Dresden Files: Special Thresholds: Circles and Running Water

The Dresden Files RPG Rules As Written seem to consider magic circles and running water to be subclasses of wards and thresholds (respectively). They don't provide much guidance on the matter, which is surprising, given how important both elements are to the magic in the series. I wasn't satisfied with these explanations, and created my own rules for handling circles and water. These rules have not been playtested; if you see this and decide to try them out, please let me know how they work in practice.

Circles
Treating circles as just a type of ward or summoning container ignores one of the most important aspects of a circle: anyone can create one. You don't need the slightest bit of magical ability to create a circle, just the physical shape of the thing and concentration. Circles are also supposed to be a potent defense against magic and ectoplasmic constructs. My rules reflect all of these factors.
 * Circles are a type of temporary threshold. For rules purposes, circles just do what thresholds do: prevent magical energy from passing through. Like other temporary thresholds, circles can be worn down through attacks. Keep in mind that circles only block magic. A demon inhabiting an ectoplasmic construct couldn't reach through the circle to grab you, but it could throw a mundane rock at your head.
 * Circles are a component of thaumaturgy, but do not replace wards or containment spells. While using circles in thaumaturgy, you still get all of the effects described here, but you shouldn't trust your life to them. Wards have fewer restrictions than circles, and containment spells can (and should) be much stronger than even a good circle can be.
 * Circles have a strength of 5 + the creator's Discipline. Like other thresholds, a circle's strength acts as a block for ectoplasmic constructs and removes shifts from spells. Even a weak circle is a strong defense against magic and many supernatural creatures. Aspects cannot be invoked to improve a circle's strength.
 * Creating a circle is a maneuver made with Discipline. Once you use this maneuver, you get the circle, as well as an aspect: Standing In A Magic Circle. You can tag and invoke this aspect as normal, but so can anyone else. The aspect lasts exactly as long as the circle stays together.
 * The creator of the circle can defend against magic with Conviction, Discipline, or Lore, whichever is better. If a magical effect or creature would overcome a circle's strength, and thereby get past it to either weaken the circle or affect the creator, the creator can defend against the magic using the best of those three skills. Aspects can be used here by either side to improve the attack or the defense.
 * If the circle is broken, its protection ends immediately. This covers two main situations:
 * The creator cannot take any action that would literally or symbolically break the circle. Creating a circle is an exercise of will to create a metaphysical wall around a place. If that will is redirected to project outside the circle, the circle loses its power and ends. This can be anything from trying to cast a spell through the circle to walking through its borders to shooting a gun. In all cases, the creator's intent has changed, and the circle loses its effects. Circles are a completely passive defense.
 * Nothing can physically break the circle. If the circle is just chalk on the ground, wiping or washing away the chalk would break the circle. (This is why having a permanent circle set into the floor can be an advantage.) Just walking over a circle doesn't break it, but if it ceases to be a physical circle, the energy grounds out and it stops working.

Running Water
The game rules definitely consider running water to be a form of threshold, but that seems irregular to me. First, they don't provide any guidance on how strong the threshold should be; second, thresholds can block ectoplasmic creatures, but most such beings (like a demon's construct body) aren't supposed to be limited by running water.
 * Running water is a special type of threshold. It reduces the power of spells, but it does not block most supernatural creatures and cannot be worn down by receiving stress. At the GM's discretion, some creatures, like Black Court vampires, can be blocked by running water.
 * The strength of running water depends on how much water there is.
 * Strength 1 = light rain, modestly-sized stream.
 * Strength 2 = heavy rain, slow river, large pond or small lake.
 * Strength 3 = torrential rain, large and fast river, large lake.
 * Strength 4 = typhoon, ocean.