Many small cities across Northwest Iowa have chloride requirements written directly into their Iowa NPDES permits — and they don’t know it. If your community hasn’t reviewed its permit recently, now is the time. Waiting until the next renewal cycle can significantly limit your options and drive up costs.
At a recent Northwest Iowa League of Cities meeting, BEI’s Zach Arneson and Joe Anderson joined Iowa DNR Environmental Specialist Tom Roos to break down what chloride compliance means for small communities — and what cities should be doing today to get ahead of it.
What Is Chloride, and Why Does It Matter?
Chloride is a dissolved salt that enters wastewater systems through several common sources:
- Water softeners (one of the most significant contributors in residential areas)
- Road salt and winter deicing chemicals
- Industrial discharge
- Drinking water treatment processes
Unlike many contaminants, chloride does not naturally break down. It accumulates in receiving streams over time, where high concentrations can harm aquatic life, damage vegetation, and degrade water quality. Because of this, the Iowa DNR regulates chloride through NPDES permits, with discharge limits based on receiving stream conditions and flow characteristics.
Permits are typically renewed every five years and include both average and daily discharge limits. Chloride limits have been included in Iowa NPDES permits since 2009 — but many communities are only now receiving formal compliance schedules.
What Happens When a Community Receives a Compliance Schedule?
A compliance schedule outlines the steps and deadlines your community must meet to achieve permitted limits, which typically include:
- Wastewater sampling to establish baseline chloride levels
- Chloride reduction studies to identify the major sources in your system
- Water quality and mixing zone evaluations of your receiving stream
- Infrastructure planning and design for treatment or source reduction improvements
- Construction of necessary system improvements
Schedules can span several years, and one critical point from the DNR: chloride compliance cannot be solved at the treatment plant alone. Communities that start early have more flexibility — those that wait face compressed timelines and higher costs.
Strategies for Reducing Chloride
The Iowa DNR Chloride Toolbox outlines proven approaches communities can take, including:
- Water softener upgrades or exchange programs — high-efficiency softeners use significantly less salt
- Industrial source reduction — working with commercial and industrial users to reduce chloride discharge
- Drinking water treatment review — evaluating whether treatment processes are contributing to chloride load
- Site-specific water chemistry testing — to understand your community’s unique profile
- Discharge modifications — adjusting how and where treated water enters receiving streams
The right combination of strategies will depend on your community’s size, permit limits, and primary chloride sources. A chloride reduction study is typically the first step in identifying where to focus.
Funding Options to Know About
Cost is often the first concern for small municipalities — and understandably so. The good news is that chloride compliance projects may be eligible for several funding programs, including:
- Iowa SRF (State Revolving Fund) loans — low-interest financing for wastewater improvements
- CDBG (Community Development Block Grant) — available for communities meeting income thresholds
- Iowa DNR Water Resource Restoration Sponsor Program — for projects with water quality benefits
Early engagement with your compliance schedule gives you more time to pursue these funding sources before construction timelines become urgent.
What Your Community Should Do Right Now
Pull your current Iowa NPDES permit and look for chloride limits or compliance schedule language. Note any deadlines already listed. If you’re unsure what you’re looking at, contact your engineer or the Iowa DNR — and consider beginning a chloride reduction study, which is typically the foundational first step.
How BEI Can Help
BEI works with municipalities across Iowa on wastewater planning, NPDES compliance, infrastructure funding, and utility improvements. We co-presented this material with Iowa DNR at the Northwest Iowa League of Cities because we believe informed communities make better decisions. If your city has questions about chloride limits or where to start, we’re glad to help.