all lakes go down hill as they age for the most part . smaller spots silt in and even larger lakes do as well . cover deteriorates and fish populations follow trends in habitat .
some lakes may remain good for very long periods of time though and some not so much . natural alkalinity levels and things that mother nature comes up with are contributing factors as well .
the good news is that white crappie love a good ole mud hole and thrive in them ,so not all is lost ....LOL