CALIFORNIA, Md. – Elevated bacteria levels following summer rainstorms — along with a separate blue crab die-off in the lower Potomac River — are raising health and environmental concerns in Maryland, according to watershed groups and state officials.
Most Sites Fail Bacteria Standards
According to a July 10 report from the Arundel Rivers Federation, all monitored sites failed water quality standards for recreational swimming except for Arundel on the Bay and Columbia Beach.
“Every site failed this week except for two on the mainstem bay,” the group stated. Samples are collected Thursday mornings and processed by Anne Arundel Community College. Results are measured against the EPA’s recommended limit of 104 cfu/100mL for enterococcus bacteria, which signals the possible presence of harmful pathogens.
The group warned that “bacteria levels can increase after major rain events” and advised the public to avoid swimming for 48 hours after rainfall, avoid entering the water with open wounds.
Upper Potomac River Shows Sustained Contamination
The Upper Potomac Riverkeeper reported July 11 that most of its sites failed Maryland’s geometric mean standard of 126 MPN for E. coli, even if some single samples were within acceptable limits.
“There are several sites that are below the 410 and even the 126 level as a single sample,” the group said. “But most of the sites failed the geometric mean limit of 126.”
The geometric mean reflects contamination trends over time and is used to evaluate overall public health risk. “If the geo-mean is red and the single sample is red, then there is a very high risk,” the group added. “This is especially for children and adults with immune deficiencies.”
According to the group’s July 3 report, this is the first time in three years that all testing sites have failed for two consecutive weeks. Contributing factors include “upstream sewer failures that are being worked on, permitted Combined Sewer Overflows that occur in Cumberland, significant rain events washing off our pavement and our farms, and the extreme heat we are having has increased the river temps.”
Potomac Riverkeeper Network Reports Mixed Results
The Potomac Riverkeeper Network noted improvement downstream in a July 12 update but warned of shifting conditions.
“Most sites downstream [were] meeting water quality standards,” the group said. “This data may change after a heavy rainfall as stormwater runoff contributes heavily to bacteria concentrations by washing trash and pollutants into storm sewers which may overflow and dump into our river.”
On July 3, the network reported that “ALL sites in the Upper Potomac have failed to meet these standards.”
Shellfish Ban Issued in Lower Patuxent River Due to Sewage Spill
Following a sewage spill over the July 4 weekend, the Maryland Department of the Environment (MDE) imposed an emergency shellfish harvesting closure in a section of the Lower Patuxent River near Solomons. The closure took effect July 5 and will remain in place through July 26.
The affected area includes all waters east of the Gov. Thomas Johnson Memorial Bridge and north of a line drawn from the southern end of the bridge to Sandy Point. The closure specifically restricts harvesting in Town Creek, Back Creek, St. John Creek, and Mill Creek, according to a notice published by MDE.
The agency said the order was issued to protect public health, as shellfish such as oysters and clams can retain harmful bacteria and viruses after being exposed to contaminated water. Harvesting in the area is prohibited until further notice.
Crab Die-Off Caused by Low Oxygen, Not Algae
In a separate development, the Maryland Department of Natural Resources (DNR) confirmed that a recent blue crab die-off in the lower Potomac River was due to low oxygen levels — not harmful algal blooms.
“A recent die-off of blue crabs in the lower Potomac River is likely due to low oxygen levels, not harmful algal blooms in the water,” DNR said. “Strong winds likely pushed surface waters eastward, allowing oxygen-depleted bottom waters to rise into the shallower areas along the western shore and lower Potomac River, impacting crab pots placed in these areas.”
DNR continues to monitor the situation and will provide updates as needed.
To report large accumulations of dead fish or aquatic life, call the Maryland Department of the Environment at 800-285-8195 during business hours or MEMA at 866-633-4686 after hours.
Public Health Guidance
Watershed groups and public health officials recommend the following precautions:
- Avoid swimming for 48 hours after rain.
- Stay out of discolored or murky water.
- Do not swim with open cuts or wounds.
- Wash hands after water contact and before eating.
- Extra caution is advised for children, pets, and immunocompromised individuals.
For the latest site-specific testing results and advisories, visit SwimGuide.org or contact your local health department.
Contact our news desk at news@thebaynet.com
Another reason to jack up the prices
I have had significant runoff of silt from a neighboring farm as they remove trees and clear the land. It goes into my creek. I have notified authorities but they haven’t done anything. I at least wanted a silt fence at the gulley but got nothing. You reckon that silt is suffocating my crabs. This is where it starts. All because they don’t want to require a millionaire to put up a silt fence. Now if it were me…..