Jump to main content or area navigation.

Contact Us

CADDIS Volume 2: Sources, Stressors & Responses

energy sources physical habitat hydrology temperature water and sediment quality stormwater runoff wastewater inputs riparian and channel alteration urbanization

What are wastewater inputs?

Urbanization often involves the input of wastewaters into streams and rivers. Common wastewater sources in urban streams include:

Wastewater treatment plant (WWTP) effluents: permitted municipal sewage discharges (Fig 10), treated to varying degrees (see Table 3)

Industrial effluents: permitted discharges from industrial facilities

Accidental or unpermitted discharges

Sanitary sewer overflows: wet weather overflows resulting in direct discharge of domestic and other wastewaters into streams and rivers

Combined sewer overflows (CSOs): wet weather overflows resulting in direct discharge of surface runoff and domestic and other wastewaters into streams and rivers

Sewer pipes: leakage from broken, blocked or aging infrastructure

Septic systems: leachate from septic tanks (usually in less densely developed areas)

Stressors associated with wastewater inputs

Numerous stressors may be associated with wastewater inputs, including:

Click below for more information on specific topics

combined sewer overflow button waterwater-related enrichment button reproductive effects of wwtp effluents button
Figure 10. Historical and projected US resident population served by publicly-owned wastewater treatment facilities, and the volume of wastewater flows produced.
Adapted from U.S. EPA. 2000. Progress in Water Quality: An Evaluation of the National Investment in Municipal Wastewater Treatment. U.S. Environmental Protection Agency, Office of Water, Washington DC. EPA-832-R-00-008.
WWTP discharge on Fourmile Creek, IA.
Courtesy of USGS.
Table 3. Typical treatment efficiencies of municipal sewage treatment for specific pollutants
Typical Treatment Efficiencies
(% inflow concentrations)
Sewage Ponds
Secondary treatment
Advanced Treatment
BOD* 50-95 95 95
Nitrogen 43–80 50 87
Phosphorus 50 51 85
Suspended solids 85 95 95
Metals Variable Variable Variable
*BOD = biological oxygen demand.
Modified from Baker LA. 2009. New concepts for managing urban pollution. Pp. 69-91 in: Baker LA (ed). The Water Environment of Cities. Springer Science+Business Media, LLC.

Jump to main content.