El Dorado Reservior

El Dorado was once a famed, clear water, bass fishery that even made an appearance in Bassmaster magazine. Its flooded forests, rocky points, and flooded roads and railroads made it an ideal place for bass to thrive and 4-5lb fish were common.
Since the early 90s, the black bass population has been declining. Its decline is said to have been caused by up river agriculture causing river bank erosion and muddy water, the slow erosion of the standing timber, over fishing (at one point there was up to four tournaments a weekend and a jackpot tournament every Wednesday night), and over harvesting (the many bank fishermen the lake attracted due to good numbers of walleye, crappie, and catfish would keep every bass they caught, no matter the length).
Since then, the lake has gone through many extreme changes that have not necessarily hurt bass populations, but definitely changed the lake. El Dorado was one of the first lakes in Kansas to be inhabited by zebra mussels. At the peak of their spread, the lake gained clearity of up to 2 ft, but since then, zebra mussel population have decreased and the muddy waters have returned. Helped by the clear waters brought on by zebra mussels, smallmouth bass populations recently became prevalent in the absence of a declining largemouth population. KDWP recently introduced waterwillow to the lake and it has become fairly common since. At its height, it took an average of 5 fish for 15-20lbs to win a tournament at El Dorado Lake. Now, if you can put together a limit of 10lbs, you will win most tournaments.
Very recently, kansas's other prevalent nuisance specie, white perch, have spread to El Dorado. Their impact on black bass should be interesting. They could potentially hurt bass populations, but will almost definitely increase the population of big bass of which white perch is an ideal prey.
They have, however, hurt the lake's tournament potential. As a means of keeping white perch populations down, KDWP has increased the length limit of all black bass to 18". Good bye weigh in tournaments.

Largemouth
Population: Poor
General Size: 12-16"
Big Bass: 6lbs (people have caught 8+ lbers in the glory days)
Baits: Crankbaits, senkos, texas rig, spinnerbaits, jigs, and carolina rigs
Locations: Generally, the farther North you go, the more largemouth you catch.
Structure: Man made brush piles, flooded trees, water willow, and rip rap

Smallmouth:
Population: Fair
General Size: 10-18"
Big Bass: 5lbs (I hear about more 5lb smallies caught there than 5lb largemouths)
Baits: Lipless crankbaits, senkos, jigs, spinnerbaits, top water, shaky head, carolina rig, texas rig, tubes
Locations: The south end of the lake and anywhere with rocks.
Structure: Riprap, rocks

(I have fished this lake since 2005. Much of the information about the lake's background i got from other fishermen who fished it in its prime. If you see a discrepancy, tell me in the comments section)