Dredge and Rainey Report Low Water

Dredge and Rainey Report
Low Water

November 09, 2012

 

Summary of accomplishments:

  • No dredging this week
  • Total time pumped directly into Cell 3 (.366 acres) = 42.75 hours
  • Total time in study cells = 189 hours

Impediments: Low low water

Wednesday, November 7

Karen arrived at the landing at 8:00 with a temp of 45°. Timmy was in town taking care of errands and picking up supplies. I loaded up, launched the Avocet, bundled up, and headed to the Refuge. It was a beautiful morning, with a light north breeze, clear sky, and flat bay.

On my way into the refuge, I stopped by the dredge site to assess water level in the pond.  As I walked out onto the boardwalk, I could hear geese honking. Finally I thought to look up and saw several Vs passing the quarter moon. The first few groups were white-fronted geese with a few snow geese, and the last groups were almost all snow and blue geese.

Back on Earth, 4 Black-necked Stilts were wading around in water about 3 inches deep next to the outer containment of Cell 1, and a few tiny peeps that had to be Least Sandpipers left the mudflat in a hurry. The water level was again at -7” ML.

Figure 1. Geese flew overhead as I walked out to visit the dredge pond - white-fronted geese on the left and snow geese on the right.

Figure 1. Geese flew overhead as I walked out to visit the dredge pond - white-fronted geese on the left and snow geese on the right.

I discovered that LSU had constructed walkways in Cell 5 over the weekend. This is a mixed blessing – it is nice to be able to walk across the cell, but the walkways are not aesthetically pleasing for my photography and progress comparisons. I was very glad I took plenty of photographs last week. The walkways will provide new platforms for bird and wildlife observations.

I continued on to the headquarters to wait for Timmy to return. Since I couldn’t dredge with extreme low water in the canal, I was available for Sanctuary tasks. I let the puppy out of her kennel and took her birding with me down the sanctuary trail for a while. Timmy still wasn’t back so I set up my office in the house and worked on my laptop. We have internet, cell phone service and Wifi even at the remote location of the headquarters, so I can do my reports and computer work just as easily here as in the office in Baton Rouge. This makes waiting for appropriate dredging conditions convenient.

When Timmy returned, we headed out to the backyard for a few hours to cut reeds and bushes that block the view of the backyard pond. Then we took a run to the weir through extremely shallow water for bait and went fishing for supper.

Thursday, November 8

Sun-up was at 6:30. The wind had shifted overnight, and the water had moved back into the canals and waterways. There is a delay before the water level in the interior marshes is affected, but we were optimistic anyway. The water was a cool 65° with a salinity of 5.4 ppt.

Figure 2. Cool dawn with the sun to the south end of the backyard pond.

Figure 2. Cool dawn with the sun to the south end of the backyard pond.

The plan today was for Timmy to bring the airboat to the dredge area so we could move the dredge outfall away from the containment. However, he had some other duties to attend to first. I headed over to the dredge site around 8:00 am, leaving Timmy at work clearing the area across from the headquarters.

Figure 3. Grounds maintenance across from the headquarters.

Figure 3. Grounds maintenance across from the headquarters.

I pulled up to the dredge area and tied off the boat, hoping that the higher tide had made it into the interior marshes. It hadn’t. The pond was still at -7” ML. The walk out on the boardwalk held another surprise as I found the super shallow water and mudflat had attracted a multitude of hungry birds. On either side of the outer containment of Cell 1, Black-necked Stilts, Willets, Greater Yellowlegs, Dowitchers and Least Sandpipers were working the mud. Beyond them were a flock of Green-winged Teal and a Roseate Spoonbill in the shallow water. In the background in a little deeper water, I could see just a portion of a massive flock of Gadwall/grey ducks behind the marsh islands. The birds were so energetic and talkative in their feeding frenzy that I flipped my camera to video and took a few minutes propped up on one of the boardwalk posts (http://youtu.be/NreTcGnFb70).

My purpose here today was to try to dredge for at least an hour. Even though the water level was low in the pond, it was high enough in the canal to dredge. Normally, we avoid dredging when the water is low. A big difference in water level across containment can cause a head pressure where the weight of the water forces an escape route through the soft substrate under the containment wall. We were hoping that a couple of hours of dredge effluent would spread a layer of mud through the cell without filling it too high to cause this. And, we needed to move the outfall end of the hose away from the containment so that the force of the effluent wasn’t pounding directly on the containment.

Even though I knew Timmy was bringing the airboat, I couldn’t resist trying to move the hose by myself. I untied the end of the hose from the dock and walked the rope through the marsh around the north edge of the pond, and pulled. The end of the hose pulled easily, but it folded into a kink that wouldn’t flip or pull through. Rather than struggling with it, I left the rope there for the airboat and went back to the walkways for more pictures and observations.

