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Severn River Association

Apr 29

Thanks to our Water Quality crew, Emi, Brian and Steve for checking on oxygen and salinity levels at our oyster restoration reefs on April 16, a bright, breezy, sunny brisk day.

Here’s a sample of a 6-inch bivalve - alive - we pulled up with the anchor at The Peach Orchard reef.

Oysters are doing well at all 5 reefs. Oxygen is great, better than 10 mg/L. Salinity is ok, in 7 ppt range. Clarity hovering near 1.0 m. ... See MoreSee Less

Severn River Association

Apr 24

It's cold out on the Severn In April! Yet, our intrepid Water Quality Teams are braving the weather to get an early start on tracking conditions in the Severn River.

Evidence is mounting in the Creeks of Whitehall Bay that something untoward is developing - the beginnings of an algae bloom like the Mahogany Tide of 2020.

Cheers to Emi, Kathryn, Art and Tom on this cold April 16 morning. We all felt like it was ready to snow!

Despite the cold water, we're finding a plenty of oxygen (well above 5 mg/L) everywhere. That's typical for this time of year.

But we're also finding prodigious algae growth carpeting the bottoms of the creeks. Water temps are in the low- to mid-50 degrees (13-15 degrees C). That's cold for humans, but it's plenty warm for algae growth - and this growth is fed by human activity - mostly lawn fertilizer runoff loaded with nitrogen, which is junk food for algae.

Why do we believe a harmful algae bloom is again likely? A few key observations:
- At the the heads of Mill, Burley and Whitehall Creeks, we found thick patches of filamentous algae (see pic of Capt. Tom hauling anchor). This indicates there's plenty of junk food (nitrogen) in the water for the algae to feast upon.
- Poor clarity readings too, Mill Creek Station #3 Secchi reading was 0.76m and at head Whitehall Creek Station #3, only a 0.64 m reading,
- a brown color in the water despite no recent rains (see pic of the Secchi disk disappearing way too quickly compared to the 1.30 m Secchi readings were recorded in other creeks last week),
- a giant brown spot in Whitehall Creek between Ridout Creek and Whitehall Marina (again, with no recent rain, this does not appear to be a sediment plume), and
- supersaturated oxygen conditions, especially at the surface of the creeks - readings of 122.3% and 11.86 mg/L for dissolved oxygen.

SRA's Field Investigator Emi explains that the high percentage of dissolved oxygen means there is a something creating an overabundance of oxygen in the creek and that "something" is likely the prorocentrum minimum algae that eventually creates the Mahogany Tide conditions that we saw last May in the Severn River system.

We'll be keeping a close watch on conditions every week.

And thank you all for your support support of the Severn River Association.

If you'd like to help keep our water quality monitoring program rolling along this season, please considering donating to SRA at: severnriver.org/donate ... See MoreSee Less