re: Planned freshwater diversions will doom LA salt fishing

I talked to a buddy of mine that is a retired environmental (coastal) engineer. He retired from the state a couple of years ago. He said a few things but here are three.

1. naturally you will have freshwater marsh, intermediate marsh and at the fringe saltwater marsh. Saltwater marsh should be at the margin of the gulf.
2. anybody against river diversion projects have an ulterior motive, ie oyster fisherman will have to harvest farther south, crabbers will have to go farther south, etc.
3. the major problem is subsidence. that the flooding that had always churned and deposited silt is gone and now marsh is compacting.

and as a bonus: the Mississippi is levied way past what it needs for flood control. Captain Eades devised the plan to have a narrow channel to jettison the silt out of river bed.....and it worked! but most of the silt falls off the continental shelf now.

I agree with that to a point. Marshes and islands protect the interior marshes and swamps behind them from too much damage. Start building marshes, and stop jamming up estuaries and let them take sediment into the lakes naturally. That will negate the subsidence


I haven't read the coastal plan in a while, but IIRC, it didn't address the interior marsh building by estuaries carrying sediment

People are misinformed

The master plan diversions are all going to be designed to maximize sediment capture.

Which is why it is called the master plan and not the Alabama plan

Main pass is a distributary in the cubits gap sub delta. It is in the detoriation phase of the sub delta progression. Google sub delta life span.

They build for a century or so and then degrade. It is cyclical. In the early 1800's, that was all open water, till a fisherman named cubit cut a hole in the natural levee...

Looking at google earth images from 1998 is not going to do you any good in coming up with arguements/observations

I'm in car line picking up the minnows from school, y'all lemme know if i'm banned from rnr now lol

I have a friend who worked over five years on this project, along with many others, for LA Coastal Restoration.

He would disagree with your doomsday theory. I've asked him. Even the short term impact is negligible when compared to other options.

The plan is public record. I need to go through it all to formulate my own opinion.

Anyway, just letting you know that the men and women who researched and designed the plan didn't just throw it together overnight.

Most of those men and women are Sportsman, like yourself.

quote:

---

Concerning storm surge damage; what is the difference between land above the water surface surrounded by deeper bays, and submerged shoals surrounded by shallower bays? Looks to me like there is a certain quantity of dirt above and below the water surface in the LA marsh and its being redistributed, but its not going anywhere beyond the territorial borders. With storm surges in excess of 10 ft, I don't see the benefit of one over the other.

---

A valid point...and there really isn't much agreement out there concerning how much a wetland actually reduces storm surge. Ridges and barrier islands play a bigger role IMO.

Also, no matter how much land we create with diversions, dredging, etc, it still won't reduce the need to continually improve structural flood protection. The land that we've built on is still sinking. Storm surge will only get worse if we're speaking in relative terms, because our infrastructure will continue to sink. No number of diversions will solve that.

A marsh can hold a lot more water than an open lake.

Intuitively, you would think so. But results are pretty mixed when people have tried to actually quantify it.