Brook...you can't siphon in both directions...only from high to low points. At best, you would reach equalibrium and flow would stop. Inflow will either have to drain naturally, or be pumped out, if the pond is indeed lower than the stream.
Are you 100% sure your stream is higher? Shhot an elevation from the stream water level to your pond bottom (or anticipated bottom).
Even if stream/pond levels become equal, electrical pumping could be fairly inexpensive since head pressure would be near zero and low wattage pumps could be used.
