I am sorry, but no dog belongs at a dog park until you have 100 percent recall even with distractions. Find a trainer, preferably one who would rather train smart with POSITIVE training than an electric collar. Electric collars may have a place for aversion (rock eating, bee chasing, snake avoidance), but in the world of GOOD training, there is no place. I am glad that much of Europe has banned them… and guess what, they still train their dogs without. It is a lazy, abusive method. It is one area that EEE and I utterly disagree on but one that I have the support of the massive amount of trainers, researches who have proven time after time after time that NO SHOCK COLLAR comes close to clicker or other positive methods.
http://www.examiner.com/article/tapping-into-the-touchy-subject-of-tap-technology-aka-dog-shock-collars
Call it remote training, tap technology or static stimulation training, electronic collars are certainly not welcomed from a dog's perspective. Karen Overall, a veterinarian specializing in animal behavior, also claims that when shock is used, there is always some damage, even if it is not readily observed.
No dog owner really needs to use a shock collar to achieve his or her goals. Shock collars are used to deliver punishment for unwanted behaviors, and, as seen in the study, put a significant dent in the dog and owner relationship and bond. While this type of training may be effective, why not focus on rewarding wanted behaviors instead, so to create a better and stronger bond with the dog?
http://www.critters360.com/index.php/reasons-why-clickers-are-better-than-shock-collars-in-training-dogs-1578/
And even the famous Robert Milner, dog hunting trainer, who used them for decades
http://www.shotgunlife.com/wingshooting/wingshooting/expert-dog-trainer-robert-milner-says-heck-no-to-shock-collars.html
Compulsion training is not a function of cruelty, he insisted. Shock collars appear to offer a fast track for the average sportsman who holds down a full-time job while juggling family obligations.
“The shock collar industry has convinced him it’s the quick and easy way to train a dog, and that’s total B.S.,” Mr. Milner observed. “Once again, studies have shown that in fact positive training yields 300-percent faster results at a fraction of the cost. Plus the sportsman ends up with a better dog and a much better relationship with the dog.”<<
http://drsophiayin.com/blog/entry/are-electronic-shock-collars-painful-or-just-annoying-to-dogs-a-new-study-r
I have to stop now… my prejudice against using a shock collar makes it a topic I cannot "discuss" because it boils down to a basic belief that if you can train a dog without it, why would you? And since every study shows dogs can be trained as well or better without them, even in hunting recall ... why use them? Sure, you might get a faster response. But then, if your spouse put one on your or your children, they might get a faster response too. Is that how you want to train? If so, maybe a goldfish is a better option.
Or take your dog HOME, work for a few weeks on getting a perfect recall, then work on that recall with distractions, then try out the park. I have seen hard very "on" dogs brought off the freaking Schutzhund field with a recall and never have been touched with an e-collar of any setting. I know hunters who never use e-collars but DO have a sound buzzer so the dog can hear/be reminded. There are tools, and then there are lazy punitive methods. I prefer to leave e-collars for life/death situations that cannot be avoided. (snakes/rocks) You don't have to go and should not be at a dog park until you take the time to TRAIN a 100 percent recall. Or find one that has enclosed fencing.
http://www.clickerlessons.com/recall.htm