State Of The Severn: Mostly, A Good Year!

Published: April 22, 2020


ANNAPOLIS (April 21, 2020) — For the most part, 2019 was a good year for the Severn River, according to the latest State Of The Severn report released by the Severn River Association, the nation’s oldest river group.

The best news was that it was a great year for swimming; the clarity of the water was wonderful in the main stem of the river, and we celebrated a huge expansion of our underwater grasses, which provide habitat and food for fish, crabs and wildlife and erosion protection for shorelines.

The State Of The Severn was presented by SRA Executive Director, Thomas Guay, during a virtual version of the group’s monthly John Wright Speaker Series.

Special thanks to the Eastport Civic Association for helping produce our 2019 report.

To download the written version of the State of The Severn, click here.

To view a video of the presentation, click here.

Passing The Swimming Test

All beaches in the main stem of the Severn passed EPA’s swimming test 100% of the time, thus were scored as Green Beaches, meaning testing showed that they were under the 104 cfu bacteria count that EPA considers safe. This data is collected by Operation Clearwater and the Anne Arundel County Health Department.

In Annapolis, however, the swimming reports weren’t as good for Spa and Back Creeks, which received Yellow scores for passing the EPA test 60% to 95% of the time.

Note: To improve on these scores, SRA is promoting Anne Arundel County’s Responsible Boating Initiative to preserve the great swimming conditions in the Severn River by encouraging boaters to use holding tanks and pump-up facilities.

Explosion of Underwater Grasses

We had a huge increase in the amount of underwater grasses, aka subaquatic vegetation (SAV).

We enjoyed more SAV in the river than we’ve seen in the past 20 years, perhaps more than 400 acres.

SRA’s volunteer SAV Navy identified abundant supplies of Horned Pondweed in spring and Widgeon, Redhead (see pic at right) and Sago Pondweed in summer, as well as the emergence of the non-native, Eurasian Milfoil.

This is great news because more SAV means more crabs, more fish!

Many SAV Watchers hope that the presence of Milfoil is a good sign for the Severn because Milfoil can tolerate murky water better than our native grasses.

As Milfoil emerges before native grasses, it helps filter the water, thus making way for more native grasses. This bodes well for Back Creek volunteers in the SRA Navy, which found a few lonely strands of Milfoil popping up in Back Creek!

Note: Milfoil is considered a vile invasive in fresh water systems. However, in the Chesapeake Bay’s briny waters, DNR considers it a “non-native” that can help with the return of native grasses.

Good Clarity In River — Poor In Creeks

During 2019, SRA created a river-wide, 41-station water quality monitoring program. SRA’s team of volunteers recorded some excellent clarity readings during their weekly tours.

Most of the mid-river monitoring stations got the best grades of B and B- on clarity. Many of the readings were better than 1 meter in the main stem of the river.

The best was 2.36 meters in Little Round Bay.

However, most of the creeks scored poorly, receiving a C, C- and even some D and D- grades due to the influx of storwmater runoff from impervious surfaces that degrades streams and sends sediment flooding into creek headwaters. At right is SRA’s Field Investigator, Izzie Ketcham, working the Secchi Disk to record clarity readings.

Persistent Dead Zone

Despite the amazing resurgence of underwater grasses, the river also suffered from an extended dead zone of low oxygen conditions that lasted most of the summer.

This dead zone (see chart at left) grew to be about five square miles in size, larger than the town of Denton, Md!

This dead zone area inhabited the bottom half of the water column, stretching from midway between Saltworks and Chase Creeks, up through Round Bay and into the area known as The Narrows.

Dead Zone In Brewer CreekThe dead zone also appeared in most of the mid-river tributaries: Weems, Luce, Saltworks, Clements, and Brewer Creeks (aka, the Idle River).

In the chart at right, the red line indicates the dead zone area where oxygen is less than 2 mg/L.

Oysters Survive Challenging Conditions

The good news is that the Dead Zone did not extend to our oyster restoration area, so our oysters are OK. SRA sponsored an oyster dive in 2019 to check on the health of our oysters on four restoration reefs.

The good news: Our oysters survived two years of low salinity.

However, the low salinity conditions stunted the growth of oysters raised and planted in 2018, but they survived!

Our hope is that they start growing again in 2020 now that salinity has returned to normal levels.

Special thanks to Field Investigator, Izzie Ketcham, all our volunteer citizen scientists, SRA members and the Delaplaine Foundation for supporting our water quality monitoring program.

Our ability to create and sustain our water quality monitoring program depends on your generous and continuing support.

If you would like invest in the river’s health, please click here to donate.

For More Information:
Thomas Guay, SRA Executive Director, 443-716-6776,