In spite of its less than fragrant aroma, communities flourished on the marshy lands around the channel-the villages of Clinton and San Antonio on its eastern shore, and the town of Oakland on the west. The only east-west access was across the slough, so in 1853 Carpentier built a bridge at Twelfth Street, across the outlet to the estuary, charging (and pocketing) a toll.

But it was 1868 that ushered in the first human induced change to the waterway's hydrology, when Samuel Merritt, Oakland mayor and slough side property owner, quite literally turned the tide on the slough's declining appeal, and changing its character forever. Merritt proposed, spearheaded, and when he found support lacking-personally funded construction of a dam at the Twelfth Street bridge that would control the tidal rise and fall through the inlet. This, he reasoned, would transform the slough from mud flat to lake, from a sewer to a source of civic pride. It didn't take long for Merritt's vision to become reality. San Antonio slough became Lake Merritt, the nation’s largest body of salt water within a city limit.

At that time Lake Merritt still retained its fringing wetlands. Its thickly matted margins teemed with migratory wildfowl and a corresponding bird hunting contingent who, in the newly possessive light in which the townsfolk now viewed the lake, began to seem more like poachers. Town leaders supported Merritt in his proposal for a wildlife refuge to cut the gunplay and protect the large flocks of migrating waterfowl for which the area was vital winter habitat. There's little doubt that Merritt's motives were selfserving, but the outcome was both beneficent and precedent setting. Things happened swiftly. Merritt used his influence, and in 1870 the state legislature voted the Lake Merritt Wildlife Refuge into being, creating what would be the very first, legally established public wildlife sanctuary in North America. The change in status made it unlawful to take or kill fish-except by hook and line and prohibited taking birds for game.

There was, however, no provision made to protect the lake's surrounding marshes, and these began to shrink under the pressure of development. The property around the lake qualified, by this time, as prime real estate. Residences soon dotted its muddy shores, and in spite of the inlet's newfound popularity, the water quality continued to deteriorate. Two sewer systems were undertaken in 1868, the year Merritt had proposed the dam, but these weren't finished until 1875. The battle with contamination continued for decades. Then, too, there was a certain natural reality. A mud flat is a mud flat. The "lake" kept silting up.