Spring Swim Anyone?

Pine Lake Swimming/Fishing docksIt's that time of year when those of us that are in training all-year yearn to leave the pool and venture out into the open water. In the Seattle area the time frame available for outdoor swimming is limited due to... any guesses? (Should be obvious) And while that rain is melting the glaciers and snow pack the lakes remain cold well into June. How cold? Are the lakes in any condition for swimming? I took my kids on a field expedition to a couple of local lakes to find out.

“Is the lake sick Dad? Why do we need to take it’s temperature?”

“Because I’m not jumping into water that’s under 55 degrees.”

 “Why would you want to jump into cold water?”

“That’s a very good question, son.”

The last time I experienced a cold water swim was the 2010 Issaquah Tri where the water temp was about 57F (see race report for full details). It was a weird experience where I could not get my arms working and ended up doing the breast stroke for 400m. U-G-L-Y.

King County is nice enough to provide detailed lake conditions on their website which includes water temperature as well as bacteria and algae levels. In other words: data heaven. (Nerds rejoice!) 

I used an Acu-Rite Wireless Digital Cooking and Barbeque Thermometer purchased from Woot.com a few years back. OK, so it's not exactly a scientific instrument. The last time I used it was to check the temperature on a pot roast. It may not be scientific but it does give a relatively accurate reading.

Thermometer Reading at Pine LakeAfter letting the sensor sink down as far as possible we waited. It refused to exactly straighten out thanks to the metal cable on the sensor which is typically wrapped tightly around the base. The temperature settled at 56F at a depth of about 2 feet.

To verify we took another reading close to the shore which would be slightly warmer due to the minimal depth. The ducks were very interested in our little sensor sitting in the water which delighted my kids. After heroicly fighting them off (with a camera flash as I took their pictures) we were able to read a temp of 57F, just as expected.

The short answer: the lake is almost ready for swimming! At least this lake is almost ready. Lake Sammamish, where I did most of my summer training last year, is another story completely. That lake is almost entirely glacier-fed and much colder. Snow melt holds the temp anywhere from 5-15 degrees colder than Pine Lake which is entirely rain-fed. According to the King County buoy site the temp today is 49F. I would say that makes it 8 degrees colder but that wouldn't be entirely accurate. In order to get a firm comparison I took the thermometer to Lake Sammamish and to do a similar test.


Thermometer reading at Idylwood ParkThe location of choice is Idylwood Park where the City of Redmond has setup a 100 yard buoy line during the summer months where their lifeguards can supervise. The City of Bellevue has a similar setup at Meydenbauer Beach Park. Idylwood is a favorite training area for local triathletes with its close proximity to Microsoft and other local tech companies in Redmond and Bellevue. It also has a dock that goes out into the water. This allows me to take a reading away from the shore similarly to what I did at Pine Lake.

The results: 52F. Brrrr!

I think I'll be waiting a bit before I don the wetsuit and swim a few lap s at Idylwood. Pine Lake and the other rain-fed lakes are just about ready for some limited open water swimming.

Conclusion: Almost, but not quite. With a few more warm days the temps should be tolerable with a full sleeve wet suit. If we get a warm day this week maybe I'll take a long lunch and try out Pine Lake.