I walked the boardwalk and new walkways over to Cell 5. With the sun coming through the grass in the center of Cell 5 that was now only a few feet distant, I discovered that it was a different Scirpus (Schoenoplectus) than that spreading from the perimeter. It appeared to be S. robustus, or saltmarsh bulrush. I went back to Cell 4 and confirmed that this was also the grass that was colonizing the new mud away from the edge there as well.

So, my plant list for the dredge area is increasing as I pay attention instead of assuming I know what’s there. Eleocharis parvula (spike-rush) is the first to colonize the wet mud, and is currently growing throughout Cell 4 and the low parts of Cell 5. The higher parts of the dredge fill were colonized by an occasional Chenopodium ambrosioides (Mexican tea) [best guess] or Sesbania drummondii (rattlebox) which matured and died early. The grasses popped up next with Spartina alterniflora (smooth cordgrass), Echinochloa walterii (Walter’s millet), and Schoenoplectus robustus (saltmarsh bulrush). I’m sure there are a few I’m missing.

Figure 4. A new view of the study area from the south side of Cell 5. This view is to the northwest across cells 5, 4, 2 and 1, and shows multiple walkways and containment structures.

Figure 4. A new view of the study area from the south side of Cell 5. This view is to the northwest across cells 5, 4, 2 and 1, and shows multiple walkways and containment structures.

On my way back to the boardwalk and another try at moving the hose, I noticed the birds were still actively feeding, so I found a spot on the walkway that was hidden by a patch of marsh grass and settled myself to take more photos of birds.

Figure 5. The feeding birds ignored me sitting behind my clump of grass, and came fairly close. Greater Yellow-legs on the left, and a least sandpiper with muddy legs on the right.

Figure 5. The feeding birds ignored me sitting behind my clump of grass, and came fairly close. Greater Yellow-legs on the left, and a least sandpiper with muddy legs on the right.

 

Figure 6. We moved the hose away from the dock and containment by hand.

Figure 6. We moved the hose away from the dock and containment by hand.

Around 9:15, just as I was starting to wonder where Timmy and the airboat were, he appeared on the boardwalk to tell me the airboat wouldn’t start. Oh well.

I put up my camera, and while he donned his boots, I went back for the rope I left in the marsh that is connected to the end of the hose. I managed to unkink the hose at the boardwalk, and then walked the rope back around the edge of the marsh where Timmy joined me. Together, we were able to slide the hose to a more satisfactory position, and were ready to dredge by 9:30.

He left to trade out boats and bring the Goose back, and I went to the dredge to get it set up for dredging.

Timmy returned to do some weed trimming and keep an eye on the pond while I dredged. There was plenty of water in the canal and I could make a full swing. Working the dredge by myself, I was back and forth adjusting things while continuing to raise and lower the pump, carrying the controller around with me. As I went to check the gages for about the 4th time, a hornet flew out of the control box. To my horror, it was followed by a crowd of hornets, all pushing each other out of the way for space in the gap. Apparently, the vibration and noise of the hydraulic engine had awakened them out of their winter stupor, and they weren’t happy. Neither was I. I am extremely allergic to wasp stings. Thus began the 2012 Battle of the Dredge. I grabbed a can of wasp spray and proceeded to attempt genocide. It was an hour long battle, a whole can of spray, and I was exhausted, but victorious and unscathed.

Figure 7. A scene of death and destruction, a battleground of epic proportions between me and the wasps.

Figure 7. A scene of death and destruction, a battleground of epic proportions between me and the wasps.

Figure 8. A juvenile scissor-tailed flycatcher entertained me for a brief moment.

Figure 8. A juvenile scissor-tailed flycatcher entertained me for a brief moment.

While relaxing after vanquishing my foe, a bright flash caught my eye. Most birders pull out the binoculars first, but I did my usual thing to pull out my camera to see if I could get a clean shot. I have learned that most unusual sights don’t stay very long, and if I can catch a clean shot, I can always try to ID it later and have documentation/proof or delete it. THEN, I pull out the binoculars. This one stumped me at first, but it turned out to be a juvenile Scissor-tail Flycatcher, without the scissortail.

One lap dredging across the canal and back took me a little over 2 hours, and it raised the water level in the pond by 4 inches within the containment. This did as intended and we spread a good layer of new fill across most of Cell 3, but it also did as expected and popped a few exits under the containment 3 to add a lot of the finer material to Cell 2. No more dredging today.

