Gowanus Canal aerial view

Gowanus · Research · 2026

Flooding-driven
Pollution
in Gowanus

As sea levels rise and storms intensify, the Gowanus Canal becomes a conduit for contaminated water — threatening public health, ecology, and infrastructure.

Explore the research

Part 2

The Problem: Pollution Mechanisms and Impact

How contamination spreads during flood events, and where it remains after the water recedes.

0M
Gallons / Year

The Unsolved Reality

Historically, over 377 million gallons of raw sewage dumped into Gowanus annually. Even after the ongoing billion-dollar EPA retention tanks are completed, models project that at least 115 million gallons of toxic Combined Sewer Overflow (CSO) will still flush into the canal every single year.

Source: Gowanus Canal Conservancy (GCC) - Open Sewer Atlas

Official Damage Assessments

Health Risk

EPA

Multiple Enforcement Actions Address Cleaning Up Contaminated Sediments

"Addressing the severe contamination in the Gowanus Canal... mitigating exposure to hazardous substances like coal tar, heavy metals, and PCBs affecting local communities."

Read Official Source

Ecological Risk

NOAA

Gowanus Canal Damage Assessment, Remediation, and Restoration

"Decades of industrial pollution have severely degraded the canal's ecosystem, threatening marine habitats and degrading sediment quality across the basin."

Read Official Source

Urban Risk

EPA

EPA Reaches New Milestone in Gowanus Canal Superfund Site Cleanup

"A major component of the cleanup is the construction of two large underground retention tanks designed to intercept and store millions of gallons of sewage during rainstorms."

Read Official Source

During the Flood: Spreading Mechanisms

Overflow Process

Backflow Process

Water Depth
Shallow
Moderate
Deep
Pollution Level
Low
Medium
High
Very High

Overflow Process (Flooding)

During a flood event, the highly toxic sediment pollution deposited at the bottom of the Gowanus Canal is easily stirred up. As the water level rises, this mixed contaminated water overflows directly from the canal into the surrounding urban space.

Backflow Process (Receding)

When the floodwaters begin to recede back into the canal, a significant amount of the pollution does not recede with the water. It is left behind, trapped in the urban fabric where it takes a very long time to safely dissipate.

The Aftermath: What Gets Left Behind?

Black Mayonnaise

"Black Mayonnaise"

The noxious sludge famously lining the canal bottom. When deposited on streets and drying out, its contaminated dust easily becomes airborne and infiltrates local basements.

Read Cover Story →
Heavy Metals and PAHs

Heavy Metals and PAHs

Residual concentrations of Lead, Arsenic, and Polycyclic Aromatic Hydrocarbons (PAHs) persist in the urban soil long after the floodwaters have completely drained.

EPA Press Release →
Contaminated Soil

Extreme Persistence

While floodwater retracts within hours, sediment pathogens and chemicals take years to dissipate naturally, turning temporary floods into long-term chronic public health hazards.

NY Conditions Report →

Context and Vulnerability: Proposed vs Flooded

← Proposed Future Vision
Simulated Post-Flood Impact →
Normal View Flooded View

← Drag the handle to compare →

Part 3

The Science: Simulation and Modeling

Utilizing data and agent-based modeling to predict the severity of the crisis.

Methodology

GAMA Agent-Based Model

Our simulation dynamically maps extreme rainfall, continuous canal overflow, and complex urban topologies (DEM). Water flows anatomically across the terrain grid, constrained by real-world building massing and specific surface runoff coefficients.

Temporal Frame 150 Ticks Total
20 Ticks Storm 130 Ticks Recession
View GAML Source
Topography
DEM 2263

≈ 1-Foot High-Resolution Elevation Data

Cellular Size
Dynamic Grid

≈ 2m × 2m Urban Micro-Catchment Scale

Rain Intensity
0.2 units/t

≈ 100-Year Extreme Storm (3+ in/hr)

Canal Pollution
Level 7.0

≈ Extremely Toxic Raw CSO Sewage Discharge

Contagion Rate
Mobility 1.4

≈ Rapid Tidal Backflow Spreading Rate

Green Absorb
0.08 / cell

≈ Natural Porous Soil Retention Capacity

Intervention Modeling Console

Interactive hydrological simulation mapping four distinct physical intervention strategies under identical storm constraints.

