Water Quality in Lake Pontchartrain and western Mississippi Sound during openings of Bonnet Carré Spillway Active
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.
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.