When applying fertilizer or putting out seed, I am a little anal about it but I apply at half the rate and walk the with a broadcast spreader then I apply again at half rate and walk the yard again in a criss cross pattern. If I had a big yard I probably wouldn't do that but at the very least use a broadcast spreader and not a drop spreader.

I think they will just make a mess with their droppings. I don't think they will "dig" up any plants.

I hate to say this, but your problem is normal. Ducks and geese will want to spend much of their time on land, eating tender grass shoots, insects, garden plants, etc. Most places that have populations of these birds live to regret it. At least in those locations where the bird and human environment are in close proximity. People that build those large water features as an amenity and don't understand how ducks and geese will use it are creating a real problem for the property owners. As you well know. Adding another pond will likely add to the problem rather than mitigate it. Well, there are a number of spray on repellents that you should try. They will work for awhile. You should also use scare tactics such as imitation reptiles (large), in combination with the repellents. I think that motion activated sprinklers would help, too. The noise and water would startle them. In my city, there is a small lake built within the campus of one of the universities. Ducks and geese pretty much took over the location, creating a health hazard and ruining the landscaping and grass. Repellents worked for a while, as did a remote operated car used to chase them all over the place (hilarious). But the thing that has really helped is the installation of three large alligator decoys that float all year long in the lake. They are secured to the bottom with weights and chains. The population of birds on that lake has been greatly reduced! (Not eliminated, but reduced.) Type in 'goose repellent' into google and do some reading. I think that with a combination of simple things, you can keep the ducks and geese away.

cutlas, Is it this type of diagonal pattern, or something different? This is just a product of mowing the lawn in a diagonal pattern. This was early on in the year, so you can't see the cross pattern, but I generally alternate the angle I cut so that it makes a nice criss-cross pattern on the lawn. Commercial mowers will leave a more distinct pattern than this - usually much wider, but with a regular homeowner mower, you can get a pattern. The real key is having a healthy lawn. The greener the lawn, the more distinct the pattern is (in my opinion). My bluegrass is cut to 4", which certainly helps the pattern show up, too. The pattern is created by the blades being pushed in opposite directions as the mower passes over them. This allows them to reflect light differently, thereby making the cutting pattern noticeable. Believe it or not, this is the exact same principle used in baseball stadiums to create the great patterns you see there. I've not personally tried it, but I heard someone mention one time that you can put a piece of rebar in the little black flap on the back of the mower to help 'encourage' the grass to lay in the direction you are mowing. That would make the pattern even more noticeable, though I'd be careful not to mash it down too much.