--- title: three waters reach philadelphia canonical_url: https://ensurance.app/guide/three-waters-reach-philadelphia markdown_url: https://ensurance.app/guide/three-waters-reach-philadelphia.md subtitle: "ida on the schuylkill, a wet-weather sewer, and a later tide at eastwick" category: ecosystem-services --- # three waters reach philadelphia *ida on the schuylkill, a wet-weather sewer, and a later tide at eastwick* On 1 September 2021 the Schuylkill came up into Philadelphia. The city, writing the next day, called it historic flooding on the Schuylkill and on other city waterways, and put the infrastructure and personnel cost at over $31 million at that moment. That night is one water. A typical wet year in the combined sewers is a second water. The tide that can pond in Eastwick on a dry day, by a path a Cobbs Creek levee does not close, is a third. They reach the same city. They are not the same storm. Philadelphia is the door. The living system is the fall line where those waters meet: the Schuylkill off the piedmont, the tidal Delaware, and Cobbs and Darby at Eastwick. The meeting exists whether or not anyone buys a certificate. :::johnson **three waters reach this city. keep their dates on them.** Ida is a river flood with two public counts that disagree. The sewer is a typical-year volume from a July 2023 letter. Eastwick's tide is a later path. ::: ## the schuylkill, september 2021 The early city page is a snapshot taken while the water was still the news. Over $31 million, infrastructure and personnel, "at this moment." It is an early estimate. It is not a final loss, and these notes do not treat it as a carrier's Philadelphia book. Insurers were not assessed that way. FEMA's preliminary damage assessment for the Pennsylvania declaration, with Philadelphia as an Individual Assistance county, lists a Philadelphia block: 1,200 residences impacted, 81 destroyed, 554 with major damage, 439 minor, 126 affected, and 33 percent of residences with flood insurance. That is the PDA for DR-4618. The Inquirer, on 10 August 2023, read a later city report. The figures in that reading are different, and they stay different. 11,000 residences with FEMA-verified losses. 81 destroyed. 500 major. Rain of 3.97 to 5.69 inches in 12 hours. The Schuylkill at 16.35 feet. Pennypack Creek at 14.57 feet. 1,100 residents evacuated. 29 boat rescues. 1,200 residences flooded. 22 percent of Manayunk commercial spaces with severe damage. City businesses at $12 million in listed losses. HUD at $163 million. Unmet needs at $1.2 billion. Heavy damage on the Schuylkill River Trail, the Pennypack Park Trail, and in Wissahickon Valley Park. The 81 destroyed matches the PDA. The residence totals do not: 1,200 in the early block, 11,000 verified losses in the later reading, and 500 major beside the PDA's 554. Both documents are cited because both exist. Adding them would invent a third disaster. The $163 million and the $1.2 billion are the Inquirer's reading of relief and unmet need. They are not a premium for the river. If you were in Manayunk that week, the commercial street is the fact you already have. If you use the Schuylkill River Trail, the trail is on the damage list. The piedmont park on the Wissahickon is on it too. The dependence runs back to the river: a trail, a main street, and a park gorge are how this city touches the Schuylkill, and the Schuylkill touched them back in twelve hours of rain. ## the sewer in a wet year Combined-sewer overflow is what leaves the system when rain or snowmelt exceeds the interceptors. The water department's letter of 20 July 2023 puts a typical year, at the start of Green City, Clean Waters in 2011, at 13 billion gallons. By the 2021 regulatory report the volume was down 3.08 billion gallons in a typical year, against a required reduction of 2.044 billion. About five billion gallons a year of further reduction remained. The letter says dry-weather sanitary discharges of the kind some cities fight are not the known condition here, and that dry-weather combined-sewer discharges are infrequent. The remaining problem is wet weather. That volume is not Ida's crest. Ida is a date, a stage on the Schuylkill, a count of houses. The five billion gallons are a typical-year target still ahead as of that letter, benchmarked to the 2021 report. The fiscal-year 2024 overflow volume was not extracted from the permit file for these notes. The share of the city on combined sewers was not taken from a department page. Both stay out. The program that counts those gallons, and the reason this series does not put a price on them, is [who already works the philadelphia gallons](/guide/who-already-works-the-philadelphia-gallons?from=guide). The intakes that drink the same rivers the sewers can discharge to are [philadelphia drinks two rivers](/guide/what-philadelphia-stands-on?from=guide). ## the tide at eastwick, which is later Eastwick floods now from Darby and Cobbs. It also floods when the Delaware and the Schuylkill rise and the water comes up through Darby Creek. The Office of Sustainability said so on 12 October 2023. Sea-level rise can put water on the ground on a dry day. The Cobbs Creek levee, an Army Corps draft of about 1,400 feet from August 2023, is a riverine project. It needs a sponsor. It does not close the tidal paths. The city memo's later case is four feet of sea-level rise, as