||
| GP2 | 10/25/2021 | 1230 | 1.55 | 24.8 | 19,600 | 11.7 | 7.5 | 8 | 0.8 |
| 1231 | 5.36 | 24.8 | 19,600 | 11.7 | 7.5 | 8 | - | ||
| 1232 | 11.3 | 24.7 | 19,700 | 11.8 | 7.4 | 8 | - | ||
| GP1 | 10/25/2021 | 1200 | 1.59 | 25.6 | 16,800 | 9.7 | 7.8 | 8 | 1.2 |
| 1201 | 7.66 | 24.4 | 22,800 | 13.9 | 7 | 7.9 | - | ||
| 1202 | 13.2 | 24.4 | 23,000 | 14.1 | 7 | 7.9 | - | ||
| GP | 10/25/2021 | 1101 | 1.4 | 24.9 | 19,900 | 11.9 | 7 | 7.9 | 0.55 |
| 1102 | 4.82 | 24.8 | 20,000 | 12 | 6.9 | 7.9 | -- | ||
| 1103 | 10.8 | 24.8 | 20,000 | 12 | 6.8 | 7.8 | -- |
Table 2.18 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2021.
Field data for week of Dec 6, 2021 - Dec 10, 2021, no spillway operation in 2021
| Station Abbreviation | Date | Time | Sample Depth (ft) | Water Temperature (°C) | Specific Conductance (µS/cm) | Salinity (ppt) | Dissolved Oxygen (mg/L) | pH (units) | Secchi Depth (m) |
|---|---|---|---|---|---|---|---|---|---|
| C1 | 12/7/2021 | 1045 | 2.53 | 17.1 | 2,940 | 1.6 | 10.3 | 7.9 | 0.9 |
| 1046 | 7.59 | 17.1 | 2,940 | 1.6 | 10.2 | 8 | - | ||
| 1047 | 16.00 | 17.1 | 2,940 | 1.6 | 10.2 | 8 | - | ||
| C2 | 12/7/2021 | 1031 | 2.45 | 17.2 | 3,010 | 1.6 | 10.4 | 8.1 | 0.7 |
| 1032 | 7.72 | 17.2 | 3,010 | 1.6 | 10.4 | 8.1 | - | ||
| 1033 | 17.60 | 17.2 | 3,010 | 1.6 | 10.3 | 8 | - | ||
| C4 | 12/7/2021 | 1020 | 2.78 | 16.9 | 2,760 | 1.5 | 9.9 | 7.9 | 0.5 |
| 1021 | 8.66 | 16.9 | 2,760 | 1.5 | 9.9 | 7.9 | - | ||
| 1022 | 19.10 | 16.9 | 2,760 | 1.5 | 9.8 | 7.9 | - | ||
| C7 | 12/7/2021 | 1001 | 2.62 | 17 | 2,020 | 1.0 | 9.6 | 7.9 | 0.3 |
| 1002 | 8.48 | 17 | 2,020 | 1.0 | 9.6 | 7.9 | - | ||
| 1003 | 17.50 | 17 | 2,020 | 1.0 | 9.6 | 8 | - | ||
| H11 | 12/7/2021 | 0901 | 2.76 | 18 | 3,250 | 1.8 | 9.4 | 8 | 0.7 |
| 0902 | 8.74 | 18.3 | 4,720 | 2.5 | 9.2 | 8.1 | - | ||
| 0903 | 17.70 | 18.4 | 5,750 | 3.1 | 9.1 | 8.1 | - |
*USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
- Overview
The Bonnet Carré Spillway, located about 28 miles northwest of New Orleans, Louisiana, was constructed in the early 1930s as part of an integrated flood-control structure for the lower Mississippi River Plain. The spillway is designed to divert water from the Mississippi River into Lake Pontchartrain, thus relieving pressure on levees downstream. Opening of the spillway occurs when measured streamflow in the Mississippi River at New Orleans exceeds 1.25 million cubic feet per second, which normally occurs late in the spring season. Over the approximately 90 years since its construction, the spillway has been opened only twelve times; however, in 2019, it was opened twice. Monitoring the quality of surface waters receiving diverted Mississippi River water including Lake(s) Pontchartrain and Borgne and the Mississippi Sound is of vital importance to public- and natural resource managers in Louisiana and Mississippi. These bodies of water provide crucial habitat for fish, crabs and other shellfish, seagrasses, and marine mammals, such as dolphins and manatees. Coastal waters are also used for recreation and commercial fishing.
The U.S. Geological Survey (USGS), Lower Mississippi-Gulf Water Science Center (LMG), in cooperation with the U.S. Army Corp of Engineers (USACE) New Orleans District, has sampled water from Lake Pontchartrain, Lake Borgne, and the western Mississippi Sound prior, during, and after each spillway opening from 2008 to present. In 2020, discrete water-quality samples are being collected at all stations in Lake(s) Pontchartrain and Borgne and the western Mississippi Sound (map thumbnail) except at Rigolets at Hwy 90 near Slidell, LA (RIG) and East Pearl River at CSX Railroad near Claiborne, MS (EPR). Samples are analyzed for major ions, nutrients, inorganic plus organic particulate carbon, total suspended solids, chlorophyll a, phytoplankton composition, and algal toxins. Euphotic depths are determined from Secchi depth readings and then used to guide the sample collection depths for chlorophyll, phytoplankton, and algal toxins. Currently, the USGS-LMG also measures continuous water quality (stage, salinity, and temperature) at five stations in the western Mississippi Sound (Table 1).
