Lake swim--and my wobbly progress...your input?

Hi folks, Recently did an "aquathlon" including a 1/4 mile swim/5k run. I'm more a runner than a swimmer at least at this point, but as the username suggests, I'm also looking for the swimmer in me. This event was a lot of fun and a way to wed the two interests together. I was quite happy w/ the run, which was my fastest time in the distance this year. And I really wasn't too unhappy w/ the swim considering I'm a newbie at this business. But I'm interested in your feedback on how to improve on that. A few facts: the lake is smallish (New Englanders might call it a pond) and very, very murky. I took a quick swim b/4 the start and felt some sort of rusty metal objects under the surface, so when it was time to start, I chose to start off to the deep side a bit. (Was told the deep side was about 8 feet.) Theoretically one could wade the "swim" section, but I had no interest in doing that. My time as I came out of the water was actually fairly consistent w/ the quarter miles I timed during workouts, but I expected it to be a lot slower based on a few things: --While I tried to make sure to "sight" every so often and correct my course, I still veered away from the other swimmers and almost outside the course boundaries. --Seemed as if the shore was equally far every time I checked. Thought to myself, there can't be currents in a LAKE! But maybe if it's fed from a river or stream.... I'm not really sure about this particular lake, since it was my first swim there. A friend who did it noticed the same thing. (She's a more experienced open water swimmer and beat me on the swim...I came back on her during the run.) --Near the end of the swim, I was hitting those rusty objects (haven't a clue what they were). Found that the depth would vary, sometimes thigh deep, sometimes over my head, and so having no wish to bang myself on something that could cause tetanus (even tho my shots were up to date), I alternated wading/swimming in the last 20-30 yards (not sure abt that distance, just a guess) and took my time a bit more to be safe. Did some freestyle "sprints" (loosely defined based on my speed) during the swim (tho not at the end--felt too dangerous to swim too fast there). That might have made up some time, although I thought some of the sprints were taking me off course, despite some (probably not enough) sighting. Soooo.... what would be your strategy for swimming under these conditions. Well, besides "I wouldn't swim under those conditions." ;) Despite the problems mentioned, I actually enjoyed the race and would do it again--liked how it cooled me off so the run didn't feel as hot and muggy as it otherwise would have. Just think I have plenty of room for improvement in the swim. The run brought me up 8 places. Now let's see how I do next year.