Ohio Sediment Reference Values (SRVs)

Overview

Ohio EPA’s Sediment Reference Values (SRVs) are screening concentrations for metals in stream sediment, developed from sampling at biological reference sites across Ohio’s five Level III ecoregions. SRVs represent background concentrations at locations least impacted by contaminant releases.

SRVs are published in Attachment H of the Ecological Risk Assessment Guidance Document (DERR-00-RR-031, July 2018). Under OAC 3745-300-08(I)(2), SRVs are the first-tier screening tool for evaluating sediment contamination at VAP sites with lotic (flowing) water bodies.

SRVs are not toxicity-based values. They identify whether metal concentrations in site sediment exceed what would be expected at a clean reference site in the same ecoregion. If SRVs are exceeded, additional screening against consensus-based sediment quality guidelines (TECs and PECs) is the next step in the ecological risk assessment process.

Ohio Ecoregions

SRVs vary by ecoregion because natural background metal concentrations differ based on underlying geology, soil type, and land use patterns. Ohio has five Level III ecoregions used for SRV classification:

ECBP - Eastern Corn Belt Plains: Covers much of western Ohio. Flat to gently rolling terrain, glacial till soils, predominantly agricultural land use. Underlain by Ordovician and Silurian limestone and shale.

EOLP - Erie Ontario Lake Plain: Northern Ohio along the Lake Erie shore. Lake plain sediments, clay-rich soils. Includes the Toledo and Sandusky areas.

HELP - Huron Erie Lake Plain: Northwest and north-central Ohio. Similar to EOLP but extends further south. Flat terrain, clay soils, agricultural land use.

IP - Interior Plateau: South-central Ohio. Unglaciated terrain with more rugged topography. Underlain by Devonian and Mississippian limestone and shale.

WAP - Western Allegheny Plateau: Eastern Ohio. Unglaciated, hilly terrain. Underlain by Pennsylvanian sandstone, shale, and coal. Coal mining history influences background metal concentrations in this region.

Some metals only have statewide SRVs rather than ecoregion-specific values. This occurs when insufficient reference site data was available for individual ecoregions.

Sediment Reference Values - All Metals

All values are in mg/kg (dry weight). “N/A” indicates no value was established for that ecoregion.

Notes:

• Values are from Table 2 of the Ohio EPA DERR Ecological Risk Assessment Guidance, July 2018.
• Silver value footnote: “Value for silver was derived as indicated, however a judgment regarding the validity of the maximum concentration should be made.”
• “N/A” in the source document indicates the parameter was analyzed but no reference value was established for that ecoregion. A dash (-) indicates no data was reported.

How SRVs Are Used

SRVs are the first step in a tiered screening approach for sediment at VAP sites:

Step 1 - Compare to SRVs: If all metal concentrations in site sediment are below the applicable ecoregion SRV (or statewide SRV), sediment contamination is unlikely and no further ecological evaluation of sediment may be needed.

Step 2 - Compare to TECs: If any metal exceeds its SRV, compare to the consensus-based Threshold Effect Concentration (TEC) from MacDonald et al. (2000). Concentrations below the TEC are unlikely to cause adverse effects to sediment-dwelling organisms.

Step 3 - Compare to PECs: If any metal exceeds its TEC, compare to the Probable Effect Concentration (PEC). Concentrations above the PEC are likely to cause adverse effects and typically require further evaluation or remediation.

Step 4 - Additional assessment: If PECs are exceeded, additional ecological risk assessment (toxicity testing, bioaccumulation analysis, or a full Level II/III ecological risk assessment) may be warranted depending on site conditions.

The consensus-based TECs and PECs referenced above are from: MacDonald, D.D., C.G. Ingersoll, and T.A. Berger. 2000. “Development and Evaluation of Consensus-Based Sediment Quality Guidelines for Freshwater Ecosystems.” Archives of Environmental Contamination and Toxicology 39:20-31.

Practical Notes

• Determine your ecoregion first. Using the wrong ecoregion’s SRV can lead to incorrect screening conclusions. Ohio EPA’s ecoregion boundaries can be found on the Ohio Geology Interactive Map or in the ecological risk assessment guidance document.

• SRVs are for metals only. Organic contaminants in sediment (PAHs, PCBs, pesticides) are screened against TECs, PECs, and EPA Region 5 Ecological Screening Levels (ESLs) - not SRVs. The ecological risk assessment guidance provides the full hierarchy.

• SRVs apply to lotic (flowing) water bodies. They were developed from stream and river reference sites. For lentic (still water) environments like lakes and ponds, different screening approaches may be needed.

• Dry weight basis. All SRVs are reported on a dry weight basis. Make sure your laboratory reports sediment chemistry on a dry weight basis for direct comparison.

• Natural variability. Some metals - particularly manganese, iron, and aluminum - have wide natural ranges depending on local geology. Exceedance of an SRV for these metals does not necessarily indicate anthropogenic contamination. Consider the geologic setting.

Related Resources

• Ohio VAP Program Overview - How sediment screening fits into the broader VAP process
• Ohio EPA Ecological Risk Assessment Guidance (PDF) - Full guidance document with SRV tables in Attachment H
• NOAA CAFE Database - Chemical fate and aquatic toxicity data (replaced the retired SQuiRT cards)
• Ohio EPA Fish Advisory Map - Fish consumption advisories for Ohio waterways