Waterfront desirability tested in game is 10, range 3.
In augustus/src/building/building.c ,
line 39 40:
#define WATER_DESIRABILITY_RANGE 3
#define WATER_DESIRABILITY_BONUS 15
line 392 393:
if (b->is_close_to_water) {
desirability += 10;
line 638 639
int building_is_close_to_water(const building *b)
{
return map_terrain_exists_tile_in_radius_with_type(b->x, b->y, b->size, WATER_DESIRABILITY_RANGE, TERRAIN_WATER);
So water desirability is defined as +15 range 3, then if " is_close_to_water" it gets +10 desirability, and if "building_is_close_to_water" (not the same thing) then it calls for the defined range of line 40, which is 3.