On September 1, 2021, the remnants of Hurricane Ida dropped roughly 5 to 10 inches of rain on eastern Pennsylvania, most of it in a little over six hours. The Wissahickon reached 17.74 feet at Fort Washington, and the Schuylkill at Norristown set a record. The lessons are insurance, speed and preparation.
Key takeaways
- Ida's remnants brought roughly 5 to 10 inches of rain to eastern and south-central Pennsylvania on September 1, 2021, most of it in a little over six hours, according to the U.S. Geological Survey.
- The Schuylkill River at Norristown and the Perkiomen Creek at Graterford reached record levels early on September 2, and the Wissahickon Creek at Fort Washington State Park reached 17.74 feet.
- Standard homeowners policies exclude flood, and a separate flood policy from the National Flood Insurance Program or a private insurer generally takes 30 days to take effect, so it has to be in place before a storm.
- Months after the water went down, 537 people in Montgomery and Chester counties were still living in hotels, according to the Philadelphia Inquirer, a reminder that flood recovery is measured in months.
- The sources used for this guide say little about Ida on the Tookany and Pennypack creeks, so this guide does not put numbers on them, and it says plainly where the record stops.
What happened in Montgomery County on September 1 and 2, 2021?
The remnants of Hurricane Ida crossed eastern Pennsylvania on September 1, 2021, bringing roughly 5 to 10 inches of rain, most of it in a little over six hours, according to the U.S. Geological Survey. Rivers and creeks rose fast overnight, and several set records early on September 2.
By the time Ida reached this area it was a remnant system, and it moved through quickly. The USGS reported that the Schuylkill River at Norristown and the Perkiomen Creek at Graterford reached record levels early on September 2. The agency photographed flooding at a railroad yard in Pennsylvania during the storm.
Local reporting from the Philadelphia area confirmed that seven tornadoes touched down in the region, and officials confirmed three deaths in Montgomery County. This guide keeps to those totals. The human cost belongs to the families, and it is not a teaching example.
In Upper Providence Township, nearly 200 homes were flooded, according to the Inquirer. That is one township, and it is the one figure in the sourced record that counts homes in Montgomery County. There is no sourced county-wide count in the material this guide used.
What does the Wissahickon gauge at Fort Washington tell you?
The USGS gauge at Fort Washington State Park is the local yardstick for the Wissahickon Creek. The creek tends to leave its banks near 12 feet, roads start to flood near 12.9 feet, and on September 1, 2021, it reached 17.74 feet, nearly six feet above the point where it leaves its banks.
A gauge reading is a height, not a depth in your basement. But it shows how far a storm exceeded what the creek normally holds. Ida put the Wissahickon well beyond the level where roads begin to flood.
Flooding was reported in Ambler, Chestnut Hill, North Wales, Flourtown, Blue Bell, Fort Washington, Spring House and Wyndmoor. Forbidden Drive in the park was flooded, and benches and sections of trail were washed away. These were places named in reports, so the list is a starting point and not a complete map.
Wissahickon Trails keeps a page of live updates on the creek's height, and the USGS publishes the gauge readings. If you live near the creek, learn the two thresholds and watch the number during a storm.
| Reading | What it means | Source |
|---|---|---|
| About 12 feet | The creek tends to leave its banks | Local gauge guidance (Wissahickon Trails) |
| About 12.9 feet | Roads start to flood | Local gauge guidance (Wissahickon Trails) |
| 17.74 feet | The reading on September 1, 2021, during Ida | USGS gauge, as reported locally |
Which creeks flooded, and what is not known?
The sourced record is strongest for the Schuylkill, the Perkiomen and the Wissahickon. It is thin for the Tookany and Pennypack creeks during Ida, so this guide gives no figures for them. It also has no county-wide count of flooded homes, total damage or insured losses, and it does not guess.
The Pennypack is the creek with the most documented flood history in Montgomery County's eastern townships. Regional planning documents record damage in Hatboro, Horsham, Upper Moreland, Lower Moreland and Abington, but those documents are about the watershed's history, not about Ida. The Tookany system matters most for Abington and Cheltenham, and the county's own planning papers say most flood damage in the county has come along it.
Those are histories of flooding, and they are worth knowing. They are not Ida numbers. A homeowner reading about Ida should not assume the Wissahickon figures apply to another creek.
The table below separates what the sources carry from what they do not. If you need a number that is in the right-hand column, ask the township, the county or the USGS directly.
| Topic | What the sources carry | What they do not carry |
|---|---|---|
| Rainfall | Roughly 5 to 10 inches in a little over six hours across eastern and south-central Pennsylvania | A reading for any single street |
| Schuylkill at Norristown | Record level early on September 2 | A depth at any particular address |
| Wissahickon at Fort Washington | 17.74 feet on September 1 | The number of homes flooded along the creek |
| Upper Providence Township | Nearly 200 homes flooded | Counts for other townships |
| Tookany and Pennypack creeks | General flood histories | Measured Ida levels or damage totals |
| Insurance | Standard policies exclude flood | How many flooded homes were insured |
Why is flood insurance a separate policy, and when does it start?
Surface water and overflowing creeks and rivers are not covered by a standard homeowners or renters policy. Flood coverage is a separate policy from the National Flood Insurance Program or a private insurer, and it generally takes 30 days to become effective, so it cannot be bought on the day a storm is forecast.
