Spring Attack is not a charge or usable in conjunction with a charge. Spring Attack describes a unique full-round action, while running or charging are both their own full-round actions. You cannot combine actions together; if you are using one, you are by definition not using the other at the same time.
You could modify water run to include Spring Attack, perhaps like so:
Water Run: When a member of this race makes a charge or run action, or uses the Spring Attack feat, they can move across the surface of water without sinking. They sink immediately if they end their turn standing on water.
You could go further by adding straight-line requirements on the usage of Spring Attack, too:
Water Run: When a member of this race makes a charge or run action, or uses the Spring Attack feat and moves in a straight line, they can move across the surface of water without sinking. They sink immediately if they end their turn standing on water.
At which point it might be simpler to just say
Water Run: A member of this race can move across water without sinking, treating it as firm, unslippery ground, but only while moving in a straight line. If they attempt to turn, or end their turn standing on water, they immediately sink.
Which would include running and charging by definition (since each of those require moving in a straight line), but also any other kind of movement where the creature moves in a straight line. Note it does have the drawback of no longer allowing turns even when a creature would otherwise be allowed to turn during a charge (e.g. using the Twisted Charge skill trick); further rules could be added to water run to allow those, though:
Water Run: A member of this race can move across water without sinking, treating it as firm, unslippery ground, but only while moving in a straight line. If they attempt to turn, or end their turn standing on water, they immediately sink. If they are capable of turning during a charge, they are also capable of turning while running over water the same number of times during their movement as they would during a charge.
As for official abilities that allow moving after a charge, the only one I know of is the Ride-by Attack feat, but as the name suggests that is only while mounted. It would not be compatible with the water run ability (since the mount wouldn’t have it).
Giving a race an unmounted Ride-by Attack ability would be a pretty good benefit, but hardly unreasonable.
You could also try things like allowing them to count as mounted for feats in general, and then as having Mounted Combat and Ride-by Attack for prerequisites. Something like this:
Powerful Run (Ex): You can use feats, abilities, benefits, and bonuses that normally require you to be mounted even when unmounted. You gain Ride-by Attack as a bonus feat.
You count as having the Mounted Combat feat for prerequisites, but cannot use its benefit. You may still take Mounted Combat as a feat in order to use its benefit. You may also substitute an equal number of ranks in Acrobatics for Ride skill rank prerequisites. If you have a climb speed, flight speed, or swim speed, you may substitute Climb, Fly, or Swim ranks, respectively, instead. If a feat requires Mounted Combat or Ride ranks, and you do not meet those requirements without this feature, you cannot use that feat’s benefit while mounted.
Might have gone overboard on this by this point, but just to give ideas. Feel free to pare this down to a simpler feature as your tastes dictate. Removing Ride-by Attack as a bonus feat would also greatly reduce the power, maybe make it more appropriate with water run. Then the race wouldn't have the ability by default, but would have the option to take a feat for it.
Bear in mind, though, that water run’s significance will drop off quickly, and by mid levels (5-10-ish) it will probably be pointless: by then, most every character should have a way to fly. At low levels, it’s pretty potent, and water run plus powerful run might seem too good. But if you nerf things too much, by mid levels the race may seem rather lackluster.