UPDATE: Lower Susquehanna Source Water Protection Partnership

Lower Susquehanna Source Water Protection Partnership

You are receiving this email because you registered for the December 2021 Lower Susquehanna Source Water Protection Partnership meeting or are on our Partnership email distribution list. The Partnership’s Steering Committee wants you to be informed about the Pennsylvania Environmental Quality Board’s proposal to establish drinking water Maximum Contaminant Levels for two per- and polyfluoroalkyl substances (PFAS).


Public comments will be accepted until Wednesday April 27, 2022.  The Pennsylvania Bulletin document no. 22-313 (https://www.pacodeandbulletin.gov/Display/pabull?file=/secure/pabulletin/data/vol52/52-9/313.html) has the complete PFAS Maximum Contaminant Levels proposal narrative, names of persons to contact for additional information, the schedule for public hearings, (note: hearings are scheduled for March 21 thru March 25), and instructions to offer public comments.


On behalf of the Steering Committee, thank you.


James Shallenberger

Program Manager | Monitoring & Protection

Susquehanna River Basin Commission

4423 N. Front Street | Harrisburg, PA 17110

Mobile: 717-580-3665

[email protected]



The following is a summary of PA’s proposed MCL. 


EPA applies a drinking water Health Advisory Level of 70 nanograms per liter (ng/L) or parts per trillion to the sum concentration of two sub-groups of PFAS compounds.  PFAS are linked to various negative human health outcomes.  Pennsylvania’s proposed drinking water MCLs are more restrictive than the EPA Health Advisory Level as shown below; however, EPA is currently developing National Primary Drinking Water Regulations for these substances.


Sub-Group PA Proposed MCL (ng/L)


Pennsylvania’s proposed MCLs are applicable to all 3,117 community, non-transient, bottled, vended, retail, and bulk water systems.  Pennsylvania has 1,905 community water systems that serve a total of approximately 11.4 M (million) residents and 1,096 non-transient, non-community systems that serve approximately 0.5 M residents.  Approximately 3 M Pennsylvanians rely on private water systems that are not subject to water quality testing and/or regulation.  Sampling from ~400 sites across Pennsylvania (90% of sites were biased to within 0.5-mile of a potential source of PFAS contamination) demonstrated that PFAS occurred in ~25% of sites.

Here’s a summary of background info regarding PA’s proposed MCL:

The federal government implements the Unregulated Contaminant Monitoring Rule (UCMR) as a mechanism to surveil at least a portion of the emerging contaminants spectrum on a recurring basis.  UCMR runs on 5-year cycles during which up to 30 unregulated contaminants are nominated and sampled to generate national occurrence data.  PFAS were part of the 3rd UCMR and sampling from 2013 – 2015 detected PFAS at concentrations above a threshold of 400 ng/L in 3.4% of monitored water systems.  In 2016, EPA set a Health Advisory Level (HAL) for PFAS (total combination of PFOA and PFOS) at 70 ng/L.  As result of attention to PFAS that were detected in potable water supplies near the Willow Grove (eastern PA) Department of Defense site and coupled with the federal HAL, Pennsylvania developed a PFAS Task Force in 2018 that eventually led to the drinking water maximum contaminant levels now proposed.

What are PFAS?

PFAS stands for per- and polyfluoroalkyl substances, encompassing some 6,000 compounds synthesized since the 1930s, of which two main subtypes currently draw most attention: PFOA – perfluoroacetic acid and PFOS – perfluoroctanesulfuric acid.  PFAS as a group, are heat-resistant, stable, and repel water and grease; traits that ensured their utilization in apparel, upholstery, electronics, metal coatings, and fire-suppression foams.  PFAS have high water-solubility and resist chemical degradation, making them fairly widespread and persistent.  PFAS also bioaccumulate.  PFOA and PFOS are no longer manufactured in the US.

What are known health effects? 

As described in the proposed MCL, PFOA and PFOS are linked to various adverse human health effects including pre-natal development (skeletal and neurobehavioral outcomes), liver toxicity, kidney disease, decreased immune response, thyroid disease, and several cancers.

What is known occurrence of PFAS in Pennsylvania?

In 2019, the Pennsylvania PFAS task force developed a sampling plan to generate statewide occurrence data.  The task force identified 400 sampling sites; 40 sites were classified as baseline (i.e., background) and their selection was based on catchments with >75% forest land cover.  The remaining 360 sites were selected based on proximity (within 0.25 to 0.5-mile) to a potential source of contamination; i.e., military facility, fire training center, airport, landfill, manufacture facility (textile, apparel, chemicals, electronics, metal fabrication, upholstered furniture, leather processing), and known contaminated sites.  Starting in 2019, 412 water samples were collected across Pennsylvania.  PFOA and PFOS were detected in 27% and 25% of samples, respectively.  For “hits”, the mean & maximum concentrations for PFOA and PFOS were 7.5 ng/L & 59.6 ng/L and 9.9 ng/L & 187.1 ng/L, respectively.

How are PFAS treated?

The primary treatment approaches to reduce PFAS in drinking water are: granular activated carbon; anion exchange, and reverse osmosis.

What are the costs/benefits associated with proposed MCLs for PFOA and PFOS?

The narrative describes estimated costs for monitoring and for the specified water treatment approaches according to step-wise reductions below the current 70 ng/L federal HAL.  Under provisions of the proposed rule, water systems will be subject to routine compliance monitoring.  Systems determined through monitoring to be impacted by PFAS will require treatment system upgrades necessary to achieve the MCL limits.

How does Pennsylvania’s MCL approach compare to other jurisdictions?

In the proposed rule, Pennsylvania cited the following existing drinking water-based MCLs (ng/L):

 Substance NY MI NJ NH PA MA* VT**
PFOA 10 8 14 12 14 20 20
PFOS 10 16 13 15 18 20 20

Notes: * Massachusetts assigns 20 ng/L as a drinking water MCL to the sum of 6 PFOA and PFOS substances;

** Vermont assigns 20 ng/L as a drinking water MCL to the sum of 5 PFOA and PFOS substances.