A multi-parameter data sonde is used at each of the sites at the time of sample collection to measure water temperature, specific conductance, salinity, dissolved oxygen, and pH typically at 0.5 meters above the bottom depth, mid-depth, and 0.5 meters below the water surface to document any salinity or dissolved-oxygen stratifications within the water column. These field data are useful in monitoring changes in salinity and stratification that influence biological processes in the lake and sound waters.
USACE Spillway Operation Information
Sources/Usage: Public Domain.Table 1 - U.S. Geological Survey routine and synoptic water-quality sampling stations in
Lakes Pontchartrain/Borgne and the western Mississippi Sound.
[click on station type for a link to the data from the USGS National Water Information System web interface (waterdata.usgs.gov); 2020-21 field parameters are shown in Tables 2.1-2.16]
USGS Station ID USGS Station Name Latitude Longitude Station Abbreviation Station Type Field Parameters Laboratory Water Quality 300115090245000 Bonnet Carré Spillway at US Hwy 61 near Norco, LA 30.02083 -90.413889 BC Discrete X X 301853090060700 Lake Pontchartrain at Causeway Bridge near Mandeville 30.31472 -90.101944 C1 Discrete X X 301528090064600 Lake Pontchartrain at Causeway Bridge near Mandeville, LA 30.25778 -90.112778 C2 Discrete X X 301200090072400 Lake Pontchartrain at Crossover 4 near Mandeville, LA 30.19964 -90.12275 C4 Discrete X 300412090084300 Lake Pontchartrain at Causeway Bridge near Metairie 30.07 -90.145278 C7 Discrete X X 301050089511600 Lake Pontchartrain at Hwy 11 Causeway near Slidell 30.18056 -89.854444 H11 Discrete X X 300218089374500 Lake Borgne 5.5 miles east of Alligator Point, LA 30.03833 -89.629167 LB Discrete X X 300454089284200 Western Mississippi Sound near Le Petit Pass Island, LA 30.08166 -89.47839 PP Discrete X 300233089224200 Western Mississippi Sound near Three Mile Bay, LA 30.04236 -89.37823 TM Discrete X 301001089442600 Rigolets at Hwy 90 near Slidell, LA 30.16694 -89.74056 RIG Continuous 301141089320300 E. Pearl River at CSX RR near Claiborne, MS 30.19472 -89.53417 EPR Continuous 301104089253400 Mississippi Sound at St. Joseph Island Light, MS 30.19083 -89.42222 SJ Continuous X X 301429089145600 Mississippi Sound at Merrill Shell Bank Light, MS 30.23806 -89.242778 MB Continuous X X 300722089150100 Mississippi Sound near Grand Pass, LA 30.12278 -89.2502778 GP Continuous X X 301746089143500 MB2, 1 mile south of Pass Christian, MS 30.29608 -89.24317 MB2 Discrete X 301636089144400 MB1, 2.5 miles north of Merrill Bank, MS 30.27665 -89.24555 MB1 Discrete X 301252089150400 GP2, 6 miles north of Grand Pass, LA 30.21452 -89.25105 GP2 Discrete X 301047089150200 GP1, 3 miles north of Grand Pass, LA 30.1796 -89.25063 GP1 Discrete X Table 2.1 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of April 6–10, 2020, spillway week 1*
