The document outlines a project for salt marsh restoration in Hook Creek Park, aimed at addressing vulnerabilities caused by sea-level rise and erosion through thin layer sediment placement and habitat enhancement. It includes ecological assessments of salt marsh conditions across NYC, project goals, construction timelines, and post-construction results showing successful vegetation regrowth. Lessons learned emphasize effective methods for sand placement and the importance of public outreach in restoration efforts.

1. Thin Layer Sediment
Placement Salt Marsh
Restoration in Hook Creek
Park
November 30, 2023
Jamaica Bay Task Force

2. 2
Almost Half of NYC is Green

3. 3
Half of NYC’s Wetlands and Streams are in NYC Parks

4. Threats to NYC salt marsh
In NYC, salt marsh accretion and migration are restricted by
accelerated sea-level rise and barriers from development.
Citywide our marshes are vulnerable to shoreline and interior erosion
due to sea-level rise, storm surge, sediment starvation, and high
nutrient loads.
We want to address some of these threats through thin layer
sediment placement, marsh edge restoration, and protecting and
managing migration zones.

5. Ecological Assessment at 25 salt marshes across NYC
Long
Island
Sound
Staten
Island
Jamaica Bay
Desktop Analysis
o Historic Loss Analysis
o Sea Level Affecting
Marshes Model (SLAMM)
Rapid Ecological
Assessments
o Mid-Atlantic Tidal Rapid
Assessment Method
(MidTRAM)
o NAC Salt Marsh
Assessment (NACSMA)
Conditions and
vulnerability indices

6. Alley Creek Inner
Alley Creek Outer
Hutchinson Inner
Hutchinson Outer
Pelham Bay Cove
Pugsley Creek Marsh
Turtle Cove
Udall's Cove Marsh
Westchester Creek
Four Sparrow
Fresh Creek Marsh
Idlewild Marsh Inner
Idlewild Marsh Outer
Spring Creek
Arlington Marsh
Fresh Kills Marsh
Lemon Creek Inner
Lemon Creek Outer
Neck Creek Inner
Neck Creek Outer
Richmond Creek
Saw Mill Creek Inner Saw Mill Creek Outer
W. T. Davis Inner
W. T. Davis Outer
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
-1.5 -1 -0.5 0 0.5 1 1.5 2
Long Island Sound
Jamaica Bay
Staten Island
Lower Condition / Lower Vulnerability Lower Condition / Higher Vulnerability
Higher Condition / Lower Vulnerability Higher Condition / Higher Vulnerability
Priority site for
protection
Priority site for restoration
Condition
Vulnerability

7. Need for increased marsh
surface elevations
8.9
4.8
2.1
0.7 0.7
0
2
4
6
8
10
Priority
Area
(acres)
Field Data
• % low marsh
• % bare ground
• Breeding birds
Desktop data:
• Future marsh loss (SLAMM)
• Accessible for sediment
placement
Photo: Patty Doer, TNC-NJ Idlewild Marsh, Queens

8. Project Location
8
Completed
Planned

9. Site analysis and design development
9
Project Goals
• Raise marsh surface elevation
• Enhance habitat for breeding
birds
• Evaluate sediment placement
methods

10. 10
Construction

11. 11
December 2022
March 2023
June 2023

12. 12
December 2022
March 2023
August 2023

13. 13
December 2022
March 2023
November 2023

14. Post-construction results
14
2.5’ (0.5’-1’ depth) - LM
3.0’ (1’ depth) - HM
4.0’ (1.5’ depth) HM
0.7 acres of high marsh (HM)
0.3 acres of low marsh (LM)

15. Preliminary post-restoration observations
• No major issues post-restoration
• Planted plugs survived and are growing
• Existing vegetation growing through thinner
areas of sand
• Crabs and birds present
15
High Marsh Low Marsh

16. 2.3
1.5
3.1
2.0
2.2
1.6
3.1
2.0
3.0
2.3
3.2
2.1
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
RestoredHM RestoredLM ReferenceHM ReferenceLM
2023
Post-restoration
Average
Plot
Elevation
(ft
NAVD88)
2021 2022 2023 MHW MHHW
Post-restoration monitoring results
16

17. 2.3
1.5
3.1
2.0
2.2
1.6
3.1
2.0
3.0
2.3
3.2
2.1
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
RestoredHM RestoredLM ReferenceHM ReferenceLM
2023
Post-restoration
Average
Plot
Elevation
(ft
NAVD88)
2021 2022 2023 MHW MHHW
Post-restoration monitoring results
17

18. Lessons Learned
• Pumping sand from upland works
• Sand stable on marsh platform, but not in ditches
• Coir log effective at containing sand, but maybe not
necessary – use turbidity curtain instead
• Public outreach is important (as is fencing)
• Existing plants grew through thinner areas of sand (~6
inches)
18

19. Next Steps
• Continue monitoring and maintenance at Hook Creek site
• Construct additional sand placement restoration work in
Idlewild Park
19

20. Thank you!
christopher.haight@parks.nyc.gov
Christopher Haight