Probably because the entire area is a watershed for the bay. No need for lakes, we have the Chesapeake bay, ocean and rivers. For whatever reason I don't get as excited by fresh water. When you fish saltwater you never know what is gonna be on the other end of the line. And you get the surf.
Maryland does win the best looking state flag award!
Here in North Carolina, the state health department is warning everyone not to eat most of the salt water fish because of the high levels of mercury. The selection of fresh fish at the stores in the Raleigh is poor in comparison to what I was used to in the DC area. Being told not to eat it kind of cuts fish out of my diet, and I love eating fish, salt or fresh water.