March 8, 2013
Summary of accomplishments:
- Most of Cell 3 is at -1” ML or better
- Spartina patens and Scirpus olneyi are spreading well
Impediments: low water in the pond and canal
This report can be downloaded in PDF file format by clicking the Dredge and Rainey Report, Low Low Water hyperlink.
It has been another month without appropriate conditions for dredging. Winter fronts have kept water levels low in the canal and/or the pond, or it rained for weeks at a time, preventing us from finishing Cell 3. This week, the water was so low for so long that there were mud cracks forming in some places in Cell 2, the substrate of Cell 1 was exposed, and we could see the hole where the water is leaking through our outer containment into the outer pond.
Tuesday, Timmy and I joined a group to see another small dredge operation near Golden Meadow (see March 5, 2013 report), Wednesday we worked on the pump shed, Thursday we burned marsh at the site of our next dredge project so we can survey for the permit.
Wednesday, March 6
Sunrise revealed extremely low water, exposing the mud bottom of our backyard pond (a part of Belle Isle Lake), and the boats in the boatshed sitting on bottom. It was obvious that we could do no dredging again today.
Instead, we spent most of the day constructing the landing and stairs to the new pump shed. It looks to be on the same level as the house. Once the pump is moved and installed in the insulated shed, it should be protected against freezes and most storm surges. We finished that task around 2:00.
By the time we had finished, the water had come up a bit, so we decided to cruise down to the proposed dredge site to burn the marsh there. The area had not been burned in a while, and it would make the pre-project surveying that was necessary for the coastal use permit much easier.
We slid the Goose off the mud in the boatshed into the canal and headed south. I’d never seen the water so low. At roughly two feet below normal, the canal banks were exposed well out into the water, showing the relief and obstacles I didn’t know were there. We noticed schools of small mullet in front of a weir, so took the opportunity to catch bait for our supper. The wind and incoming current were relentless. While Timmy threw the castnet, I tried to keep the Goose from running aground.
When we arrived at the intersection of the canal leading to the new dredge site, we were surprised to see the bottom exposed for most of the crossing. The abundance of fill material for our new project was obvious and welcome, but it was a problem for today. There was no way to access the area with the Goose. So, it was back to headquarters, and shopping in the various waterways for supper.
Thursday, March 7
Dawn showed the water level had increased overnight, filling the backyard pond and floating the boats back up to the dock. The early morning quiet was interspersed with the distant sound of snow geese as they made their way north.
Even though the water level was normal now, it would take several days, even if the water level remained up, for the water to make it into the interior ponds. The good thing to see with so much water moving in, was that it was fresh and muddy – both good for the marsh.
Dredging was out again for today. We headed south to the new dredge site.
Starting at the northwest side of our study area, we would tie up the boat, find our way through the deer and hog trails to the marsh, and Timmy would use a torch to light the dead marsh grass in a few strategic places. We would watch to make sure it caught and that it was going the direction we expected, then beat a retreat to safety. This was repeated at several landings along the canals bordering our new study area.
There’s a lot of controversy surrounding marsh burning, but the argument seems to be mostly between people who have never seen the results or compared the health of a marsh burned or not burned. We burn in the winter months on a rotating basis, on areas with a thick overburden of dead material, usually every 2-3 years. We pick the time and conditions, with appropriate soil moisture and wind direction. Pockets of marsh around a waterway or isolated by wind/fire deviations provide sporadic cover for wildlife. Within a month, there is a thick, solid, green marsh in place of a brown one with shoots struggling to reach the light.
Many animals take advantage of the winter burns, including snow geese that prefer the open areas to feed. At the first smoke plume, raptors and other birds come from miles around to feed on the insects and smaller creatures fleeing the flames. I’ve watched grackles actually sit in the smoke waiting for supper to pop up. The fires don’t burn active muskrat mounds, and the new shoots feed another generation. Sparrows seem to love the open areas around isolated marsh and bush pockets. Red-tailed Hawks were seen sitting on muskrat houses where they could look over the expanse of recently burned fields.
Last summer, there were 14 marsh fires caused by lightening on our neighbor’s property where they had not burned, all during the critical bird breeding season. Only one fire made it to our property.
Blue-winged Teal flushed from one of the ponds in our target area, and we could hear Clapper Rails and Common Gallinules in the nearby marsh. Cruising the canals on our way back showed that Little Blue Herons and Yellow-crowned Night-herons were back from their winter vacations. An Osprey flashed across the canal in front of us. I could hear Common Yellowthroats in the trees along the way.
After a late lunch, we took a ride down to the dredge marsh creation site. I wanted to make sure I wasn’t missing out on a dredging opportunity. As we walked out onto the boardwalk, it was immediately obvious that I had no reason to feel any guilt about not dredging. In the outer pond to our right, short-legged shorebirds were wading around in ankle deep water, and our outer containment was visible to the mud. The water level in the pond wasn’t measurable, but it had to be 12 inches below marsh level.
This meant that our study cells were completely drained. The fact that mud cracks were throughout cell 3 and into Cell 2 were evidence that the water level has been low so consistently that it hasn’t made it into the pond for any significant wetting event. Cell 4 was completely covered with dried and curled algal mat material, making it look crunchy. The unvegetated mud in Cell 5 had a different texture, like it had been extruded from a grinder or pierced repeatedly to look crumbly.
However, the regular rain events have been flushing the marsh grass and mud consistently enough to promote rapid marsh growth, especially at this time of marshhay cordgrass (Spartina patens). I’m not sure I knew that patens would spread so rapidly and thickly by rhizome, but it was obvious since all of the growth was adjacent to older marsh establishments. Cells 4 & 5 are marked by growth of 3-square (Scirpus olneyi), but Cell 3 is being dominated by Spartina patens. I will be curious to see the results of LSU’s vegetative study.
Karen A Westphal and Timmy J Vincent, National Audubon Society Louisiana Coastal Initiative and the Paul J Rainey Wildlife Refuge 6160 Perkins Road, Suite 215, Baton Rouge, LA 70808 225-768-0921x202 office, firstname.lastname@example.org