Nutrient Assessment and Reduction Plans
Wastewater treatment facilities in our watersheds operate under NPDES (National Pollution Discharge Elimination System) Permits that are issued by the Illinois Environmental Protection Agency (EPA). These permits are made up of a number of Special Conditions that dictate how the plant operates and sets limits on what and how much can be discharged from their facility into the local receiving stream.
As a way to address both local and downstream (think: Gulf of Mexico dead zone) impacts of excess nutrients, namely phosphorus and nitrogen, the Illinois EPA has included a special condition in the NPDES permits that requires the development of a Nutrient Assessment and Reduction Plan or NARP by the end of 2023. This requirement is placed in permits that discharge to stream segments that are impaired or are at risk of impairment for nutrient related dissolved oxygen or nuisance algae.
Instead of every wastewater agency doing their own NARP, permit holders can work together with other agencies in their watershed to complete a single NARP for the watershed. This is both more cost effective and will result in a more complete assessment and plan for how to address excess nutrients in the watershed.
The NARP will assess both point sources (wastewater or industrial discharges) and nonpoint sources (stormwater runoff) of nutrients, identify what types of practices or projects could be implemented to reduce the source of nutrients and a timeline for implementation. Action items in the plan will be inserted into future wastewater NPDES permits and possibly MS4 stormwater permits by Illinois EPA.
Since every watershed is a little different and each watershed group has different resources or amounts of data, every NARP will be a little different. Some of the common components between the Lower DuPage River and the Lower Des Plaines River will be the use of the IPS Model to potentially set an instream threshold for phosphorus and utilizing a Nonpoint Source Feasibility study to look at the impacts of leaf litter in roadways and the reductions gained through street sweeping and leaf collection practices.
As these plans are still under development, we will be updating the NARP pages specific to each watershed group as more information becomes available.
Learn more what you can do to help manage nutrients as a resident.