Station Abbreviation Date Time (CST) Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) BC 4/9/2020 1131 0.9 16.6 315 0.1 9.2 7.7 0.4 1132 3.9 16.6 315 0.1 9.2 7.7 - 1133 8.8 16.6 315 0.1 9.2 7.7 - C1 4/8/2020 1001 0.9 23.9 676 0.3 8.7 7.8 0.55 1002 7.4 23.6 688 0.3 8.3 7.6 - 1003 15.1 23.6 728 0.3 8.2 7.6 - C2 4/8/2020 1101 0.7 23.9 774 0.3 8.7 7.7 0.5 1102 8.1 23.4 791 0.3 7.4 7.4 - 1103 15.9 23.5 802 0.3 7.3 7.3 - C4 4/8/2020 1130 0.2 24.2 898 0.4 8.9 7.9 0.7 1131 8.6 24.2 976 0.4 8.2 7.4 - 1132 16.7 23.3 880 0.4 8.1 7.3 - C7 4/8/2020 1201 0.8 23.5 1,170 0.6 8.4 7.7 1.05 1202 7.6 23.4 1,170 0.6 8.4 7.6 - 1203 14.5 23.4 1,180 0.6 8.2 7.5 - H11 4/9/2020 1131 0.9 24.8 1,130 0.6 8.1 7.8 0.4 1132 6.4 24.8 1,130 0.6 8.1 7.8 - 1133 13.1 24.8 1,130 0.6 8.1 7.6 - Table 2.2 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of April 20–24, 2020, spillway week 3*
Station Abbreviation Date Time (CST) Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) BC 4/16/2020 1000 1.5 16.9 320 0.0 8.6 7.7 0.7 SJ 4/20/2020 1201 0.3 22.9 2,380 1.2 8.2 7.4 0.25 1202 4.8 22.7 2,440 1.2 8.1 7.3 - 1203 9.8 22.4 2,840 1.5 8 7.3 - MB2 4/20/2020 0945 1.5 22 12,100 6.9 8.7 7.8 0.8 0946 4.4 21.8 15,700 9.2 8.2 7.7 - 0947 9.3 20.9 26,000 16.0 5.1 7.3 - MB1 4/20/2020 0930 0.9 22.2 10,500 6.0 9.2 8 0.65 0932 5.7 21.9 11,900 6.8 7.8 7.7 - 0932 11.6 21.1 23,400 14.0 5.7 7.4 - MB 4/20/2020 1131 1.1 21.9 8,290 4.6 8.3 7.7 0.7 1132 7.3 21.8 8,270 4.6 8.1 7.7 - 1133 14.8 21 24,300 15.0 6.5 7.3 - GP2 4/20/2020 1015 0.7 22 7,970 4.0 8.9 8 0.7 1016 5.7 21.9 7,990 4.0 8.4 7.9 - 1017 11.5 20.9 24,900 15.0 5.9 7.4 - GP1 4/20/2020 1000 1.3 21.9 7,080 4.0 8.6 7.9 0.7 1001 6.7 21.7 7,160 4.0 8.2 8 - 1002 13.1 21 34,800 22.0 6.4 7.7 - GP 4/20/2020 1031 1.2 22.3 10,900 8.8 8.8 7.8 0.6 1032 3.6 22.2 10,900 8.6 8.6 7.9 - 1033 9.3 21.9 11,300 8.2 8.2 7.8 - LB 4/21/2020 1031 0.7 23.1 1,370 0.7 9.5 8.3 0.25 1032 6.5 22.2 1,360 0.7 8.5 7.8 - 1033 11.2 22.2 1,370 0.7 8.4 7.9 - PP 4/20/2020 1400 0.5 23 2,070 1.0 8.9 7.8 0.2 1401 5.6 22.3 2,070 1.0 8.6 7.7 - 1402 11.3 22.1 2,070 1.0 8.6 7.7 - TM 4/20/2020 1250 0.3 23.4 2,850 1.9 9.1 8 0.2 1251 2.8 23.1 2,880 2.0 8.9 7.9 - 1252 5.9 22.5 3,230 2.0 8.6 7.8 - Table 2.3 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of April 27 – May 1, 2020, spillway week 4*
Station Abbreviation Date Time (CST) Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 4/28/2020 1001 1 22.6 857 0.4 12.2 7.5 0.6 1002 8.1 22.7 859 0.4 8.3 7.4 - 1003 15.6 22.7 859 0.4 8.2 7.3 - C2 4/28/2020 1101 0.99 22.3 860 0.4 8.5 7.5 0.55 1102 9.1 22.4 853 0.4 8.4 7.4 - 1103 15.9 22.4 853 0.4 8 7.3 - C4 4/28/2020 N/A - - - - - - - C7 4/28/2020 1201 1.9 21.7 343 0.2 9 7.9 0.75 1202 8.8 21.6 343 0.2 8.9 7.9 - 1203 16.1 21.6 343 0.2 8.8 7.8 - H11 4/29/2020 1131 1.5 22.4 437 0.2 8.5 8 0.25 1132 6.5 22.4 437 0.2 8.5 7.9 - 1133 12.9 21.4 437 0.2 8.5 7.9 - Table 2.4 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of May 25–29, 2020, week 4 after spillway was closed
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 5/26/2020 1001 2.1 27 944 0.5 7.4 7.5 0.7 1002 9.7 26.9 943 0.5 7.4 7.5 - 1003 16 26.9 943 0.5 7.4 7.5 - C2 5/26/2020 1101 0.7 26.8 686 0.3 7.7 7.5 0.7 1102 8.1 26.7 683 0.3 7.5 7.4 - 1103 16.5 26.6 711 0.3 7.4 7.3 - C4 5/26/2020 1131 1.2 26.9 814 0.4 7.8 7.6 0.55 1132 8.7 26.7 814 0.4 7.6 7.4 - 1133 17.8 26.6 814 0.4 7.5 7.3 - C7 5/26/2020 1201 1.3 27.1 547 0.3 7.6 7.5 0.7 1202 8.8 26.7 548 0.3 7.4 7.5 - 1203 16.6 26.7 548 0.3 7.4 7.4 - H11 5/27/2020 1131 1.9 27.6 438 0.2 7.9 7.8 0.2 1132 8.6 27.1 619 0.3 7.8 7.8 - 1133 15.6 26.9 869 0.4 7.6 7.7 - Table 2.5 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of June 1–5, 2020, week 5 after spillway was closed