The Pennsylvania Insurance Department publishes guidance on this, and its flood task force has presented on it. The core message is consistent: flood is not a standard homeowners-policy loss. A burst pipe or a sudden leak is a different category, and a sewer or drain backup is typically covered only with an endorsement.
The Pennypack watershed shows what that gap can look like. Regional documents put flood damage across that watershed at $7 million to $10 million, and they note that the real figure could be about five times higher because many homes along the creek carry no flood insurance.
Nothing in this guide is a promise about any claim, because your insurer and your policy wording decide that. Ask your agent three plain questions: Do I have flood coverage? When did it start? Does my policy cover sewer backup? The homeowners insurance guide walks through each category.
What did the recovery show about speed and cleanup?
Recovery took far longer than the storm. By late October 2021, 537 people in Montgomery and Chester counties were still living in hotels. For a flooded house, the practical lessons are that creek water is Category 3, wet porous materials come out, and drying should start within 24 to 48 hours to limit mold.
Creek and river water is Category 3. It carries silt, sewage from overloaded lines and whatever the current picked up, so carpet, pad, wet insulation and low drywall are usually removed instead of dried. Hard surfaces are cleaned and disinfected. The flood damage cleanup page covers the steps in order.
Mold needs a head start, and the EPA's guidance is to dry water-damaged areas and items within 24 to 48 hours. After a regional flood, crews are stretched thin, so help can take time. Documenting the damage with photographs before anything is moved is something you can do while you wait.
Older houses add another layer. Homes built before the 1980s can have asbestos in plaster, joint compound, pipe wrap and old floor tile, and homes built before 1978 fall under the federal lead-safe work rule. Flood cuts disturb those materials, so check with your local authority before demolition.
Moisture lingers in old stone cellars and plaster over lath, so a house can look dry before it is. A technician's readings, not appearance, decide when drying is done.
How should you prepare before the next tropical remnant?
Know your flood coverage and when it started, learn your local gauge, move valuables off the basement floor and test the sump pump. Tropical remnants arrive mostly in August and September, and hurricane season runs June 1 to November 30. Photograph your belongings now, so you have a record before anything is damaged.
Preparation is mostly paperwork and small habits, and it is cheap compared with the damage. The Philadelphia area's recent tropical history includes Floyd in 1999, Isaias in 2020 and Ida in 2021, all in late summer.
Work through the list below once a year, ideally in June, and again if you have moved or changed insurers. Each item is something a homeowner can do without a contractor.
- Check your policy for flood coverage and a water backup endorsement, and note when each started.
- Find the nearest gauge for your creek and learn its flood thresholds. For the Wissahickon that is the Fort Washington State Park gauge.
- Test the sump pump by pouring water into the pit, and ask a licensed plumber about a battery backup.
- Keep gutters, downspouts and window wells clear, and point downspouts away from the foundation.
- Move valuables, documents and electronics off the floor in a basement or ground-floor room.
- Photograph the rooms and major belongings, and keep copies somewhere other than the house.
- Know where the main water shut-off and the electrical panel are, and never wade into floodwater near outlets.
What changed on the Wissahickon after Ida?
In 2025, Montgomery County launched a $1 million, state-backed restoration of an 11-acre floodplain on the Wissahickon Creek in Whitemarsh Township. The work gives floodwater room to spread in a natural setting. The sources used here do not say it protects any individual house, and it does not remove flood risk.
The project is a sign that the creek's flood history is being treated as a planning problem and not only a cleanup problem. A floodplain that can hold water slows the flow downstream, which is the theory behind restoration.
What it means for one homeowner is less clear. A house built near the creek is still near the creek, and flood coverage is still a separate policy. The restoration is useful background, and it is not a substitute for the steps in the previous section.
After a flood, ask a contractor for a Pennsylvania registration number and a written contract. Disaster areas attract unregistered operators, and the guide to contractor registration lists the questions to ask.
Frequently asked questions
How much rain did Ida bring to Montgomery County?
The USGS reported roughly 5 to 10 inches across eastern and south-central Pennsylvania, most of it in a little over six hours on September 1, 2021. It did not publish a single figure for every township, and totals varied from place to place.
What does the 17.74-foot reading mean?
It is the height the Wissahickon Creek reached at the USGS gauge in Fort Washington State Park during Ida. The creek tends to leave its banks near 12 feet, and roads begin to flood near 12.9 feet. It describes the creek, not your basement.
Is flood damage covered by my homeowners policy?
Standard homeowners policies exclude flood. Flood coverage is a separate policy that generally takes 30 days to become effective. Sewer backup is typically covered only with an endorsement. Your insurer decides coverage, so ask your agent.
Which parts of Montgomery County flooded during Ida?
Reports name Ambler, North Wales, Blue Bell, Spring House, Fort Washington, Flourtown and Wyndmoor on the Wissahickon, and Norristown on the Schuylkill, plus Upper Providence Township. These are places named in reports, not a complete map. Check your own address.
How soon should drying start after a flood?
The EPA's guidance is a window of 24 to 48 hours. Creek water is Category 3, so porous materials usually come out. Call (833) 490-5225 to describe the damage, and a crew is dispatched as fast as one is available.
Sources
- U.S. Geological Survey: Hurricane Ida, USGS response in Pennsylvania, September 1-2, 2021
- Wissahickon Trails: Live updates on the height of the Wissahickon Creek
- Philadelphia Inquirer: Ida flooding in the Philadelphia area leaves residents still without homes (October 22, 2021)
- Pennsylvania Insurance Department
This guide is general information for Montgomery County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.