Vermilion Water Watch: Improving Salinity with Heavy-Rain Risk

Updated: Friday, September 11, 2026, at 3:50 a.m. CDT

Publishing status: Review needed. Essential observations are current and no marine advisory is active. Human review is required because NWS expects scattered to numerous storms, possibly beginning relatively early, with very heavy rain and localized flooding where storms linger. The newest NASA image is also heavily cloud obscured and cannot provide a reliable view of coastal water color.

Fishing-impact summary

The Atchafalaya River pulse continues to recede. Simmesport discharge declined from 118,000 ft³/s Thursday morning to 110,000 ft³/s. This gradual upstream decline should reduce freshwater pressure on nearby coastal waters if weekend rainfall does not produce another rise.

Cypremort Point salinity measured 17 ppt at 3:00 a.m. and ranged from 14 to 17 ppt during the preceding day. That is a narrower and saltier range than Thursday's 12–17 ppt, indicating improved local stability without proving uniform salinity throughout Vermilion Bay.

Morgan City turbidity eased from 27.5 to 25.6 FNU and ranged from 17.3 to 33.6 FNU during the past day. Clarity may be gradually improving at the lower-river station, but fresh runoff from today's storms could interrupt that trend locally.

The early tide is rising toward a 7:22 a.m. high. A moderate late-morning fall and similar afternoon rise should provide distinct but temporary current windows. Southwest Pass, outer Marsh Island and deeper reefs remain the stronger starting points for Specks, while protected Marsh Island drains and oyster edges remain practical for Redfish, Black Drum and Flounder.

What changed since the prior report

Simmesport discharge declined from 118,000 to 110,000 ft³/s, continuing the recession of the natural Atchafalaya pulse.
Wax Lake Outlet increased from 48,800 to 55,300 ft³/s at the early-morning observation. Its daily range was 39,200–70,700 ft³/s because tide and backwater influence the station.
Morgan City discharge changed from 63,900 to 59,400 ft³/s. Its preceding-day range was 20,500–92,300 ft³/s, so short-term changes remain primarily useful as local outlet observations rather than direct measures of the upstream trend.
Morgan City turbidity improved from 27.5 to 25.6 FNU and ranged from 17.3 to 33.6 FNU.
Morgan City dissolved oxygen changed from 6.3 to 6.2 mg/L, remaining within its recent range.
Cypremort Point salinity remained 17 ppt, while its daily minimum improved from 12 to 14 ppt.
Cypremort Point wind increased from southeast at 5.2 mph to south-southwest at 9.9 mph.
NWS increased concern for very heavy rain and localized flooding today and Saturday as unusually deep moisture supports scattered to numerous storms.

Measured conditions

Measurements are provisional USGS observations.

Atchafalaya River at Simmesport: 110,000 ft³/s and 7.25-foot gage height at 3:30 a.m. Discharge ranged from 110,000 to 118,000 ft³/s during the preceding day and continues to decline.
Wax Lake Outlet at Calumet: 55,300 ft³/s, 2.28-foot gage height and 1.32-ft/s velocity at 2:45 a.m. Tide and coastal backwater continue to produce substantial short-term variation.
Lower Atchafalaya River at Morgan City: 59,400 ft³/s and 2.25-foot gage height at 3:00 a.m. Water temperature was 30.2°C/86.4°F, salinity 0.2 ppt, turbidity 25.6 FNU and dissolved oxygen 6.2 mg/L at 3:30 a.m.
Vermilion Bay near Cypremort Point: South-southwest wind measured 9.9 mph at 3:00 a.m. Water temperature was 30.3°C/86.5°F, salinity was 17 ppt and gage height was 1.87 feet. Salinity ranged from 14 to 17 ppt during the preceding day.

The USACE New Orleans District September news archive contains no notice of a Morganza Floodway opening or comparable new managed freshwater release affecting the report area. Current upstream conditions remain consistent with a naturally receding river pulse.

Official forecast

The NWS Lake Charles Area Forecast Discussion issued at 12:22 a.m. expects scattered to numerous showers and thunderstorms today. Deep atmospheric moisture is above the 90th percentile, and daytime heating may allow storms to develop relatively early.

NWS says very heavy rain may occur at times, with localized flooding possible where a storm remains over the same area. Similar conditions are forecast Saturday. Storm coverage should begin decreasing Sunday as upper-level ridging gradually returns.