Station Abbreviation Date Time (CST) Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) SJ 6/2/2020 1401 1 27.6 10,100 5.7 7.2 7.7 0.5 1402 6.5 27.6 10,100 5.7 7.2 7.7 - 1403 11 27.6 10,100 5.7 7.2 7.7 - MB2 6/2/2020 1100 1.2 27.7 17,800 10.5 7.5 8.1 1.1 1101 6.3 27.7 18,100 10.7 7 8 - 1102 10.1 27.8 18,800 11.1 6.3 7.8 - MB1 6/2/2020 1115 0.8 27.7 18,100 10.7 7.9 8.2 1.3 1116 4.6 27.7 18,200 10.7 7.6 8.1 - 1117 9.1 27.7 19,100 11.3 7.1 8.1 - MB 6/2/2020 1131 1.3 27.7 17,800 10.5 7.4 8.1 1.3 1132 4.3 27.6 17,800 10.5 7.1 8 - 1133 15.2 27.5 22,700 13.6 3.3 7.7 - GP2 6/2/2020 1000 0.6 27.8 20,100 11.9 7.6 8.2 1.15 1001 6.1 27.8 20,300 12.1 7.3 8.2 - 1002 12.1 27.4 23,500 14.2 4.2 7.8 - GP1 6/2/2020 1015 1.6 27.7 20,900 12.5 8 8.3 0.95 1016 6.5 27.6 23,600 14.2 7.4 8.3 - 1017 13.6 27.6 25,800 15.7 6.8 8.2 - GP 6/2/2020 1031 0.7 27.6 18,900 11.2 5 7.8 0.65 1032 5.5 27.6 19,000 11.2 6 7.9 - 1033 11.1 27.3 20,900 12.5 2.9 7.6 - LB 6/2/2020 1301 1.1 27.8 3,280 1.7 7.5 8 0.55 1302 6.8 27.8 3,260 1.7 7.5 8 - 1303 11.9 27.8 3,260 1.7 7.5 8.1 - PP 6/2/2020 1245 0.9 27.8 6,520 3.5 7.3 8 0.4 1246 6.2 27.8 6,520 3.5 7.2 7.9 - 1247 12.6 27.8 6,550 3.5 7.2 7.9 - TM 6/2/2020 1230 1 27.9 9,030 5.0 7.1 7.8 0.55 1231 4.7 27.8 9,110 5.1 6.8 7.8 - 1232 7.1 27.7 9,410 5.3 5.4 7.9 - Table 2.6 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of June 22–26, 2020, week 8 after spillway was closed
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 6/23/2020 1001 1.79 28.2 597 0.3 7.1 7 0.75 1002 8.43 28.2 597 0.3 7.1 6.9 - 1003 14.4 28.2 597 0.3 7.1 6.8 - C2 6/23/2020 1101 2.28 28 710 0.3 7.2 7.2 0.9 1102 8.66 28 710 0.3 7.1 7.1 - 1103 15.2 28 710 0.3 7 7 - C4 6/23/2020 1130 1.27 27.9 613 0.3 7.3 7.2 1.1 1131 8.64 27.9 613 0.3 7.2 7.2 - 1132 16.5 27.9 613 0.3 7.1 7.1 - C7 6/23/2020 1201 1.18 27.7 643 0.3 7.2 7.4 1 1202 8.67 27.7 643 0.3 7.2 7.3 - 1203 15.2 27.7 643 0.3 7.1 7.2 - H11 6/23/2020 1301 1.49 27.8 1,410 0.7 6.7 7.1 0.55 1302 7.88 27.7 1,400 0.7 6.5 7 - 1303 13.6 27.7 1,400 0.7 6.5 6.9 - Table 2.7 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of July 20–24, 2020, week 12 after spillway was closed
Station Abbreviation Date Time (CST) Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) SJ 7/21/2020 1401 0.6 29.9 32,100 19.9 6.6 7.9 0.5 1402 3 29.8 32,100 19.9 6.6 7.9 - 1403 9.8 29.8 32,100 19.9 6.4 7.9 - MB2 7/20/2020 1100 0.4 30.6 34,400 21.4 7.1 6.8 0.8 1101 4.5 30.6 34,400 21.4 7.1 6.8 - 1102 9.1 30.6 34,400 21.4 7 6.8 - MB1 7/20/2020 1115 0.5 30.4 35,900 22.5 7.2 6.3 0.9 1116 6 30.3 36,000 22.6 7.1 6.3 - 1117 12.9 30.3 36,100 22.6 7 6.2 - MB 7/20/2020 1131 1 30 40,400 25.7 7 6.3 0.8 1132 9 29.9 40,400 25.7 6.9 6.3 - 1133 15.3 29.9 40,400 25.7 6.9 6.3 - GP2 7/21/2020 1015 1.3 29.6 37,300 23.5 6.5 8.1 0.9 1016 6.2 29.5 38,000 24.0 6 8.1 - 1017 11.4 29.5 38,500 24.4 5.8 8.1 - GP1 7/21/2020 1000 0.8 29.6 39,800 25.3 5.4 8.1 0.65 1001 7.1 29.6 39,800 25.3 5.4 8.1 - 1002 14.1 29.6 39,800 25.3 5.3 8.1 - GP 7/21/2020 1031 0.8 29.4 36,200 