SRA Volunteers Monitor Severn River Health

Published: June 17, 2019

Annapolis – June 12, 2019: Great news: SRA’s volunteer are already hard at work monitoring oxygen and salinity levels in the Severn River and its creeks.

3 WQ CrewThe weekly tours on Wednesday and Thursday mornings track the growth of the river’s health, which sadly, does include permanent dead zone in the middle of Round Bay.

At left, say hey to Evan from Ben Oaks, Theo from Pendennis Mt., and  Mackenzie, our Team Leader from Edgewater.

We have a mix of good and bad news when it comes to the dead zone.

The bad is that the dead zone is there, lurking at the bottom.

Our crews detected it at the southern entrance to Round Bay where oxygen was a dismal 0.31 mg/l at 8 meters and it was 3 meters thick! Oxygen only returned to good at 5 meters, where we recorded 5.94 mg/l.  (See:

And again near St. Helena’s Island facing the Green Cathedral, we had poor oxygen levels: 1.75 mg/l.

Yet, on the back side of St. Helena’s, near Smith Marina, we found a good reading at Palisades Beach, 6.66 mg/l of oxygen! Yeah!

But the bad news returned up again at The Narrows where we found another horrible reading, 0.55 mg/l oxygen at 5 meters. Things were only marginally better at 4 meters where oxygen tallied 2.39 mg/l.

As the water heats up, we expect the dead zone to expand. Last year by late summer, it reached all the way down to Weems Creek!

Oyster Reefs Enjoy Good Oxygen

Fortunately, there is good news to report, as well. Our WQ Crews also keep an eye on water quality around the oyster reefs we’re restoring with our partner, the Oyster Recovery Partnership, via the Marylanders Grow Oysters and Operation Build-A-Reef programs. 

KathrynHere’s WQ Crew member Kathryn from Sherwood Forest, taking oxygen readings at Weems Upper, one of our Operation Build-A-Reef oyster restoration sites.

Here’s WQ Crew member Kathryn, from Sherwood Forest, at Peach Orchard station over one of our oyster restoration reefs. We recorded 5.67 mg/l oxygen down where the oysters are forming a reef in 3.5 meters of water.

A Thank-You Shout Out!

SRA’s Water Quality Monitoring program is made possible with support from the Delaplaine Foundation and our crew of dedicated volunteers and boat captains, the WQ Crew!

And, all these tours are possible thanks to volunteer Captains like Doug (in red) from Forked Creek, Jim (in blue) from Sherwood Forest. Not pictured are Captains Mark from Palisades and Mike from The Downs.

So far, the oxygen WQ data is looking pretty good for oysters!

Some recent highlights recorded by our WQ Crew:

On May 29, oxygen was 6.56 mg/l on the bottom of the river at Eaglenest point, the former home of an oyster reef. Any reading of 5 mg/l oxygen or higher is considered good for oysters, fish, crabs and other critters.

Mackenzie at Traces HollowOn June 13, when the WQ Crew visited our Operation Build-A-Reef station at Weems Upper, they recorded 6.02 mg/l where our baby oysters were planted last year in 3 meters of water.

To the left is Team Leader Mackenzie, recording a 6.26 mg/l oxygen reading at the Marylanders Grow Oysters (MGO) reef by the Rt. 50 Bridge.

You can see the orange MGO reef marker in the background.

Super Low Salinity

Salinity is a totally different story.

Normally, salinity in a brackish river like the Severn is expected to be in a range of 8- to 15 parts per thousand (ppt), also known as practical salinity units (psu).

However, we’re not finding this kind of salinity anywhere. Instead, salinity in our river has collapsed. Everywhere we monitor, salinity is hovering around 4.10 (psu).

DFM on ShellIt’s due to the freshening of the river that we’re seeing the proliferation of dark false mussels everywhere we look. DFM on line

They’re inside oyster shells, on rocks, pilings, even the ropes used to hang the MGO cages from piers.

This year’s low salinity levels are due to all the rain we’ve had over the past two years. Last year, we had twice as much rain as normal.

Photos: Lisa Borre, Tom Guay