Estuary Project 2011

Historically the Tryon estuary housed lobster packing plants, fishing fleets, and had barges which traveled up river to the lumber mills and shingle mills. Presently, the estuary is so filled with silt that even a shellfish dory has to go out on high tide if it wants to launch from the boat ramp on the Abateau Bridge. The river has loss much of it use as a recreational boating location, with canoes being hung up on the sediment on low tide.

This is a 4 site project with the goals of the project being:

1. Stabilize sediment

2. Deter bank erosion

3. Reduce sea lettuce

4. Deepen navigational channels

5. Restore aquatic habitat

 

Site 1 Objectives: Deepen Navigation Channels and Silt Collection

Figure: Site 1, 2011

Site 1 is a cove brush mat located by the Abateau Bridge.  It was made from over 1500 Christmas trees donated and delivered by Label Construction and long fir poles donated from a local wood lot.  The long poles were stuck into the mud by drilling a hole through the post, placing a steel rod through the hole and jumping on the rod.  This was repeated until the post was driven well down into the mud.  Once secure, the Christmas trees were attached to make the bulk of the mat.  The mat was completed in early August but will continue to be monitored for the coming years.  Measuring sticks record the amount of sediment catches.  The last reading was in November where over a foot of sediment was trapped.

Figure: Brushmat Creation, 2011
Figure: Silt Trapped, 2011

The mat is very successful in catching sediment, and is also successful in deepening the channel on the outside.

Site 2 Objectives: Sea Lettuce Capture and Navigation Channel Deepening

Site 2 involved the creation of a two-piece brushmat, located on a small tributary by Best’s Bridge on Tryon Point Road; these brushmats will be running parallel with the estuary channel. These brushmats were constructed as a causeway, leaving a 25 foot gap between the two pieces. The objectives of this component are to remove sea lettuce, stabilize silt, deepen the channel, and remove excess nitrogen from the water. This particular portion of the overall estuary project was not as successful; it is expected that the gap between the two brushmats was too large to adequately deepen the channel. Tryon watershed group hopes that as the mats solidify in the future, the energy will go towards deepening.

Figure 3: Site 2 Component

Site 3 Objective: Bank Stabilization

This component is a bank stabilization project located at the end of the Tryon Point Road. Bank erosion is a serious issue in the Tryon watershed, and methods of mitigation are being sought across the Island by various groups. The effects of breakwaters were tested during 2011. Several methods of stabilization were tested: 1) jute matting; 2) cement breakwaters; 3) sandstone breakwaters; 4) brush bank protection; and 5) planting of native shrubs (wild rose, bayberry and serviceberry). 34 out of 35 planted shrubs survived and are growing successfully.

Figure: Site 3, October 2, 2011
Site 3, October 2, 2011

Site 4 Brush Mat – Silt Collection

This project component was not completed due to unnecessary risk to participants.

Project Summary – 2011

Plans are being made to continue this project in the future. Permits have been submitted to the provincial government in 2012 to continue work in Sites 1 and 2.

Site 1 will have additionaly measurement stakes installed, as they were removed during the movement of winter ice. Outer edge will be reinforced, and material will be added to low areas. Monitoring will continue until such point that mat has established itself as an integral part of the estuary bank.

Site 2 will also be reinforced; the south section will have new poles installed to replaced those removed during the winter months. Additional material will be added behind the mat to aid in sediment catchment and mat stabilization. Monitoring will also continue in this area.

Site 3 will be monitored to determine the long-term success of the shrubs.

The Tryon River Watershed Cooperative would like to thank Environnment Canada for their financial contribution towards this project.

For further information, please contact Kellie Lockhart via sswa@sswa.ca

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