soon as the 2080s, with chronic tidal flooding as widespread as today's extreme rain. The paths it names are the Darby Creek estuary in the John Heinz refuge, and Mingo Creek. A 2023 modeling paper, a HEC-RAS study rather than an ordinance, finds high-tide flooding possible as soon as the 2060s, and at 1.2 meters of sea-level rise a flooded share of 34.4 percent of Eastwick, above Tropical Cyclone Isaias in 2020 at 30.7 percent. Print the paper as the paper. The city has not adopted that percentage as a rule. The airport sits on this edge. These notes have no climate-loss figure for it. The port's channel is the same Delaware, used as depth. Its 2024 volumes are in [who depends on the rivers at philadelphia](/guide/who-depends-on-the-rivers-at-philadelphia?from=guide). The creeks as a living edge, rather than as a damage table, are in [the schuylkill meets a tide](/guide/the-schuylkill-meets-a-tide?from=guide). The Global Covenant of Mayors profile marks flood and sea level rise as high, on a short-term timescale, river flood as medium high and short-term, and coastal flood as medium low on a medium-term timescale. The profile's mayor field was stale when these notes were taken. The hazard rows are still the rows on the page. ## what you can do with the dates If you work for the city, a floodplain office, or a watershed partnership and you need the public door for that reading, it is [governments](/solutions/governments?from=guide&topic=philadelphia-fall-line). This series does not price Philadelphia flooding. It does not turn the HUD figure or the unmet-needs figure into a premium. River flood, as a shared account, is [flood resilience](/flood-resilience.syndicate?from=guide). The estuary tide is [coastal resilience](/coastal-resilience.syndicate?from=guide). If you hold a loss figure these notes do not have, for a terminal, a carrier book, or the airport, [send it with this series in the subject](/contact?from=guide&topic=philadelphia-fall-line). The figure would be news. It would still need a unit before anyone could call it an offer, and this page does not supply that unit. ## frequently asked questions ### did hurricane ida flood philadelphia? Yes. On 1–2 September 2021 the Schuylkill and other city waterways flooded. The city put infrastructure and personnel damage at over $31 million the next day, as an early estimate. FEMA's preliminary assessment lists 1,200 residences impacted and 81 destroyed in the Philadelphia block. A 2023 Inquirer reading of a later city report lists 11,000 FEMA-verified residential losses. Use both. Do not add them. ### how high did the schuylkill get? The Inquirer's 10 August 2023 reading gives 16.35 feet on the Schuylkill and 14.57 feet on Pennypack Creek, with 3.97 to 5.69 inches of rain in 12 hours. Wissahickon Valley Park is on that damage list. ### is a combined sewer the same as that flood? No. The sewer figure in these notes is a typical year: 13 billion gallons at the start of the program in 2011, about 5 billion a year still to cut as of the department's July 2023 letter. Ida is a storm date and a river stage. Eastwick's tide is a later rise that can arrive through Darby Creek even when the Schuylkill is the story people remember. ### who already pays for the sewer overflow? Ratepayers, through the water department's Green City, Clean Waters program. The count and the cost conflict are on the next page of this series. These notes do not add a second price. ## sources [City of Philadelphia, 2 September 2021](https://www.phila.gov/2021-09-02-city-responds-to-damage-and-flooding-from-storm-ida/) — the early infrastructure estimate. [FEMA preliminary damage assessment, DR-4618](https://www.fema.gov/sites/default/files/documents/PDAReport_FEMA4618DR-PA.pdf) — the Philadelphia residence block. [The Philadelphia Inquirer, 10 August 2023](https://www.inquirer.com/science/climate/hurricane-ida-philadelphia-block-grant-hud-20230810.html) — the later city-report reading. Kept separate from the PDA. [Philadelphia Water Department, 20 July 2023](https://water.phila.gov/drops/pwd-response-to-penn-environment-sewage-statement-july-20/) — typical-year overflow gallons. [City of Philadelphia, 12 October 2023](https://www.phila.gov/2023-10-12-city-releases-rfp-for-eastwick-flood-resilience-strategy/) — Eastwick's two flood paths. [Eastwick technical memo](https://www.phila.gov/media/20230914092305/Eastwick-Flood-Mitigation-Measures-technical-memo.pdf) — four feet, the 2080s, Heinz, and Mingo. [U.S. Army Corps of Engineers, Eastwick study](https://www.nap.usace.army.mil/Missions/Civil-Works/Eastwick-Flood-Risk-Management-Study/) — the levee draft. [Water 2023, HEC-RAS study of Eastwick](https://www.mdpi.com/2073-4441/15/14/2671) — a simulation, not an ordinance. [Global Covenant of Mayors, Philadelphia](https://www.globalcovenantofmayors.org/cities/usa/united-states/philadelphia-pa/) — hazard rows. ## the series - [philadelphia drinks two rivers](/guide/what-philadelphia-stands-on?from=guide) - [who depends on the rivers at philadelphia](/guide/who-depends-on-the-rivers-at-philadelphia?from=guide) - [the schuylkill meets a tide](/guide/the-schuylkill-meets-a-tide?from=guide) - [three waters reach philadelphia](/guide/three-waters-reach-philadelphia?from=guide) - [who already works the philadelphia gallons](/guide/who-already-works-the-philadelphia-gallons?from=guide)