Proposed Giant Tidal Gates by the Throgs Neck Bridge and their Impact on the North Shore

On February 19th, the Army Corps of Engineers will release an interim report that will lay out their conceptual plans for protecting New York City from future major storms. This will be followed by public meetings (yet to be announced) in March and April. This article will bring you up to speed on what we know so far.

Late last Summer / early Fall, we learned that the Army Corps of Engineers was proposing a number of alternatives which included the construction of massive tidal gates by the Throgs Neck Bridge, which when closed, would raise water levels behind the gates (called “induced flooding”). Despite the potential for this impact on north shore communities, no hearings or public meetings had been scheduled on the north shore. That changed when we contacted Rep. Tom Suozzi who in turn convinced the Army Corps to hold a public meeting at the U.S. Coast Guard Academy on October 23rd.

At that meeting, the Army Corps committed to studying the impact of the induced flooding on our communities and to hold future meetings in our area. The extent of their study into induced flooding was not clearly defined. We are hoping that it will be in the upcoming report.

The following is a synopsis of the October 23rd public meeting. It was prepared from notes taken by Sarah Deonarine of the Manhasset Bay Protection Committee and Eric Swenson of the Hempstead Harbor Protection Committee.

Rep. Tom Suozzi pointed out that following nitrogen, the top concern voiced at last year’s L.I. Sound Summit was sea level rise. Flooding is a real concern for north shore communities. 

The Army Corps’ Bryce Wisemiller then pointed out that post-Sandy, the Corps completed aNorth Atlantic Coast Comprehensive Study,which identified focus areas for further study. The New York and New Jersey Harbor and Tributaries (NY NJ HATS) is the largest of the focus area studies; it covers 2,150 square miles, 900 miles of shoreline, 25 counties, and 16 million people. Because the study area is so large, the Corps has two non-federal partners (they always have to have one): NJ DEP and NY DEC.  And New York City is a “major player.” Without the protections envisioned in this study, a 100-year storm, 227,000 structures would be impaired and 300 square miles would be flooded.

The Corps emphasized that this is just the beginning of the process and that they want to study and collect information from others.  They have concept plans developed for the alternatives based on best guesses and assumptions but are still looking for public comment and input. They requested that audience members send them any information that they may not have.


The Corps’ presentation started with a map that shows only the fatalities from Sandy, because those are “the resource that cannot be replaced.”

The Corps started with definitions and explaining their process: “Coastal Storm Risk Management (CSRM)” – it’s risk management, not flood control.  No matter how high the wall is, it will be overtopped eventually. They can reduce the number of flooding, divert water, store the water, stop the water with a localized measure – structural.  Non-structural is when we don’t change the way it floods, but try to get structures and people out of harm’s way (elevating houses, flood-proofing, buy-outs, etc.) – not changing the flooding regime (non-structural).  

The Corps has 6-step iterative planning process.  Evaluate alternatives:  has to be environmentally acceptable, cost has to be less than the gains. The Corp’s revised schedule is based on receiving a waiver to their “3x3x3” rule (studies must be completed within 3 years, cost no more than $3 million, and involve no more than 3 tiers of administration): 


o   January 2019 – “Interim Report” (not any sort of statutorily required document, but will include summaries of their work thus far, and will respond to all scoping comments received by 11/5/18) – concept plan/mock-up

o   Spring 2020 – Draft EIS and Feasibility Study (here they will narrow down the alternatives – as opposed to the original plan to narrow down this fall before the Draft EIS)

o   Comments can be taken on the Interim Report and the Draft EIS/Feasibility Study

o   There will be some sort of outreach event(s) after the Jan. 2019 Interim Report and after the Spring 2020 deadline – Corps does not know what format yet

o   The Corps recently added CT stakeholders to its mailing list on the project.  Stakeholder outreach list is over 3,000 and growing.


There are six alternatives. #s 2 – 4 are in-water structures. #5 is land-based structures. All alternatives are designed for a 100-year storm with increases for wave action:

1– baseline/ no action alternative (note: they will show what others are doing including other Army Corps projects in the study area).

