The start of the 2019 search for underwater grasses, the fabled submerged aquatic vegetation (SAV), officially shoved off, figuratively speaking, last month with the season’s first meeting of the famous SAV ‘Navy’ at Union Jack’s.

The ‘Navy’ was formally launched two years ago when Brooke Landry with the Maryland Department of Natural Resources linked the Severn River Association (SRA) up with a $12,000 grant from the Chesapeake Bay Program.

That grant allowed SRA to purchase mapping and monitoring equipment to track the return of underwater grasses in the shallows of the Severn River.

Brooke was on hand April 16 to talk about the types of SAV we have in the Severn River (widgeon, redhead, sago pondweed, horned pondweed and and the non-native, Eurasian milfoil).

Brook also provided updates on the types procedures the SAV Navy will follow as they head out — in kayaks and other paddle craft — to map and identity the types of grasses in the Severn River. She explained that the SAV we see today is a visible clue as to the status of water quality today.

The More SAV, The better!

The more grasses growing in our waterways, the better the water quality will be.  When grasses disappear it’s because the water is clouded by sediment, nutrients and algae blooms, which block sunlight.

The great value of the grasses, she explained, is that SAV provides habitat and hiding places for fish and crabs and that the grasses themselves help filter and clean the water and they provide protection from erosion caused by storms and power boat wakes.

Tom Guay, the Skipper of the SAV Navy, gave a history of the underwater grasses in the Severn River as tracked by 30 years of aerial surveys by the Virginia Institute of Marine Sciences (VIMS).

Just a couple of generations ago, before the 1980s, there was so much SAV in the river that it was considered a nuisance and hazard to navigation. But what most residents didn’t realize at the time was that those thick beds of SAV were habitat for crabs and fish hiding until they could become mature enough to venture out on their own.

The river was so clear them, old-timers say, that you could watch crabs start to shed shells and turn into the delectable soft-shell crab. Those were the days.

But with the coming of I-97 and Rt. 32 in Millersville and Severna Park, came rapid development that inundated the river with sediment runoff and nutrient pollutants that degraded water quality.

Then almost overnight, the SAV disappeared. Fishing and crabbing declined with the loss of the grassy habitat.

This first map to the left is the era 1983-1994. According to the VIMS surveys, there was no SAV in the Severn River.

Then in 1994, the grasses start returning as the river rebounded from the insult caused by rapid development.

This second map to the right  is based on VIMS survey in 2006 when the Severn River experienced its most plentiful year for SAV.

You can see a speck of purple at the bottom left. This is an SAV patch just south of the mouth of Weems Creek.

Since 2006, SAV acres have retreated from this high mark and they have ebbed and flowed since then. Currently we enjoy about 230 acres of SAV.

If you’d like to be part of the action to map and identify SAV, there’s still time to enlist in the SAV Navy!

Here are a few enlistees signing up to be part of one of 9 SAV teams that will map and monitor our underwater grasses in 2019.

If you’d like to get in your kayak and help out, email Tom Guay at: TAGuay@severnriver.org.

Put SAV Navy in the message box.