Big Blue – Lester Milligan Park Mason City

6 Responses to “Big Blue – Lester Milligan Park Mason City”

  1. sabbath999 says:

    We were in town the weekend of June 9-10, 2012, and we thought since we were going to be there anyway, why not take the gear, get wet and see if this spot is actually drivable.

    The short answer for those of you who know the reference: Think Quail Run/Rolla with a bit better vis and more fish, not as good walls (it’s not a traditional quarry) and lots of surface swimmers and you will have an idea.

    A bit of background, this lake is a former industrial clay pit, so the bottom is pretty solid giving the lake a chance to have decent vis (for the midwest). I don’t know how big the lake is in acreage, I would say it is about the same size as PennyRoyal. Max depth is reported to be somewhere in the high 30 feet. The brick manufacturing plant that used this pit closed in the late 60’s or early 70’s, and since then it has been turned into an EXTREMELY nice city park, where all amenities are free (including the diving). The park contains a good bathroom area/changing room (no shower) that is not heated so only open during the temperate season, a skate park, free outdoor roller rink, a nice playground and a public swimming beach. No gas motors are allowed on Big Blue, which means no dive flags necessary. Fishing is allowed, so good, easy to reach line cutters are a necessity at this facility.

    The south western part of the lake features a 10 x 10ish training platform at about 13 feet is located under a buoy approximately 40 yards off shore, far enough out to get away from the sand stirred up by the busy swimming beach. It is linked, by rope, to a sunken boat, just follow the rope on out. The boat is also surface marked by a buoy. Be aware, these buoys were being used as racing targets by a bunch of people in kayaks while we were there, not a big deal but heads up.

    The southeastern part of the lake features a small which juts out into the water a few feet, and from which the local kids completely ignore the “no diving” signs. Local divers who like to “treasure hunt” are constantly finding new items. Be aware, however, that people also sometimes fish from this dock so there may be lures in the water. Traveling east along the gradual east slope, there’s a lot of old junk that has been dumped in the lake dating back to the 1970’s… if you like diving in debris piles (and what self respecting Midwest Muck Diver doesn’t like diving on a 1967 Ford Falcon?) there’s a TON of stuff to see on this side. Lots (and I mean LOTS) of small fish, some very nice aquatic plants… rather like swimming in an aquarium.

    Shore entry is as easy as any place you will ever find, just walk down the swimming beach and into the water. There is also an entrance on the north side of the lake, but we were only there one day and didn’t have time to take a look at it. The locals all use the South side & the swimming beach.

    Big Blue is used for dive training by local dive shops in the area. While we were there, we got a chance to meet the very nice folks from North Iowa Scuba, who are available for air fills in Mason City. They use Big Blue as a training area (not surprisingly) and know the lake backwards and forwards so if you have any questions they would be the folks to ask.

    OK, now the dives. The question everybody wants to know is the vis… while we were there, it was at least 5 feet, ranging up to 10 in several places, and as high as 15 in one spot.

    We did two one-hour dives, both of which we did along the east “wall” since there were divers out on the platform-boats. The wall really isn’t a wall, it is a gentle slope. We dove amongst the rubble piles and spent a lot of time hanging out in the plant areas hanging with the fish.

    We were comfortable in 5 mil, hoods & light gloves, but I would say that would be the minimum you would really want to wear this time of year. Water temp was 76 at the surface, 66 above the cline (at about 19 feet) and 59 below it (we didn’t go lower than 25 feet, not really sure exactly where the lake gets deeper but it wasn’t any deeper than 25 along the east side where we dove).

    The locals were rating the vis as slightly worse than usual. I was talking to one runner/swimmer/triathlete type who swims laps in the lake who told me he can often see the bottom the entire way across the lake. Just reporting what I heard, I make no statement that it was true.

    I will link pictures/vids here in the near future.

    My verdict? If you are in northern Iowa and want to get wet, your options are EXCEEDINGLY limited, and Big Blue is at least something new to do. Would I make a special trip to Iowa to dive it? No. Would I take my dive gear if I were going to the Mason City/Clear Lake/Charles City/Ames area? Absolutely.


    At least SOME visibility
    Friendly locals
    Air fills in town
    Easy entry
    Excellent abundant aquatic life
    Great training or “get wet” diving
    Easy to find


    Public park, so you must lock up EVERYTHING or have a person on shore guard
    People fishing
    Vis can be, and frequently is blown out, call the dive shop for reports of vis.

  2. Sabbath999 says:

    Dove it a couple weekends ago when we were in town anyway (July 4 holiday).

    Visibility was about 10-15 feet, down to 5 in some places. Saw a REALLY nice northern pike (HUGE fish) and a couple that were in the 30-36 inch range, plus a lot of smaller stuff.

    Lots of weeds (but pretty ones). Water temp at the surface down to about 11 was 66, under the cline it was 53.

    This isn’t a dive you drive for, but it is a great training lake and if you are there, it’s a place to get wet. World’s easiest entry and it’s free to dive.

  3. sabbath999 says:

    Me again.

    Dove it a couple weeks ago…

    Vis was 15 feet m/l, lots of plants & weeds. Saw another big ole pike, a real whopper, and had a nice water snake swim by me. That was really cool. It was a nice Northern Water Snake, about a 5 footer, just went past me like I wasn’t even there.

    Dive on, good people!

  4. DivingRat says:

    Dove this weekend (8/30/2014) – with the rain the past several days, the lake was pretty churned up, and the vis was between five (5) and ten (10) feet. Thermocline was at 17′, I was wearing a 3mil with a 3mil shorty over it, that was comfortable; below the thermocline was chilly but not unbearable. 5mil or 7mil would do just fine.

    Saw lots of baby fish (bluegill mostly) along the shore, a couple bigger fish, and a couple bigger bass (largemouth, I think).

    From the platform at the southern shore (marked with a buoy) at 15′ there is a line to the boat, and from there, there’s another line to a second platform in the middle of the lake at about 24′.

  5. Sabbath999 says:

    Diving Rat, you were at Big Blue this weekend too? We may have met met. I am the big guy with the beard, diving with the smaller woman (she doesn’t have a beard 🙂 ), we were those odd folks diving bp/wings & long hose rigs.

    I wore a 3 mil, the wife wore a 5. Vis was not as good as usual, but there was enough to make it worthwhile. Saw some NICE bass over on the east wall, just where the shoreline juts out.

    We dove it Sunday & Tuesday, 5 dives total.

  6. Jason Kupzyk says:

    I know this an odd question and if it is not allowed please let me know or delete it. I am researching for a book and I found a legend of a monster turtle that lives in this lake. It is described as having a shell the size of the hood of a car. If you have seen something like this in this lake or have a strange encounter while diving anywhere please contact me at Thanks! I enjoy reading everyone’s posts about their dives on this page.

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