Rooster River Flood Mitigation Assessment

Rooster River is a significant hydrologic feature which runs between the City of Bridgeport (City) and the Town of Fairfield. The watershed to Rooster River is 15.3 square miles, and tributaries include Londons Brook, Horse Tavern Brook, and Ox Brook. The river flows into the tidal Ash Creek, and ultimately to Long Island Sound. Its watershed has been highly urbanized, with approximately 94% of the watershed classified as developed land (as mapped for 2021 by the National Land Cover Database [NLCD]) and 34% of the overall watershed covered by impervious surfaces (as mapped by Connecticut Environmental Conditions Online [CTECO] in 2012). The stream channels and their tributaries have, in many locations, been altered, channelized, concrete-lined, or diverted to underground stormwater drainage systems. For decades the City has experienced challenges with flooding along the Rooster River.

This project seeks to identify locations within the City that are prone to persistent flooding, susceptible to damage from significant rainfall events, or likely to encounter new challenges as climate patterns and watershed dynamics shift over time. To address these concerns, the project will evaluate both structural and non-structural flood mitigation strategies through a series of key tasks: comprehensive data collection and review, hydrologic and hydraulic (H&H) analysis, development and assessment of mitigation alternatives with order-of-magnitude cost estimates, preparation of conceptual analysis reports, and ensuring compliance with the Connecticut Environmental Policy Act (CEPA).

This project modeled flooding within the watershed during normal rain events, extreme rain events, and future rain events with two primary objectives. First, it aimed to assess the vulnerability of facilities, infrastructure, and urban development along the Rooster River and its tributaries within the study area. Second, it focused on developing a suite of H&H models to evaluate the extent of potential flooding across various storm recurrence intervals. These models and supporting data informed the identification and evaluation of design measures intended to reduce both current and anticipated flood risks. Where feasible, the proposed solutions emphasized nature-based strategies that enhance or replicate the watershed’s inherent flood protection functions, such as floodplain reconnection and wetland restoration—commonly referred to as “green infrastructure.” Unlike structural interventions, these approaches also offer co-benefits including improved water quality, enhanced aesthetics, recreational opportunities, and wildlife habitat. Due to the highly urbanized nature of the City’s watershed, in addition to nature-based approaches, the project also considered more intensive engineering solutions, including floodwalls, berms, channel bypasses, and bridge replacements, to ensure adequate flood protection.