How did I miss this? Sorry to chime in late....I love garden raving, I'm not nuts, just passionate about it.
What is the obsession with keeping plants that don't want to grow here? HereFishy is right. The light, pH, and nutrient levels are all wrong for us to be keeping lawns. I would suggest trying eco-lawn or eco-turf. It really cuts down on the maintenance.
I hate mowing so I may be biased. I collect too many trees, shrubs and perennial plants to afford space for lawn and if I want to look at lawn, well everyone else has it.
SBLvr, if you must keep lawn, I can help.
How old is your lawn?
Was it seeded or sodded? Has it been overseeded lately?
How many hours of direct sun does it get late June/early July?
Any moss? Stringy or clumpy?
What kind of weeds do you have growing in it?
How long have the yellow patches been there? Check out IPM on this site to see if you have a problem with Crane fly larvae AKA leather jackets.
http://www.seattle.gov/util/Services/Yard/Natural_Lawn_&_Garden_Care/Natural_Lawn_Care/index.asp
What has changed?
-Do you have a new puppy? Active kids? Rogue mole? Was there big lumps of snow on those yellow spots during this winter? LOL-Are you emptying your skimmer cup on it to reclaim the nutrients?
How do you use the lawn? Wear and tear-Just watch it grow or play rugby on it?
What's the current maintenance of it?
-water (frequency/duration), fert, lime, aerate, de-thatch, moss-control, weed-control, pest-control.
What is the soil like in that area? New topsoil over glacial till, mostly clay?
We really don't need to water just yet, its been a pretty cool spring so far but I'd see what the texture (% of sand, silt, clay) and structure(the arrangements of those particles) of your soil is before you go nuts on the water this summer. You can always take a sample of it to a Master Gardener Clinic and they can look at it for you free of charge. There is a pretty good debate in the local hort circles about letting your lawn go dormant for the summer vs. keeping it green. Not to mention the water restrictions the last few years.
Seeing as you're in Everett, chances are pretty good that you live on the same cruddy clay that everyone else has around here. Don't add sand, you'll end up with concrete and then you'll really have water movement issues.
If you weren't considering eco-turf b4, I'll bet you look into it now. LOL! Oh, and there's also that fake lawn that has recently hit the market. Fuzzier than astro-turf but still feels weird (kinda plasticky looks great though, no yellow spots). Hope I can help, I know that those are a lot of questions but believe it or not it will help figure out what's wrong, how to fix it, and hopefully make it easier to take care of.
I'd avoid the weed-n-feed type products. The feed is highly soluble, washes away with our rain and the weed doesn't become active 'til the soil temps are up around 50-55, weeds get the jump start. Not to mention the chronic exposure related health issues. Healthy soil and turf will resist weeds, pests and disease. (Boy, this is starting to sound familiar.) Look into an organic pre-emergent treatment or spot treat with non-selective herbacide. The products containing acetic acid and clove or cinnamon oils are good, and safe if you go to play on the lawn after 24 hrs. I'd watch the minimum active temps on the glysophate products(round-up, etc.) as they are the most effective when air temps are 70+ and it doesn't rain for a couple of days after application. Again health concerns with the glysophate. Read the label, suit up. It's the long term exposure to read up on....scary.
I can't contribute much on the reef side so there's my .02 about ornamental turf grass.
My favorite tools for dealing with slugs and snails is a pair of chopsticks and a jar of old tank water. FIZZZzzzzz. That or the flameweeder, they bbq up pretty good. They're cannibals ya know, smush one and the next morning 20 of his buddies are scraping him off the sidewalk. Happy hunting.