2 & 3ais for a surge barrier just west of the Throgs Neck bridge.  Planning to the 1% storm event (in 100 years, the 1% storm would be one in 10 years).  Alternative 2 has the largest number of surge gates.  They referred to the “Study Area Proper.” This also included surge gates closing off NY Harbor from Sandy Hook NJ to the Rockaways.

3a– tide gates go further back into the estuaries.  Surge gates are very expensive.

3b – does not have as many surge gates.

3b & 4are very similar, the differences are on Staten Island and NJ

5– only on-land based measures (sea walls along the shoreline, etc.)

Storm risk gets worse for the Atlantic Ocean areas as next 100 years pass (worse than for the north shore).  Being designed to 100 year event + mid-level SLR projection + wave run-up

Surge barrier examples from around the world:  

  • Surge gate in Louisiana was $3B
  • Thames River in London, structures on the bottom rotate up, they don’t get much wave action, so it works there.  
  • Largest moving structure in the world is in Rotterdam, the Netherlands.  Sector gate comes out from the land and is sunk down.
  • As the surge gates won’t be closed for every event, high frequency events may impact areas behind a surge barrier.

Nothing is easy, given the urbanization and the coastal storm risk in the area.

NEPA Process:

They will be doing a tiered environmental impact statement (EIS), the most robust NEPA analysis. Because of the size and complexity, they will consider environmental impacts at every stage, but won’t be as in-depth until they get further along in the process.  During the feasibility study phase (conceptual), will have a Tier 1 EIS.  Then tier 2 based on more detailed designs, etc.

No plan can be constructed until permits are in place, and they can’t get permits until EIS is completed.  There will be lots of public input through this long process.  At the end of the process, a Chief’s Report will be prepared which will then be sent to Congress. Congress then decides what will happen based on the Corps reports and if the non-federal sponsors agree (New York, New Jersey and NYC). There was no mention of Connecticut. Congress has to authorize the project and fund it, which alone is probably a multi-year process.  On the current scheduled, they anticipate making a recommendation to Congress in Summer 2022. Construction may not begin until the 2030s.

Public comments on this study are due by November 5th.

Question & Answer Take-aways:

Army Corps is very concerned about “induced flooding” behind the barriers (i.e. the north shore). Induced flooding would have to be dealt with as part of that alternative – all impacts have to be mitigated.  This could shut-down an alternative.

The January report will only present information they have, no decisions/selections will happen at that time.  Right now they are throwing out a lot of assumptions and best guesses. Developed a general cost and benefit that they created, will be in the January report.  As they go through the process, these will change.

Modeling of impacts outside the alternatives will be done for each alternative.  Reflection of waves on gates is part of modeling analysis that will have to be done in the future.

Storms send surge a couple days before the storm hits, so the surge gate would be closed a day before that.  Transportation and navigation already stop for big storms, but the details for protocols have not been worked out yet.

Saddle Rock’s Mayor stated that they’ve had four 100-year storms in the past 5 years:  Irene, Sandy, something else, and the March Nor’easter. He felt that adding induced flooding on top of this could devastate his village and that places like Bayville would “become a sump”.

FEMA money has not been considered, they only identified those projects authorized shortly after Sandy.  If there needs to be a look at specific areas, that would come through non-federal partners.  ßThis was Sarah Deonarine’s (Manhasset Bay Protection Committee’s) question, she was attempting to get at the point that their alternatives would counteract federal money being spent in Manhasset Bay.

Explain the waiver to the “3by3by3” rule:  the schedule is assuming that there is a waiver. The Corps has a motto that a project has to be done within 3 years, $3m, and 3 levels within vertical team.  This process in this area is going to exceed these restrictions.  HQ is supporting the waiver to go through, but want to make sure that there are “checks” along the way.  The waiver still needs Secretary’s approval.

Did you consider other alternatives, would you consider other alternatives?  Other alternatives were considered and will be included in the iterative process, especially if there are other ideas suggested.  Right now, they’ve just been focused on the 6 shown here and studies done prior to this.  If anyone has ideas/suggestions, send them in. 

Eric Swenson (Hempstead Harbor Protection Committee) asked how far east the Corps would study in terms of induced flooding. They did not give a direct answer.

