How did the Department of Health respond to the December 17, 2005 sewage spill at Mill Creek?

On the day of the sewage spill at Mill Creek (December 17, 2005), the Department of Health issued an emergency closing and warned against swimming and other direct water contact in the creek.

To evaluate water quality conditions following the spill, the Department identified five locations for collecting water samples. The locations were near Haskell Drive, Mill Harbor Drive and Ferry Point Marina along Mill Creek; Twin Harbors along Dividing Creek; and Moorings on the Magothy at the Magothy River.

The Twin Harbors and Moorings on the Magothy samples were used to assess areas beyond Mill Creek. All of the Twin Harbors and Moorings on the Magothy samples were found to be at acceptable levels for recreational water use during non-peak seasons.

The Department of Health reopened Mill Creek on January 20, 2006. The creek was reopened once test results from samples collected from Mill Creek showed that the water met standards acceptable for swimming, boating, kayaking, canoeing and other direct water contact activities.

Water quality conditions at the four locations on Mill Creek were monitored by the Department of Health on a monthly basis through the spring and on a weekly basis during the 2006 swim season (from Memorial Day to Labor Day). Water Sampling Results and Locations

As part of the Department’s seasonal community beach water quality monitoring program, samples from Twin Harbors and Moorings on the Magothy were collected monthly from Memorial Day to Labor Day. For information on the Department’s community bathing beach monitoring program, click here or call 410-222-7241.

For current information on advisories or closed county waterways, visit Advisories or Closed County Waterways

For information on restrictions on crabbing or fishing, visit the Maryland Department of the Environment

Three water samples are collected at each sampling location. Water samples are iced and shipped by courier to the Maryland State Laboratory. Samples are tested for enterococci bacteria.

For more information about enterococci, see fact sheet, Water Quality and Swimming or Fishing in Anne Arundel County Rivers and Creeks.

A certified laboratory participates in proficiency testing and on-site certification inspections to ensure strict guidelines, standard methods and laboratory protocols are being followed during sample analysis. The water samples from Mill Creek are being analyzed by the Maryland State Laboratory, which is certified to perform the test for enterococci bacteria. The use of a certified laboratory assures that quality control standards are being met and increases the level of confidence in the water quality test results.

The State of Maryland Bathing Beach regulations are used to determine water quality standards for swimming and recreational use. These standards are also used to test waterways after a sewage spill.

A laboratory test for enterococci bacteria is used to measure fecal contamination in water. This test is recommended by the U.S. Environmental Protection Agency.

Results from three water samples taken from a location are averaged to determine the bacteria level at that location. The water quality standard for locations along Mill Creek is 500 or fewer enterococci organisms per 100 milliliters during the winter and spring months and 275 or fewer during the summer swim season.

Emergency closings are issued when a recreational waterway has been impacted by a sewage spill greater than 10,000 gallons. A health advisory is issued when a recreational waterway has been affected from a spill between 2,000 and 10,000 gallons or when unacceptable enterococci levels are found from routine water quality testing at community bathing beaches.

Information on emergency water closings or advisories is available on the Department of Health’s Web site, and Water Quality Phone Line, 410-222-7999. Information on any emergency closing and health advisory is released to the local media, and signs are posted at the affected community beaches.

NEW - The Department of Health has developed a notification system that will allow anyone, including individual residents, businesses and community association leaders, to register online and receive e-mail alerts when emergency closings and health advisories are issued in response to a sewage spill or high enterococci counts anywhere in waters monitored by the Department of Health. The notification system is accessible through the Department of Health’s Web site. Recreational Water Quality E-mail Alert System.

Based on results from air monitoring sampling, the Department of Health concludes that hydrogen sulfide levels measured at the Mill Creek pumping station pose no health risk to the community.
DPW Mill Creek Hydrogen Sulfide Testing Report

The Department of Health asked the County Department of Public Works to provide air quality monitoring data to measure hydrogen sulfide levels in the area of the Mill Creek pumping station. Hydrogen sulfide (H2S) is a colorless gas that can be generated in sewer systems from the breakdown of organic matter. It has a rotten egg odor which can be detected by 50 percent of people at levels as low as 0.0047 parts per million (ppm). Odor is not a useful indicator for health purposes, because noticeable odor can occur below levels of health concern and the odor may disappear at high levels.

In May 2006, an independent consulting firm under contract with the Department of Public Works performed hydrogen sulfide monitoring around the Mill Creek pumping station. The consultant’s report shows that hydrogen sulfide levels ranged from 0.007 to 0.013 ppm during screening tests conducted on May 4 at 11 locations around the pumping station. According to the report, the detected levels were well below the ERPG-1, which is the lowest hydrogen sulfide guideline value currently available. The report describes concentrations of hydrogen sulfide at four locations around the Mill Creek pumping station during the 2-week continuous monitoring period (May 9 through 23) that were below limits of detection. The certified industrial hygienist reviewed the air quality monitoring data comparing these results with a variety of air standards and concluded that the hydrogen sulfide concentrations around the pumping station do not pose a health risk to the local residents. The Department of Health completed a review of the consultant’s report and agrees with these findings.

To review a complete copy of the consultant’s report, see Mill Creek Hydrogen Sulfide Testing Report

For more information about recreational water quality, contact the Recreational Water Quality Program, Anne Arundel County Department of Health, 3 Harry Truman Parkway, Annapolis, MD 21401, 410-222-7241, Monday thru Friday 8 a.m. - 2 p.m.

More information can be found by visiting the Department of Public Works.