By Skipper Mary
Revision has assumed the role of research vessel and the question about drinking the bay's water straight has been answered.
Ah! A bit of science!
SECCHI DISK
On loan from UW Extension's Citizen Lake Monitoring Network, the 8" black and white metal disk with the line marked in 1' increments had been in our basement for 15 years.
One of our school-age daughters and I had planned to use it for monitoring a Northwoods inland lake and that's as far as that project got. I kept the disk though, hoping someday we could put it to use and now, though that daughter has grown up and moved out, Jeff and I have a sailboat on the bay.
This ingenious water clarity measurement method was developed by an astrophysicist and scientific advisor to the Pope, Father Pietro Angelo Secchi, who dipped the first disk into the Mediterranean in 1865.
These days, in Wisconsin, 1200+ people are dipping secchis off boats and docks, recording the data, then sending it to the DNR where I imagine it gets complicated.
However, using a secchi disk is simple. Just follow the DNR's best dipping practices:
• Remove your sunglasses.
• Go the shady side of the boat.
• Don't dip when there are whitecaps.
• Lower the disk into the water and mark, with a clothespin, ideally at the waterline, where the disk disappears.
• Lower the disk another two feet and mark with another clothespin where it reappears then average the two.
• Record the date and time.
• Record the atmospheric conditions.
As depicted in the photo the atmospheric conditions the day of our first secchi dip were sparkly. Seeing the front moving in I hauled the Cap'n in from the dock, turned off the shorepower, then stood in the companionway filming the sparklies until the rain showed up.
After getting the boat buttoned up the two of us stood in the dim cabin with the Cap'n cocking her head at every cRAAaCK and me being careful not to touch anything metal.
For a moment there was a tinge of electricity, a vellus rush accompanied by the sound at the tail end of a cymbal roll, jjjjsh.
Then the storm passed; the sky was again sunny, and; at 7:30 p.m. I lowered the disk off the swim platform, recording 2' 7".
THE BAY'S DRINKABILITY
While sailing, we've occasionally discussed dipping the canteen and taking a swig as the water looked so good. My crewmate said drinking it straight was a crap shoot; be safe and stick to filling the canteen with tap water.
This seemed like common sense, while my take was historical. Having grown up boating off the Keweenaw and drinking Lake Superior water straight (none of us are, or were, the worse for it) it seemed that drinking tap water while on the bay seemed fussy.
Then last summer a friend was aboard and we were discussing water quality and she asked how clean was the bay as in, Can you drink it?
Wanting to put a fork in it I emailed Todd Ambs, Administrator of Water Division for the Wisconsin DNR, and queried: Is the bay of Green Bay's water drinkable?
His response: In general the answer is yes–with common drinking water treatment. Surface waters naturally contain pathogens that can make humans ill and other constituents that are routinely addressed by the water treatment systems. Green Bay–as it name somewhat implies, has higher concentrations of algae as well. It is not advised to drink any lake water, including Green Bay, without some treatment.
So, okay, we'll continue to refrain from drinking it straight and thank you Todd for setting the record straight.
And thank you, Mary C for asking the question and spurring me into action.
As for water in the news, our hearts are aching over the oil spill in the Gulf. The previously mentioned daughter now lives down there and has expressed an interest in volunteering for wildlife rescue. That would be good! Do it!
For those living or recreating around the bay, we have links to organizations that are working to raise awareness of, and protect, its splendor. 
* * *
For secchi info: Citizens Lake Monitoring Network
Secchi disk graphic courtesy UW Extension