22.8 5.8 7.9 0.45 1032 5.2 29.3 36,200 22.8 5.7 7.9 - 1033 10.6 29.3 36,200 22.8 5.6 7.9 - LB 7/21/2020 1301 1.1 29.7 15,600 9.0 7.3 7.9 0.5 1302 5.4 29.7 15,600 9.0 7.3 7.9 - 1303 11.1 29.7 15,600 9.0 7.2 7.9 - PP 7/21/2020 1200 1.2 29.2 22,600 13.6 6.6 7.8 0.45 1201 7.2 29.2 22,700 13.6 6.5 7.8 - 1202 13.4 29.2 22,900 13.7 5.9 7.7 - TM 7/21/2020 1130 0.8 29.8 18,500 10.9 7.8 8 0.35 1131 3.2 29.7 19,000 11.2 7.4 8 - 1132 5.4 29.2 23,700 14.3 4.4 7.6 - Table 2.8 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of July 27–31, 2020, week 13 after spillway was closed
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 7/27/2020 1001 1.5 27.7 361 0.2 7.7 8.1 1 1002 8.75 27.7 361 0.2 7.6 8.1 - 1003 16 27.7 361 0.2 7.6 8.2 - C2 7/27/2020 1101 1.4 27.7 1,770 0.9 7.3 7.7 1.1 1102 8.8 27.7 1,930 1.0 7.1 7.7 - 1103 16.4 28 4,360 2.3 6 7.5 - C4 7/27/2020 1115 1.65 27.6 3,430 1.8 7.4 7.8 1.1 1116 7 27.6 3,440 1.8 7.3 7.8 - 1117 17.6 28.1 4,610 2.5 4.9 7.3 - C7 7/27/2020 1201 1.57 27.7 559 0.3 7.2 7.8 1.1 1202 8.76 27.7 559 0.3 7.2 7.8 - 1203 16.6 27.7 558 0.3 7.4 7.9 - H11 7/27/2020 1301 0.7 27.1 6,520 3.6 7.2 7.7 1 1302 8.5 27.1 6,520 3.6 7.2 7.7 - 1303 15.6 27.1 6,530 3.6 7.2 7.7 - Table 2.9 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of August 31 – September 4, 2020, week 18 after spillway was closed
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 9/1/2020 1001 1.8 29.1 2,350 1.2 7 7.3 1.2 1002 8 29.1 2,380 1.2 6.9 7.2 - 1003 14.9 28.6 7,420 4.1 6.5 1.3 - C2 9/1/2020 1101 1.1 28.8 2,160 1.1 7.6 7.5 0.75 1102 7.9 28.8 2,250 1.1 7.5 7.4 - 1103 15.6 28.4 10,700 6.0 2.7 6.9 - C4 9/1/2020 1130 1.2 28.9 4,080 2.2 7.9 7.9 1.4 1131 8.1 28.9 4,090 2.2 7.8 7.7 - 1132 15.9 28.1 18,800 11.1 1.4 6.9 - C7 9/1/2020 1201 1.6 28.7 6,410 3.5 7.6 7.8 1.1 1202 9.1 28.6 6,430 3.5 7.4 7.5 - 1203 15.1 28.5 11,900 6.8 1 6.9 - H11 9/1/2020 1301 1.3 29 4,520 2.4 7.4 7.7 1 1302 7.7 29 4,530 2.4 7.4 7.7 - 1303 14.4 29 4,550 2.4 7.3 7.7 - Table 2.10 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of September 14–18, 2020, week 20 after spillway was closed
Station Abbreviation Date Time (CST) Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) SJ 9/17/2020 1401 0.17 27 25,300 15.4 6.8 7.5 0.7 1402 1.53 26.3 25,200 15.3 6.7 7.5 - 1403 3.06 26.3 25,300 15.4 6.6 7.5 - MB2 9/17/2020 1000 0.32 25.6 27,800 17.1 6.4 7.7 0.7 1001 1.3 25.5 27,800 17.1 6.4 7.6 - 1002 2.63 25.6 28,500 17.5 6.1 7.5 - MB1 9/17/2020 1015 0.29 25.5 29,000 17.9 6.8 7.8 1 1016 1.55 25.5 29,000 17.9 6.7 7.8 - 1017 3.41 25.5 29,600 18.3 6.5 7.7 - MB 9/17/2020 1031 0.51 25.7 32,000 19.9 6.6 7.8 0.8 1032 2.54 25.7 32,100 20.0 6.4 7.8 - 1033 5.07 25.9 34,300 21.5 5.6 7.8 - GP2 9/17/2020 1045 1.3 25.8 33,200 20.8 6.9 7.9 0.7 1046 6.5 25.8 33,300 20.8 6.8 7.9 - 1047 10.6 25.7 35,300 22.2 6.1 7.8 - GP1 9/17/2020 1100 1.7 25.9 34,800 21.8 6.9 7.9 0.7 1101 6.5 25.7 35,300 22.2 6.6 7.8 - 1102 13.3 25.6 36,100 22.7 6.4 7.8 - GP 9/17/2020 1115 0.6 25.4 36,600 23.1 6.6 7.8 0.3 1116 4.3 25.4 36,700 23.2 6.6 7.8 - 1117 8.8 25.3 37,100 23.5 6.6 7.8 - LB 9/17/2020 1301 0.2 26.6 15,600 9.1 8.9 7.9 1 1302 4.9 26 16,800 9.8 9 8 - 1303 9.5 25.7 18,700 11.0 7.7 7.9 - PP 9/17/2020 1230 1.6 26.3 22,700 13.7 8.5 7.9 0.5 1231 5.2 26.1 22,900 13.8 8.3 7.9 - 1232 10.4 25.7 23,300 14.1 7.4 7.8 - TM 9/17/2020 1130 1.3 25.9 30,700 19.1 6.7 7.7 0.3 1131 3.9 25.7 30,700 19.1 6.6 7.7 - 1132 6.2 25.6 30,700 19.1 6.6 7.7 - Table 2.11 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of September 28 – October 2, 2020, week 22 after spillway was closed