Afternoon temperatures should reach the low to mid-90s, with heat indices of 99–107°F. Patchy light mist is possible around sunrise, although mostly VFR conditions are expected outside showers and storms.

For Vermilion and West Cote Blanche Bays, the official 3:09 a.m. marine forecast calls for:

Friday: West wind around 5 knots, becoming southwest late. Bay water with a light chop. Showers become likely during the afternoon, with thunderstorms possible throughout the day.
Friday night: Southwest wind 5–10 knots and a light chop, with showers and a slight overnight thunderstorm chance.
Saturday: Southwest wind 5–10 knots and a light chop. Showers become likely during the afternoon, with thunderstorms possible.
Sunday: South wind around 5 knots and smooth bay water, with showers likely during the morning and additional storms possible during the afternoon.

No Louisiana, Texas or Gulf marine watch, warning or advisory was listed. Winds and waves can become substantially higher in and near thunderstorms.

Tides and storm-driven movement

NOAA astronomical predictions for Cypremort Point, relative to MLLW, are:

Friday low: 12:44 a.m. at 0.62 feet
Friday high: 7:22 a.m. at 1.59 feet
Friday low: 12:54 p.m. at 0.97 feet
Friday high: 6:51 p.m. at 1.60 feet
Saturday low: 1:20 a.m. at 0.86 feet
Saturday high: 7:09 a.m. at 1.52 feet
Saturday low: 1:26 p.m. at 0.72 feet

Water is rising before daylight toward the 7:22 a.m. high. The late-morning fall is approximately 0.62 feet, followed by a similar 0.63-foot rise through the afternoon. A 0.75-foot fall follows the evening high.

The USGS Cypremort Point gage uses a different datum from NOAA MLLW and cannot be compared directly with these predicted heights. Heavy rain and thunderstorm outflow may temporarily accelerate, weaken or reverse current through shallow drains, Marsh Island cuts and Southwest Pass.

Likely water movement — fishing inference

This section is a fishing inference based on measured conditions, astronomical tides and official wind forecasts rather than direct bay-wide current observations.

The early incoming tide should move water through Southwest Pass and other bay connections toward Marsh Island and the interior bay until approximately 7:22 a.m. The observed south-southwest wind may provide a modest northward or northeastward surface influence, but the official forecast calls for generally light west-to-southwest wind.

A moderate outgoing phase should develop after the morning high and continue toward the 12:54 p.m. low. Protected drains and constricted cuts may provide usable movement for Redfish, Black Drum and Flounder, although thunderstorm runoff or outflow could disrupt the expected pattern.

The afternoon rising tide may carry relatively cleaner water toward Southwest Pass and outer Marsh Island. Fresher or more discolored water remains more likely around eastern Marsh Island, rain-fed drains and Atchafalaya-facing waters. This distribution is not measured directly and must be verified locally.

Water clarity and salinity outlook

Morgan City turbidity improved slightly to 25.6 FNU from 27.5 FNU Thursday morning. Its 17.3–33.6 FNU daily range indicates continued but less extreme variability at the lower-river outlet.

Cypremort Point does not have a turbidity sensor. Its 14–17-ppt daily salinity range is more stable than the 12–17-ppt range in Thursday's report and substantially improved from Tuesday's 10-ppt minimum.

Expect the better prospects for clear, salty water around Southwest Pass, the outer or southern side of Marsh Island and deeper reef edges. Eastern Marsh Island, protected canals and drains may remain more variable. Very heavy rain today or Saturday could quickly reduce clarity and salinity inside individual drainage basins.

NASA Worldview

September 11 VIIRS/SNPP corrected-reflectance true-color imagery was unavailable at the early-morning update. The newest available scene was acquired September 10, 2026.

NASA Worldview regional view for September 10, 2026

Clouds cover most of Vermilion Bay, Marsh Island and the adjoining Gulf in the September 10 image. A satellite swath boundary also crosses the regional view. No reliable plume boundary or water-clarity conclusion was derived from the imagery.

Satellite imagery is contextual only. It does not prove salinity, dissolved oxygen, harmful algae, general water quality or fish movement. Clouds, sediment, haze, sun glint and shallow-bottom reflectance can all change apparent water color.