Drag to Pan
Baseline Scenario

No interventions active. Severe flooding occurs, driving pollutant deposition deep into vulnerable low-lying urban zones.

Strategy 1: Physical Block

Hard engineered barriers completely halt initial storm surges but disrupt critical tidal ecosystems inside the canal.

Strategy 2: Permeable Greenland

Vast porous networks absorb minor runoff effectively, though they inevitably become saturated during extreme events.

Strategy 3: Comprehensive

A hybrid layered approach balances resilient physical defense with ecological integration and absorption.

Part 4

The Solutions: Interventions and Testing

Testing physical and green interventions in our models to measure their impact on pollution reduction.

Strategy 01

Physical Block

A hard engineered barrier system to prevent canal water from entering streets. Halts localized swelling but triggers severe upstream consequences.

BASELINE
PHYSICAL BLOCK
Strengths
  • • Immediate flood cessation
  • • Predictable protection zone
Weaknesses
  • • High infrastructure capital cost
  • • Severe ecological flow disruption
  • • Obstructs canal sightlines
Pollution Discrepancy Data
Pollution Data

Strategy 02

Permeable Greenland

Porous parks and infrastructure designed to absorb runoff naturally, offering ecological benefits but lacking raw defensive capacity.

Strengths
  • • Vital ecological co-benefits
  • • Lower installation cost
  • • Multi-use public spaces
Weaknesses
  • • Saturated rapidly in storms
  • • Intense ongoing maintenance
BASELINE
PERMEABLE GREEN
Flooding Spread Variance
Flooding Data
Pollutant Soil Retention Analysis
Pollution Data

Strategy 03

Comprehensive Solution

A high-fidelity hybrid approach stacking engineered physical defenses with expansive distributed green infrastructure.

BASELINE
COMPREHENSIVE
Strengths
  • • Dynamic adaptive resilience
  • • Layered multi-scale defense
  • • Balances ecology & geometry
Weaknesses
  • • Complex agency jurisdiction
  • • Massive sustained funding
System Flood Reduction Efficacy
Flooding Data
Toxicity & Pollution Mitigation
Pollution Data

Part 5

Take Action: Community and Policy

Translating hydrological research into resilient, equitable outcomes.

Concerned Problem

Agencies see the data. Residents need to see the risk.

The concern is already loud:

News Gothamist

Residents press state & feds to clean up toxic fumes

X @infogobn

"The remediation plan will put residents' health at risk."

Facebook Voice of Gowanus

Community health survey on legacy toxicants (TCE, BTEX)

Community Health Risk

Legacy pollutants + dust + construction exposure

Two lines of defense:

During Construction

Controlled excavation · Covered transport · Safe scheduling

Long-Term

Air-quality sensors · Green buffers · Health reporting

From Disclosure to Monitoring

Who does what, at each step of the process

1

Disclose Risk

Publish flood and contamination hotspot maps for streets, parks, and canal edges.
WHO LEADS U.S. EPA
NYC DEP
2

Gather Concerns

Collect resident input on health, green space, and construction impacts.
WHO LEADS Brooklyn CB6
Gowanus CAG
3

Review Options

Compare hard barriers, green landscapes, and hybrid solutions side by side.
WHO LEADS Residents
Planners
Gowanus Canal Conservancy
4

Pilot Solutions

Test interventions near the canal first before scaling city-wide.
WHO LEADS NYC agencies
Waterfront owners
Engineering contractors
5

Monitor Safety

Publish ongoing updates on water, soil, and public-space safety.
WHO LEADS EPA + NYC DEP
Community partners

PART 6

Future Vision

The future of Gowanus is our choice. We choose a more resilient and cleaner Gowanus.

Future Vision without Mitigation

Future Vision without Mitigation

Future Vision with Mitigation

Future Vision with Mitigation