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 9/28/2020 0801 1.13 24.7 5,260 2.8 8.9 7.3 0.9 0802 7.51 24.6 5,290 2.9 8.7 7 - 0803 15.9 23.8 5,880 3.2 5.7 6.7 - C2 9/28/2020 0901 0.9 24.5 5,710 3.1 9.1 7.7 1.1 0902 8.1 24.4 5,710 3.1 8.8 7.5 - 0903 16.1 23.8 6,000 3.3 6.6 7.3 - C4 9/28/2020 0930 0.4 25.3 6,190 3.4 9.5 8.2 1 0931 8.4 24.9 6,490 3.5 8.7 7.7 - 0932 17 23.7 9,400 5.3 4.4 7.3 - C7 9/28/2020 1001 0.6 26 9,240 5.2 10.2 8.4 1.5 1002 8.4 25.3 9,290 5.2 9.7 8.2 - 1003 16 23.8 11,100 6.3 3.8 7.4 - H11 9/28/2020 1131 0.8 25.4 7,830 4.3 8.7 7.9 1.3 1132 8.4 25.2 7,830 4.3 8.6 7.9 - 1133 17.1 25.2 7,830 4.3 8.5 7.9 - Table 2.12 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of October 26-30, 2020, week 26 after spillway was closed
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 10/26/2020 0801 1.7 23.3 6,000 3.3 8.1 7 0.9 0802 9.9 23.3 6,000 3.3 8.1 7 - 0803 14.8 23.3 6,000 3.3 8 6.8 - C2 10/26/2020 0901 1.6 23.3 4,180 2.3 8 7 1 0902 9 23.3 6,780 3.7 7.9 6.9 - 0903 17.7 23.3 6,780 3.7 7.9 6.9 - C4 10/26/2020 0930 2.2 23.5 7,720 4.3 7.1 8 0.7 0931 8.9 23.5 7,720 4.3 7 8 - 0932 17.2 23.5 7,730 4.3 6.9 7.9 - C7 10/26/2020 1001 2 23.6 8,570 4.8 7.9 7.1 0.75 1002 8.9 23.6 8,570 4.8 7.9 7 - 1003 17.4 23.6 8,570 4.8 7.8 6.8 - H11 10/26/2020 1131 1.7 22.8 8,350 4.7 7.8 7 0.85 1132 6.7 22.8 8,450 4.7 7.8 6.9 - 1133 1.6 22.8 8,540 4.8 7.9 6.7 - Table 2.13 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of November 2-6, 2020, week 27 after spillway was closed
Station Abbreviation Date Time (CST) Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) SJ 11/10/2020 1401 1.8 21.3 28,100 17.3 8.3 8 1 1402 5.3 20.6 29,400 18.2 8.1 7.9 - 1403 10 20.7 29,600 18.3 8.4 7.9 - MB2 11/10/2020 1201 2.1 20.9 37,200 23.6 7.6 7.7 1 1202 5.1 20.9 37,200 23.6 7.5 7.7 - 1203 10.9 20.8 37,200 23.6 7.4 7.5 - MB1 11/10/2020 1146 1.9 20.7 36,400 23.0 7.8 7.9 1.4 1147 5.9 20.7 36,500 23.1 7.7 7.9 - 1148 13.4 20.6 37,200 23.6 7.5 7.9 - MB 11/10/2020 1131 1.9 20.8 36,300 23.0 7.9 8 1.5 1132 8 20.4 37,000 23.5 7.2 7.9 - 1133 16.4 20.5 38,400 24.4 7.3 7.9 - GP2 11/10/2020 1101 2.1 20.9 37,800 24.0 8 8 1.3 1102 5.8 20.8 37,800 24.0 7.7 8 - 1103 10.7 20.6 38,400 24.4 7.3 8 - GP1 11/10/2020 1046 1.9 21 40,800 26.2 8 8 1.5 1047 7.5 20.8 40,900 26.2 7.8 8 - 1048 13.7 20.7 41,600 26.6 7.7 8 - GP 11/10/2020 1031 1.8 21.6 43,000 27.7 7.9 8.1 0.4 1032 5.5 21.3 43,100 27.8 7.7 8.1 - 1033 10.9 21.2 43,200 27.8 7.6 8.1 - LB 11/10/2020 1301 1.8 21 15,200 8.9 9.7 8.1 0.9 1302 5.3 20.9 15,200 8.9 9.6 8.1 - 1303 10.2 20.6 15,300 8.9 9 8 - PP 11/10/2020 1231 1.7 21.4 23,700 14.4 8.2 8 0.7 1232 6.1 21.1 24,400 14.8 8.1 8 - 1233 12.2 21 24,700 15.1 8.1 8 - TM 11/10/2020 1216 1.5 21.5 32,000 20.0 8.1 8 0.8 1217 4.1 21.5 32,000 20.0 8.1 8 - 1218 7.3 21.5 32,200 20.1 8.1 8 - Table 2.14 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2020.