The January 2019 draft is just to say “what we’ve been doing,” and is part of being transparent.  The report will consolidate all the information they have now and the alternatives they have looked at to display what they’ve done, and identify what additional information is needed.  They acknowledge that this information is going to have to be followed up.  Spring of 2020 should be the draft report and EIS.

The study alone may cost up to $19M and take up to 6 years [half federal money, half non-federal money (NJ &NY)].

They are considering establishing a steering committee to help with outreach as well as a technical advisory group. It was pointed out that the Long Island Sound Study already has a Citizens Advisory Committee and a Technical Advisory Committee, and both are comprised of stakeholders from around Long Island Sound. They stated that they would consider using them.

Eric Swenson (Hempstead Harbor Protection Committee) also asked if the study would consider and comply with the recommendations in the Long Island Sound Study Comprehensive Conservation and Management Plan. They said that they would.

One person stated that the depth of the water at the Throgs Neck Bridge is 100 feet and asked if the tidal gates would be that tall. The Corps stated that the area where the gates would be installed is not that deep but they could not give the actual depth. The gates would have to be as deep as the water.

The Corps also stated that Long Island would be included in future public meetings. 

Here is a direct link to the Army Corps slides shown at the presentation

Stay tuned….

Ocean Acidification – What It Is, How It Affects Us, and What Can Be Done?

You may think that “ocean acidification” has little direct connection to our local bays and harbors. The truth is that its impacts are greatest in shallow coastal waters.

Ocean Acidification (a lowering of the pH in our waters caused by increased CO2 in the atmosphere) causes, among other things, less calcium carbonate in the water that shellfish larvae and others require to grow their shells. After spending years improving our water quality and re-opening 2,500 acres to shellfishing for the first time in 45 years, this is obviously a concern in Hempstead Harbor.

Last night, the NYS Ocean Acidification Task Force held its second meeting – this time in Nassau County.  Three very interesting presentations were made, which are summarized below.

Dr. Chris Gobler (Stony Brook University School of Marine and Atmospheric Sciences (SoMAS))

  • Latest CO2 reading – 1/11/19 is at 409.44 ppm (400.0 was deemed to be the threshold).
  • CO2 levels are increasing faster than originally predicted
  • Calcifying organisms are vulnerable (shellfish, etc.)
  • 2012 – most of NYSs fisheries are calcifying organisms
  • Larval stages are most susceptible. When they are born, they have no shell and need to extract calcium from the water in order to grow them.
  • Before the industrial revolution, CO2 levels were 250 ppm.
  • Above 390 ppm affects shellfish.
  • It does not just affect survival rates, but also growth rates.
  • Fish are also sensitive to Ocean Acidification (OA). Larval fish do not survive as well.
  • The same processes that lead to hypoxia (nutrient loading) will also lead to increased acidification.
  • We see more severe OA in coastal waters than in the ocean.
  • It is seasonal – Spring to Summer is highest.
  • In summer of 2014, the western LIS was actually acidic (below pH 7.0). 8.0 is normal.
  • Where you have low dissolved oxygen (DO), you have high OA.
  • During nighttime, DO is lower and OA increases, particularly in shallow estuaries.
  • About 5 years ago, almost nothing was known about the connection between low O2 and OA.
  • In one experiment juvenile clams were able to grow with low oxygen. They also did alright with low pH. But when both are combined, their growth was slowed. In the real world, you have both together.
  • Multi-trophic aquaculture – growing seaweeds and shellfish together can help.
  • NYS does not regulate for pH – only DO.
  • Growth of seaweeds can be detrimental to sea grasses but a help to shellfish.
  • Where there is high CO2, sea grasses may benefit if there are no seaweeds growing.
  • Macroalgae take CO2 out of the water.  This is based on lab experiments. Then you’d need to harvest it. Kelp is one viable option.
  • Carbonate goes down as pH goes up. You have to also measure alkalinity or DO when you measure pH.

