Weirs Closed

[MathGeek]

Originally Posted by noodle creek

My question is, if we rocked the ship channel leaving a little cut where super cut used to be and a little cut at the washout, would the weirs still be just as necessary?

Good question. The answer is a definitive yes. To keep Big Lake as a brackish estuary with suitable salinities for good growth of oysters and reproduction of trout, etc. it needs to be saltier at times than you would want to have directly connected to the marsh between 5 and 15 ppt, depending on the time of year and water temps, etc.

It may also happen that the separation between the channel and lake is not always sufficient to keep salinities in the lake sufficiently low. An event like an extended period with low rain will eventually cause the salinity in the lake to approach 20-30 ppt. If there is no fresh water flowing into the system, the salinity will creep higher and higher. Reducing the coupling of the system to the Gulf just slows the process down and lowers the average salinity over time, it does not mean a high salinity event can never occur in the lake.

But keeping the salinity in the lake at 5-15 ppt most of the time would mean that the weirs could be open many more days per year than they are now - maybe an average of 240+ days per year: possibly 300 days in a good year and only 150 days in a bad year.