Field data for week of November 16-20, 2020, week 29 after spillway was closed
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 11/16/2020 1001 2.80 19.7 6,440 3.5 8.8 7.4 1.2 1002 9.20 19.7 6,430 3.5 8.8 7.4 - 1003 17.40 19.7 6,440 3.5 8.8 7.4 - C2 11/16/2020 0901 2.20 19.8 7,730 4.3 8.9 7.5 0.9 0902 9.40 19.8 7,730 4.3 8.9 7.4 - 0903 17.50 19.7 7,730 4.3 8.9 7.4 - C4 11/16/2020 1030 2.20 19.8 7,560 4.2 8.9 7.5 0.65 1031 8.60 19.8 7,560 4.2 8.9 7.4 - 1032 18.60 19.8 7,560 4.2 8.9 7.4 - C7 11/16/2020 1201 2.80 19.8 7,980 4.4 8.9 7.4 0.6 1202 8.20 19.8 7,980 4.4 8.9 7.4 - 1203 18.30 19.8 7,980 4.4 8.7 7.2 - H11 11/16/2020 1101 2.70 19.4 9,150 5.1 8.6 7.4 0.6 1102 7.30 19.5 9,370 5.2 8.5 7.3 - 1103 15.10 19.7 9,700 5.5 8.3 7.2 - Table 2.15 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2021.
Field data for week of Aug 13, 2021 - Aug 20, 2021, no spillway operation in 2021
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 8/13/2021 0900 0.50 30.5 725 0.4 7.6 7 1.5 0901 7.20 30.1 723 0.4 7.7 7.1 - 0902 14.40 30 723 0.4 7.7 7.2 - C2 8/13/2021 1001 0.50 30.2 825 0.4 6.9 7.1 1.2 1002 7.10 30 824 0.4 6.9 7.1 - 1003 14.00 29.9 823 0.4 6.8 7.2 - C4 8/13/2021 N/A - - - - - - - C7 8/13/2021 1201 0.50 30.1 1,560 0.7 7.2 6.8 1.1 1202 7.20 30 1,550 0.7 6.8 6.8 - 1203 15.40 29.9 1,550 0.7 6.9 6.8 - H11 8/12/2021 1101 0.90 30.4 1,370 0.7 7.8 7.2 1.3 1102 6.90 30.2 1,360 0.7 7.2 7.2 - 1103 11.70 30.1 1,360 0.7 6.6 7.2 - Table 2.16 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2021.
Field data for week of Sept 27, 2021 - Oct 1, 2021, no spillway operation in 2021
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 9/27/2021 0730 0.50 24.9 1,950 1.0 7.3 7.4 0.8 0731 7.20 24.9 1,950 1.0 7.3 7.3 - 0732 14.40 24.8 1,950 1.0 7.3 7.3 - C2 9/27/2021 0801 0.50 25.2 3,390 1.8 8.1 7.8 0.6 0802 7.10 25.2 3,390 1.8 8.1 7.7 - 0803 14.00 25.2 3,400 1.8 8.1 7.6 - C4 9/27/2021 0830 0.50 25.4 4,260 2.3 7.9 7.8 0.55 0831 7.50 25.4 4,260 2.3 7.9 7.8 - 0832 14.80 25.4 4,260 2.3 7.9 7.8 - C7 9/27/2021 0901 0.50 24.8 3,370 1.7 7 7.6 0.55 0902 7.20 24.8 3,370 1.7 7.6 7.6 - 0903 15.40 24.8 3,360 1.7 7.6 7.6 - H11 9/24/2021 1101 1.10 25.2 3,320 1.7 7.8 7.5 0.6 1102 5.90 24.9 3,320 1.7 7.7 7.4 - 1103 11.90 24.7 3,310 1.7 7.5 7.2 - MB2 9/27/2021 1051 1.6 26.1 4,150 2.1 8.2 7.9 0.65 1052 5.3 25.3 8,920 4.9 5.1 7.3 - 1053 9.3 25.2 11,300 6.4 4.2 7.3 - MB1 9/27/2021 1041 1.5 25.6 3,960 2.1 8.5 8 0.8 1042 5.4 24.9 4,820 2.6 7.1 7.6 - 1043 12.3 25.1 11,400 6.5 3.9 7.2 - MB 9/27/2021 1031 2.5 25.4 7,870 4.3 8.8 8.3 0.9 1032 7.4 25.1 10,900 6.2 6.3 7.8 - 1033 14.8 25.3 17,300 10.1 4.1 7.4 - GP2 9/27/2021 1151 1.8 25.5 8,450 4.6 8.7 8.3 1 1152 6.8 25.4 9,710 5.4 8 8.2 - 1153 11 25.3 17,600 10.3 6 7.8 - GP1 9/27/201 1141 1.4 25.3 13,600 7.8 8 8.1 1.3 1142 7.6 25.1 14,200 8.2 6.6 8 - 1143 13.8 25.4 23,700 14.2 4.9 7.7 - GP 9/7/2021 1131 2 25.1 10,700 6.0 8.1 8.2 0.8 1132 5.2 25.2 11,700 6.6 7.7 8.1 - 1133 10.5 25.3 12,900 7.4 7.4 8 - Table 2.17 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2021.