Kyle Rabin (Long Island Nitrogen Action Plan, Long Island Regional Planning Council)

  • The Long Island Nitrogen Action Plan (LINAP) is a multi-year initiative to reduce nitrogen in surface waters and groundwater. Partnership between DEC, LIRPC, and two counties.
  • They have monthly conference calls for updates and coordination.
  • Workgroups have been formed to address specific aspects (e.g. fertilizer).
  • Part of their mission is to assess nitrogen levels, determine sources, and ID reduction targets.
  • The NYS Ocean Acidification Task Force (OATF) and LINAP compliment each other.
  • Suffolk’s initiatives:
    • Subwatersheds wastewater plan
    • Septic system improvement plan
    • Septic / Cesspool Upgrade Program Enterprise – up to $20,000 is available to each homeowner
    • Sanitary Code changes
    • Sewering projects – including SC Coastal Resiliency Initiative – eliminating cesspools in sensitive areas. Public referenda are being held in 3 areas today.
    • Harmful Algal Bloom Action Plan – created in 2017. Still being developed.
  • Nassau’s initiatives:
    • Subwatersheds planning – SoMAS is working on it using the same methodology as Suffolk.
    • South Shore Water Reclamation Facility (Bay Park WWTP) upgrades
    • South Shore Water Reclamation Effluent Diversion Project (19 Billion gallons a year of sewage will no longer be discharged to the Western Bays).
    • Long Beach Wastewater Diversion to Bay Park
    • Point Lookout Sewer Study
    • Septic Improvement Program
      • 60,000 septic systems on north shore
  • Suffolk County Water Quality Improvement District Study – looking at establishing it. RPF has been released.
  • LINAP Fertilizer Management Workgroup – recommendations are being finalized. Apply to homeowners and professional landscapers. Will be published in LINAP newsletter.
  • South Shore Estuary Reserve (SSER) Western Bays Water Quality Monitoring – about to begin. Using a university. 
  • STEM Challenge – Grades 6-8. LI Water Quality Challenge – stormwater treatment or low impact landscaping
  • Nutrient Bioextraction Initiative – seaweed and shellfish aquiculture to remove nitrogen in coastal waters. NYC DEP is looking to use ribbed mussels for this purpose as they are not susceptible to poaching from uncertified waters.
  • Nitrogen Smart Communities – municipalities need to meet certain goals. Will be a pilot project
  • Water Reuse Advisory Workgroup – workgroup was established. Roadmap produced. Golf Course irrigation being looked at.
  • LI Water Quality Data Sharing System – one stop location for all data. Being developed. Over 60 entities collect data on LI.
  • Outreach – monthly newsletter with 1,700 subscribers. 
  • He would be glad to talk to the Protection Committees about their initiatives.

Dr. Frank Roethel (SoMAS)

  • OA has long been known in lakes and streams.
  • In some areas, they pump lime slurries into the waterbodies to reduce acidification.
  • Lime has benefits for lakes – inexpensive, available, non-toxic, natural mineral, easy to distribute, dissolves in water.
  • Very few studies on marine water. 
  • We have 14 WWTPs and Power Plants that all have discharges to marine waters. You could use them.
  • New commercial construction in NYC – stormwater management designs.  Stormwater is directed to large holding tanks and eventually discharged. These could also be used.
  • East River and west side of Jamaica Bay are two of the worst areas. There are major facilities that discharge about 1+ billion gallons a day into these areas. 
  • Highly alkaline liquids – sodium hydroxide – readily available, easy to integrate into existing systems, highly corrosive
  • Highly alkaline solids – lime – available as a waste product of scrubber residual from Waste to Energy facilities and coal fired plants – currently disposal costs on LI = $60 per ton.
  • This could reduce the rate of acidification.
  • To halt the increase in acidification – requires new technology and investment.
  • To reduce acidification – not achievable in our lifetime.
  • Estimate the amount of sodium hydroxide (NaOH) (ph 13) needed to affect pH – Assuming effluent is currently1 billion liters at pH 6 and if the goal is to raise the pH to 7, you would need to add 900 liters (=240 gallons).  Is NsOH too corrosive for wastewater treatment plant workers to handle?
  • If you use the same calculation and extrapolate to all NYC WWTP plants, you would need about 900 gallons per day. 
  • Other potential strategies:
    • Portland cement manufacturing 
      • Portland cement is major contributor of CO2 emissions in the US and worldwide (7% of all C02)
      • 90 million tons of Portland cement is produced in US / year
      • In NY we use 3 million tons / year of Portland cement
      • 1 ton of Portland cement produces 1 ton of CO2
      • There are substitutes for Portland Cement
        • Pulverized glass – has same pozzolanic properties as Portland cement
          • Supports glass recycling
          • Saves landfill space
          • Replacement of a percentage of Portland cement can result in CO2 reduction
          • Encourages sustainable construction
          • We don’t know yet how durable it will be as compared with concrete over the long term.
          • If there is an expanded bottle bill, perhaps some of those nickels can be directed to exploring this.
    • Shell grinding
      • cost effective
      • no adverse impacts
      • whole shells promote regrowth
      • dissolution is a function of particle size
      • optimal grain size would be a function of local conditions.
    • Reduce use of chlorine as a sewage treatment plant disinfectant
    • De-chlorination before discharge
    • Sediment modification (put clean sand or crushed concrete or crushed glass on top of sediments)
    • Enhancing marine vegetation
  • Moving forward, we need more research and demonstration projects and legislation as well as partnerships with industry.

