Leash Law for dogs – how to enforce it?

So the title says it all. According to my research there is a leash law in Houston area/Harris county and all pets( dogs) has to be on the leash in public places, such as parks with explicit notifications at the entrance. But most of the big dog owners of ( Rottweilers/ Labradors) let them roam free, without any leashes or muzzles on kids playgrounds/trails and do nothing when these dogs chase runners, bikers, strollers with babies. Sometimes they say something like “no worries the dog won’t bite” but I don’t want to guess what is on that dogs mind and it freaks me out whenever big dog/dogs chase me or my kids. There are always explicit signs in the parks about keeping dogs on the leash at all times but dog owners ignore it. How can I protect myself and my kids in public parks from dog owners and their big dogs who chase me?Call police? Spray the dog? Aren’t there special parks for dogs?