There was still a good part of the day left, so I went along with Timmy for a mud boat ride into Christian Marsh. The marsh plantings on the terraces look terrific, with lush marsh grass hiding the near bare summits of each ridge. American Coots were present in large numbers, scattering in radiating lines of fountaining foot prints to reassemble elsewhere. We passed a floating flock of about 15 Pied-billed Grebes that immediately dipped under water and disappeared. Several large alligators were placidly cruising or sunning in the late afternoon light. The water was full of fish, large and small, and lots of shrimp that would pop up out of the water in the shallows as we passed.

Figure 9. American Coots water-running away from the boat.

Figure 9. American Coots water-running away from the boat.

Figure 10. An 8-ft alligator warming up on the bank of a terrace in Christian Marsh.

Figure 10. An 8-ft alligator warming up on the bank of a terrace in Christian Marsh.

Friday, November 9

Today’s sunrise was a perfect copy of yesterday. It was cool, clear, and not a speck of clouds in the sky. There was a good north wind blowing today, and I needed to get out while I had enough water to make it home. However, I had plenty of time to check out the dredge site first. Cell 3 had de-watered some so I could see the mud layer we had added. The new fill in Cell 3 is highest at the south end where its 2 inches above marsh level (+2” ML) and at the dock where its +1” ML, with the rest of the cell sloping to about -3” ML at the northeast side. There was a small mixed flock of sandpipers working the exposed new mudflat, but the big flock of feeding birds had moved on.

Figure 11. The water level had dropped just enough to expose the mud laid down the day before. This view is from the dock toward the northeast.

Figure 11. The water level had dropped just enough to expose the mud laid down the day before. This view is from the dock toward the northeast.

Figure 12. Another view of the new mud looking north. One of the scoured exits is at the bottom left of the image.

Figure 12. Another view of the new mud looking north. One of the scoured exits is at the bottom left of the image.

Figure 13. View from the walkway between Cell 3 and 5 looking slightly west of north. This end is higher than the rest of the cell and is covered with mud cracks as the new fill consolidates. The square hole was the location of the sunk pontoon that we pulled out last week.

Figure 13. View from the walkway between Cell 3 and 5 looking slightly west of north. This end is higher than the rest of the cell and is covered with mud cracks as the new fill consolidates. The square hole was the location of the sunk pontoon that we pulled out last week.

The next stop was the test site, where we first practiced with our new dredge. I haven’t visited this site since mid-summer. As I approached the boardwalk, I could see an enormous flock of ducks across the outer pond. As I stepped out of the reeds that hid me from the pond, the nearest ducks became nervous, and took off in front of me, then swirled and landed, which excited other ducks that took off, swirled and landed, and this restless movement continued for as long as I was there. I was so amazed that I took photos and video: http://youtu.be/nfvBB_3DYBA

Figure 14. An enormous flock of ducks were near the test site, and would take off, swirl and land in continuous waves as long as I was within sight.

Figure 14. An enormous flock of ducks were near the test site, and would take off, swirl and land in continuous waves as long as I was within sight.

The test site looked to be in good condition. We had not filled it completely before we had moved the dredge to start working on LSU’s experimental area, and the few inches below marsh level seems to be a deterrent in the rate of natural marsh colonization. The Scirpus was spreading in a few places along the perimeter, but not very far. Spikerush was the dominant species in the center of the cell and the Bacopa we had planted was either dormant or gone.

However, the smooth cordgrass (Spartina alterniflora) that Timmy had planted next to the boardwalk and reed containment was doing exceptionally well, and had spread from sprigs to a band a good 6ft wide, spreading through the reed containment and even under the boardwalk. Some of the roseaucane (Phragmites) that was cut green and bundled for containment had sprouted and were growing right next to the dock. This was just as we had intended: the marsh grass would hold the reeds in place, and would eventually make a natural marsh containment as the bundled reeds deteriorated.

Figure 15. The test site (with ducks in the outer pond) looked to be in good shape. The Spartina alterniflora next to the boardwalk had spread from sprigs to a band 6ft wide, growing through the containment and under the boardwalk. View is to the south.

Figure 15. The test site (with ducks in the outer pond) looked to be in good shape. The Spartina alterniflora next to the boardwalk had spread from sprigs to a band 6ft wide, growing through the containment and under the boardwalk. View is to the south.

Figure 16. A view of the test site to the west from the end of the boardwalk, showing Scirpus along the perimeter and spikerush covering the interior.

Figure 16. A view of the test site to the west from the end of the boardwalk, showing Scirpus along the perimeter and spikerush covering the interior.

Note: Google Earth has April 2012 photography of our dredge operations at: ..LSU Dredge Study.kmz

 

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
225-768-0921 office, kwestphal@audubon.org

 

 

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