Field data for week of Oct 25, 2021 - Oct 29, 2021, no spillway operation in 2021
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 10/26/2021 1115 2.00 24.5 3,390 1.8 8 7.7 0.4 1116 8.00 24.3 3,390 1.8 7.7 7.6 - 1117 16.00 24.2 3,390 1.8 7.7 7.7 - C2 10/26/2021 1101 2.32 24.2 3,250 1.8 7.8 7.7 0.35 1102 8.42 24.1 3,250 1.8 7.7 7.7 - 1103 16.90 24.1 3,250 1.8 7.8 7.8 - C4 10/26/2021 1030 1.98 24.2 3,340 1.8 8.1 7.8 0.3 1031 8.33 24.1 3,340 1.8 8 7.8 - 1032 18.10 24.1 3,340 1.8 7.9 7.8 - C7 10/26/2021 1001 2.28 23.8 2,680 1.5 7.4 7.6 0.2 1002 9.16 23.8 2,680 1.5 7.4 7.7 - 1003 17.50 23.8 2,680 1.5 7.4 7.7 - H11 10/28/2021 0930 2.70 23.1 2,610 1.5 8 7.2 0.1 0931 6.39 23.1 2,610 1.5 8 7.1 - 0932 13.40 23.1 2,610 1.5 8 6.9 - MB2 10/25/2021 1410 1.2 25.1 12,000 6.8 7.3 7.7 1 1411 4.44 24.8 12,500 7.2 7.2 7.7 - 1412 9.38 24.7 13,200 7.6 7.1 7.7 - MB1 10/25/2021 1400 1.52 25.2 10,400 5.8 7.6 7.7 1 1401 5.52 24.2 14,200 8.4 6.7 7.6 - 1402 10.2 24.2 16,000 9.5 6.4 7.6 - MB 10/25/2021 1301 1.95 25.5 14,700 8.4 7.7 7.9 0.9 1302 7.45 24.4 17,800 10.6 7.3 7.9 - 1303 13.4 24.2 18,400 11.1 7.2 7.9 - GP2 10/25/2021 1230 1.55 24.8 19,600 11.7 7.5 8 0.8 1231 5.36 24.8 19,600 11.7 7.5 8 - 1232 11.3 24.7 19,700 11.8 7.4 8 - GP1 10/25/2021 1200 1.59 25.6 16,800 9.7 7.8 8 1.2 1201 7.66 24.4 22,800 13.9 7 7.9 - 1202 13.2 24.4 23,000 14.1 7 7.9 - GP 10/25/2021 1101 1.4 24.9 19,900 11.9 7 7.9 0.55 1102 4.82 24.8 20,000 12 6.9 7.9 -- 1103 10.8 24.8 20,000 12 6.8 7.8 -- Table 2.18 - U.S. Geological Survey field water-quality data from selected sampling stations in Lakes Pontchartrain/Borgne and western Mississippi Sound, 2021.
Field data for week of Dec 6, 2021 - Dec 10, 2021, no spillway operation in 2021
Station Abbreviation Date Time Sample Depth (ft) Water Temperature (°C) Specific Conductance (µS/cm) Salinity (ppt) Dissolved Oxygen (mg/L) pH (units) Secchi Depth (m) C1 12/7/2021 1045 2.53 17.1 2,940 1.6 10.3 7.9 0.9 1046 7.59 17.1 2,940 1.6 10.2 8 - 1047 16.00 17.1 2,940 1.6 10.2 8 - C2 12/7/2021 1031 2.45 17.2 3,010 1.6 10.4 8.1 0.7 1032 7.72 17.2 3,010 1.6 10.4 8.1 - 1033 17.60 17.2 3,010 1.6 10.3 8 - C4 12/7/2021 1020 2.78 16.9 2,760 1.5 9.9 7.9 0.5 1021 8.66 16.9 2,760 1.5 9.9 7.9 - 1022 19.10 16.9 2,760 1.5 9.8 7.9 - C7 12/7/2021 1001 2.62 17 2,020 1.0 9.6 7.9 0.3 1002 8.48 17 2,020 1.0 9.6 7.9 - 1003 17.50 17 2,020 1.0 9.6 8 - H11 12/7/2021 0901 2.76 18 3,250 1.8 9.4 8 0.7 0902 8.74 18.3 4,720 2.5 9.2 8.1 - 0903 17.70 18.4 5,750 3.1 9.1 8.1 - *USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
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