Albany Pool Communities CSO Notification System

Frequently Asked Questions

What are combined sewer overflows (CSOs)?
Combined sewer systems are sewer systems that are designed to collect stormwater runoff, domestic sewage, and industrial wastewater in the same sewer and convey that combined flow to a wastewater treatment facility for treatment prior to discharge to a waterbody.
During wet weather events (e.g., rainfall or snowmelt), when runoff enters the sewers, the capacity of the sewer system may be exceeded and the excess water will be discharged directly to a waterbody. Where the excess water is discharged directly into the waterbodies is called a combined sewer overflow (CSO). Capital District CSOs are discharged directly into the Hudson River and its tributaries.

Are CSOs legal?
CSOs are allowable discharges under the Clean Water Act (CWA) and are regulated as permitted discharge points by the New York State Department of Environmental Conservation (NYS DEC) under a communities’ State Pollution Discharge Elimination System (SPDES) permit. There are almost 750 communities with combined sewer systems, and they are regionally concentrated primarily in older communities in the Northeast and Great Lakes regions.

What is being done to minimize the impacts of CSOs on our waterbodies?
In 1994 the United State Environmental Protection Agency (US EPA) enacted the CSO Control Policy. The Policy contains four fundamental principles to ensure that CSO controls are cost-effective and meet local environmental objectives:

  • 1. Clear levels of control to meet health and environmental objectives.
  • 2. Flexibility to consider the site-specific nature of CSOs and find the most cost-effective way to control them.
  • 3. Phased implementation of CSO controls to accommodate a community's financial capability.
  • 4. Review and revision of water quality standards during the development of CSO control plans to reflect the site-specific wet weather impacts of CSOs.
In 2007, the Cities of Albany, Cohoes, Rensselaer, Troy, and Watervliet and the Village of Green Island (referred to as the Albany Pool Communities) joined in a comprehensive inter-municipal venture, led by the Capital District Regional Planning Commission (CDRPC) to develop a CSO Long Term Control Plan (LTCP) in accordance with the CSO Control Policy. CDRPC is the entity aiding in the implementation of the LTCP and coordination of the communities, acting both as a resource and a facilitator. In January 2014 the Albany Pool Communities entered into an Order on Consent agreement with the NYS DEC requiring improvements in each community to minimize the impacts of CSOs on the Hudson River.
Implementation of the LTCP will ultimately reduce the volume and frequency of CSO discharges into the Hudson River. The improvement projects include:
  • Disinfection at the three wastewater treatment plants.
  • Wastewater Treatment Process Improvements
  • Sewer System Optimization
  • Sewer Separation and Storage
  • Green Infrastructure Program
  • Satellite Treatment and Floatables Control
  • Tributary System Enhancements
Implementation of these improvements, representing an over $130 million investment over 15 years, will provide new opportunities for communities to showcase our greatest asset – a river so captivatingly attractive it spawned an arts movement and inspired the modern environmental movement.
CDRPC is a regional planning and resource center serving Albany, Rensselaer, Saratoga, and Schenectady Counties. CDRPC serves the best interests of the public and private sectors by promoting intergovernmental cooperation; communicating, collaborating, and facilitating regional initiatives; and sharing information and fostering dialogues on solutions to regional problems.

How do CSOs impact the Hudson River?
The Albany Pool Communities conducted extensive sampling of the Hudson River and developed a water quality model of the river to determine how fecal bacteria from CSOs impact it. The evaluations completed to develop the LTCP included a five year assessment of these impacts. The potential impact of CSO discharges on this reach of the Hudson River is greatest during the recreational period(between May and October) which the likelihood of primary and secondary contact through swimming and fishing is the greatest. Currently, during average rainfall conditions, there are 30 exceedances of the bacterial(geomean) of the River. The geomean is quantitative approach to understanding the overall water quality. It does not indicate that the bacteria levels will be below the 200 cfu/ml requirement at all locations, but the overall body of water will meet that requirement. After the LTCP is completed, the water quality model predicts that there will be no exceedances of the bacterial geomean during the typical 5 year period modeled.
Since the Albany Pool Communities cannot guarantee all locations will meet the bacteria water quality standard, the notification system has been developed to provide individuals with an understanding of the likelihood of CSOs in a given location based on rainfall. It is recommended during these periods that the public remain out of contact with the Hudson River.

Why do different CSO discharge points on the map show different likelihoods of discharge for the same rain fall event?
Rainfall patterns can vary widely across a system as geographically diverse as the Albany region. In summertime in particular, it is not uncommon for one area to receive significant rainfall while an adjacent area is sunny and dry. Therefore, one can expect to see a CSO discharge in Albany, for example, while Cohoes CSOs are not discharging.
Further complicating matters, each CSO and its tributary area (the area upstream from which wastewater and stormwater is conveyed to the CSO) reacts differently to rainfall. The nature of the tributary area—its impervious surface coverage, amount of green space and tree canopy, amount of building and other surfaces that are directly connected to the sewer system, and overall size—determines its response to a given rainfall. Some systems respond immediately to any rainfall amount while other systems take more rainfall for runoff (and therefor for a CSO discharge) to occur.
For this public notification system, the probability of CSO discharge is based on results from a detailed mathematical model of the combined sewer systems in each community that was calibrated to in-system flow monitoring data. These results provided predicted CSO discharge events for a five-year period. Using each of these events and the associated rainfall total, an analysis was completed to determine for each CSO a rainfall threshold (minimum amount of rainfall) required for a CSO discharges to be predicted by the model. This rainfall threshold is unique to each CSO and therefore viewers will see different CSO discharge points on the map with different probabilities of discharge for the same rainfall event.