Best areas

Specks: Southwest Pass, outer or southern Marsh Island and deeper reef edges after clarity, salinity and bait are verified.
Redfish and Black Drum: Protected Marsh Island drains, points and oyster edges during the late-morning falling tide.
Flounder: Cuts where draining marsh water meets clearer bay water, provided current and storm conditions remain manageable.
Tripletail and Cobia: Nearshore structure or floating cover only during a confirmed storm-free period with adequate visibility and a short return route.

Species-specific implications

Redfish: The 14–17-ppt Cypremort range remains suitable for Redfish. Focus on drains and oyster edges carrying bait during the late-morning fall.
Specks: Improving salinity stability is favorable, but clarity and bait remain the deciding factors. Favor Southwest Pass, outer Marsh Island and deeper reef edges over heavily stained drainage water.
Tripletail: Light background wind may support sight fishing between storms. Thick clouds, rain and poor visibility may substantially reduce effectiveness and safety.
Cobia: No direct biological change is confirmed. Numerous storms, heavy rain and reduced nearshore visibility are the main trip-planning limitations.
Black Drum: Drum should tolerate the remaining freshwater influence. Oyster edges and dirty-to-clean boundaries may concentrate food during falling water.
Flounder: The approximately 0.62-foot late-morning fall may improve ambush opportunities at cuts and pass edges. Avoid constrictions affected by storm outflow, debris or excessive current.

Recommended approach

Use the early incoming tide to check Southwest Pass, outer Marsh Island and deeper reef edges for Specks. Confirm water color and bait before committing because the satellite image does not provide usable clarity guidance.

After the 7:22 a.m. high, shift toward protected Marsh Island drains, points and oyster edges where the falling tide produces visible current. Target Redfish, Black Drum and Flounder around manageable flow rather than the strongest constriction.

Keep radar and the current marine forecast available throughout the trip. Because storms may develop relatively early, maintain a short route to protected water and do not make an exposed run based solely on the light background-wind forecast.

Expected timing and duration

Incoming movement should continue through the 7:22 a.m. high. The primary daytime outgoing window extends from the morning high toward the 12:54 p.m. low. Water rises again through the afternoon toward the 6:51 p.m. high.

The Atchafalaya pulse should continue receding if the Simmesport trend persists. Cypremort Point salinity has become more stable, but heavy rain today and Saturday may renew localized freshwater and stained-water conditions. Protected canals could respond within hours, while broader bay effects would depend on rainfall placement and duration.

Confidence, uncertainty and localized conditions

Confidence is high in the current USGS observations, NOAA tide predictions and official light-wind forecast. Confidence is moderate in the expected incoming and late-morning outgoing sequence. Confidence is lower regarding rainfall placement, storm timing and the exact location of cleaner water.

Cypremort Point and Morgan City are individual monitoring stations. Cypremort Point does not define salinity or clarity across the entire bay, and Morgan City does not establish conditions around Southwest Pass. Eastern Marsh Island may remain substantially fresher or more stained than outer Marsh Island, especially after localized downpours.

Harmful algae and dissolved oxygen

LDEQ's August 20, 2026 notice concerning visible blue-green algae around Henderson Lake and other Louisiana waterways remains the latest listed state HAB notice. No new notice was identified specifically for Vermilion Bay, Cypremort Point, Marsh Island or Southwest Pass.

Morgan City dissolved oxygen measured 6.2 mg/L and ranged from 6.0 to 6.3 mg/L during the preceding day. This is not an oxygen-collapse signal at that station, but it does not establish conditions inside shallow, warm or stagnant canals. Avoid visible green scum, paint-like streaks, distressed bait or fish kills, and do not harvest from visibly affected water.

Safety notes

Human review is required because NWS expects scattered to numerous storms capable of very heavy rain and localized flooding. Storms may develop relatively early and can produce dangerous lightning, reduced visibility and abrupt increases in wind and waves.

The newest NASA imagery is heavily cloud obscured and provides no reliable check on bay-wide water color. No marine advisory is active, but heat indices may reach 99–107°F. Carry adequate water, provide shade when possible, maintain reliable communications and avoid exposed Marsh Island or Southwest Pass crossings whenever storms approach.

Vermilion Bay grows memories with shoulders.