public void setWaterHeight(float waterHeight) {
        this.waterHeight = waterHeight;
        this.plane = new Plane(Vector3f.UNIT_Y, waterHeight);
        if (material != null) {
            material.setFloat("WaterHeight", waterHeight);
        }
        if (reflectionProcessor != null) {
            reflectionProcessor.setReflectionClipPlane(plane);
        }
    }
Sets the height of the water plane
default is 0.0

@param waterHeight the desired height (default=0)
jme3-effects/src/main/java/com/jme3/water/WaterFilter.java