Fertilizing on Long Island – Changes May Be Coming

As you may have read, there is a serious problem of algal blooms that are threatening Long Island’s waterways and the various causes and problems. Fortunately Hempstead Harbor has fared better than most but the threat is still there. This article will focus on one potential cause – overuse of lawn fertilizer – and changes that may be coming.

In Hempstead Harbor, computer modeling by The Nature Conservancy shows that 15 – 20% of the nitrogen in the harbor is from over-fertilizing. While part of the problem is applying more fertilizer than the plant roots can take up or applying it just before a rainstorm where it washes off and down into storm drains, some believe that part of the problem may be the composition of the fertilizer itself.

 Over the past few months, I have participated in a workgroup convened by the NYS Department of Environmental Conservation that has been looking into new regulations regarding residential lawn fertilization on Long Island. It is very possible that legislation will be introduced this Spring in the State Legislature that will change the composition of fertilizer sold on Long Island.

The workgroup that has been addressing this includes fertilizer manufacturers, retailers, landscapers, environmental organizations, government agencies, and others.

The latest recommendations (January, 2019) are not final but include limiting the amount of nitrogen in fertilizer so that no more than 0.6 pounds of nitrogen are applied per 1,000 square feet and that at least 50% of the nitrogen in the bag is non-water soluble (i.e. “slow release”). The 0.6 pound limit would make this the lowest in the nation (most states are at 0.9 pounds including New Jersey and Maryland). At the same time, the maximum annualapplication rate would be 1.8 pounds per 1,000 square feet, meaning that you could apply the fertilizer no more than 3 times a year.  Currently, many fertilizer manufacturers have a “4 step” program. That would now become a “3 step” program. Scotts already makes a “3 step” program for parts of the country.

Further, no fertilizer could be applied between November 1st and April 1st (the exact dates vary slightly at present in Nassau, Suffolk, and New York State rules). During these months, plants have largely gone dormant and do not take up fertilizer anyway.

To ensure that this is adhered to, retailers would be required to remove the product from their shelves during this period.

At least one manufacturer (Scotts) has said that they can produce such a product for Long Island. The proposed law would provide for about a two-year window to produce it.

Some landscapers believe that the 0.6 pound limit is not sufficient for residential turf grass and that this will invite diseases for which pesticides or fungicides would be needed. Others claim that once a lawn is established, that very little fertilization is required. Advocates of the 0.6 pound limit point out that leaving the grass clippings on the lawn (such as with a mulching mower), returns nitrogen to the plants.

If you do fertilize, the best times to fertilize are April through June and September through October.  LIGHTLY water in the fertilizer after applying it.  If you live on the water, do not apply within 20 feet of the shore unless you use a drop spreader. Also make sure to sweep up any fertilizer that may land on driveways or sidewalks to prevent it from reaching storm drains. 

Remember, that everything you do (even if you live miles from the harbor) can impact the quality of our water. Keeping it clean is a responsibility that we all share.