Iowa’s Impaired Waters: A Growing Concern and Delayed Action

Iowa’s waterways are facing increasing challenges with pollution, leading to a growing list of “impaired waters” that don’t meet state and federal water quality standards. Despite legal requirements for addressing these issues, progress has been slow, raising concerns about the long-term health of Iowa’s aquatic ecosystems and the potential impact on human health. This article examines the state of Iowa’s impaired waters, the process for addressing pollution, and the obstacles hindering effective solutions.

What are Impaired Waters?

Every two years, the Iowa Department of Natural Resources (DNR) creates a list of impaired waters, also known as a 303(d) list, as mandated by the Clean Water Act. This list identifies water bodies that are not meeting their designated water quality standards. Once a water body is placed on the list, the DNR is legally obligated to prepare a Total Maximum Daily Load (TMDL) – a plan outlining how much pollution can be discharged into the water while still meeting those standards, and a roadmap for achieving compliance.

Key Pollutants and Recent Listings

Several pollutants contribute to Iowa’s impaired waters. Nitrate and nitrite pollution, largely stemming from agricultural runoff of manure and commercial fertilizer, have led to the listing of major rivers like the Cedar River, Des Moines River, Iowa River, Raccoon River, and South Skunk River. Fecal indicator bacteria are another significant concern, potentially impacting human and animal health.

The TMDL Process and Current Delays

The 2026 draft of impaired waters reveals a concerning trend: many water segments have been on the list since 2006 and 2008, yet a TMDL has not been prepared for them. This delay undermines the purpose of the 303(d) list and the Clean Water Act. Some of these long-standing impaired waters are even designated as “Outstanding Iowa Waters,” which are entitled to extra protection under the state’s antidegradation policy. Despite this designation, the DNR has often assigned them low priority (Tier III and Tier IV) for TMDL development, effectively delaying any meaningful action.

Legislative Challenges and Concerns

Recent legislative proposals have raised further concerns about the state’s commitment to addressing water quality. A bill considered by the legislature would require the DNR to identify the specific animal species contributing to fecal bacteria contamination before listing a water body as impaired. Critics argue this requirement is unnecessary and serves as a tactic to avoid listing waters as impaired, delaying necessary cleanup efforts.

The Role of Agriculture

Agricultural practices are a major contributor to water pollution in Iowa. Since 95% of Iowa’s land is farmed, runoff from manure and commercial fertilizer is a primary source of nitrate and nitrite contamination. When plants don’t absorb all applied fertilizer and manure, rain and snowmelt carry excess nutrients into rivers, streams, and lakes.

Looking Ahead

The situation with Iowa’s impaired waters demands greater attention and more decisive action. Ensuring the DNR prioritizes TMDL development for all impaired waters, particularly those designated as Outstanding Iowa Waters, is crucial. Addressing agricultural runoff through improved farming practices and responsible fertilizer management is also essential for restoring and protecting Iowa’s valuable water resources. Without a stronger commitment to implementing the Clean Water Act and addressing pollution sources, the health of Iowa’s waterways – and the communities that depend on them – will continue to be at risk.