Aerial image of the District of Columbia in the background with a presentation title overlayed on top that says, "Re-Evaluating Toxics Impairments in the District of Columbia, Jonathan Champion, DOEE and Tim Schmitt, LimnoTech. Presented at AWRA National Capital Region Water Resources Symposium, April 12, 2024. Logos for DOEE and LimnoTech are at the bottom.

Tim Schmitt Talks Toxic Impairments at the 2024 AWRA National Capital Region Water Resources Symposium

April 17, 2024

Tim Schmitt, Principal and Senior Environmental Scientist at LimnoTech, participated in the 2024 National Capital Region Water Resources Symposium on April 12 at the University of the District of Columbia in Washington, DC. The symposium was held by the American Water Resources Association (AWRA) National Capital Region Section (NCRS). The AWRA-NCRS chapter brings together professionals working on water resources issues in the National Capital Region, which covers the District of Columbia and parts of Maryland, Virginia, and West Virginia.

The AWRA-NCRS’ describes this one-day symposium as an opportunity to gather experts from “governmental agencies, academia, the private sector, and nonprofits to discuss challenges and opportunities for sustainable management of water resources and infrastructure in the region, as well as nationally and internationally.” The theme for this year’s symposium was “Federal Funding Access for Emerging Water Resources and Water Infrastructure Challenges,” and covered topics such as emerging smart technologies and data management systems; climate change and water resources; watershed science, groundwater studies, water ecosystems, and stormwater management; emerging contaminants in water; and social justice and equity in water management.

Tim and Jonathan Champion, Associate Director of the Water Quality Division (WQD) at the Department of Energy and Environment (DOEE), co-presented on “Re-Evaluating Toxics Impairments in the District of Columbia” during the session on “Advances in Water Quality Management.”

The abstract below provides a summary of the presentation:

“The District of Columbia is unusual in that it has impairments attributed to toxics such metals and organic pesticides in many of its waterbodies. As part of our [LimnoTech’s] support to the District Department of Energy and Environment [DOEE], we investigated these toxic impairments to ensure that they were supported by water quality data. One of the problems we encountered was that much of the data we were using was reported as below detection limits of the analytical equipment, and thus did not produce a number that could be compared against a criterion to determine exceedance (and thus, impairment).

To address this, we developed a methodology that evaluated the ratio of the detection limit for a given toxic to the criterion for that toxic. If the ratio was below 1, then the detection limit was lower than the criterion, and data could be used directly to evaluate impairment. However, if the ratio was above 1, then the criteria were below the detection limit, and non-detect results had to be treated differently to determine impairment. This presentation will explain the methodology and describe how it was used to confirm or not confirm the existence of toxic impairments in the District.”

You can view the full presentation here.

Tim thought this conference was a great opportunity to share some of the problems the District is facing and opportunities for innovative solutions with a local audience that lives and works in the waterways he was describing. Many symposium attendees are also doing work on the water quality of District waters, so this topic really resonated with the audience.

If you have questions or want more information, you can reach out to Tim Schmitt at

You can also check out LimnoTech’s work in Permits and Standards, Urban Wet Weather, and Water Resource Investigation and Management.

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