The Laguna Creek watershed runs through the heart of Fremont.  The watershed is fed by run-off during our winter and spring storms and by natural springs along the foothills of Mission Peak.  Several  creeks, such as Vargas and Morrison Creek, feed into Mission as it flows alongside Lake Elizabeth and nourishes Stivers Lagoon.  The water then flows via Irvington and Laguna Creeks into Mud Slough, and then into the San Francisco Bay.

Mud Slough is affected by tidal action, which has created a brackish environment for birds and mammals who rely on a rich diversity of other organisms.  The abundance of food supports a wide variety of vegetation and wildlife.  The flora  and fauna change from brackish to marine as you head towards the San Francisco Bay.

The impact on Mud Slough from development in the area adjacent to the slough has been significant.  Due to its close proximity to the San Francisco Bay, its habitat is unique.  Salt evaporators are present on one side and industrial parks on the other, as the slough meanders into the larger Coyote Creek.  It then empties into the San Francisco Bay.

In the geologic past, a once mighty river flowed through this area. Large animals such as mammoths, sabercats, sloths, and camels enjoyed the rich habitat during the Pleistocene. The changing landscape, caused by movement along the Hayward fault, interrupted the major river flow and created a series of creeks.  For thousands of years, Mud Slough was a fertile habitat, teeming with wildlife, including grizzly bear, elk and beaver. Many fish and bird species abounded. The animals that lived in the slough and the surrounding habitat found food and shelter.

Native people, including the Ohlone Indians, used  Mud Slough as a road to the Mission area especially for hunting and gathering food from the San Francisco Bay. Even the early Spanish explorers would bring small boats up Mud Slough to access the lush hunting in the surrounding wetlands. As more humans moved into the area, it was an easy place to dispose of garbage and sewage. Prior to 1970, the value of the wetlands was not understood, so human activities destroyed the very habitat that attracted them in the first place.

As the population grew, changes in the traditional land use occurred.. The need for salt throughout the west was an opportunity for local companies to create salt ponds. Dikes were formed and large evaporative ponds were created, as much of the lower San Francisco Bay was used to harvest salt for use in western United States. As the wetlands were destroyed, inexpensive land became available and many industrial parks were created, which brought jobs and commerce to the area.

Tidal currents in the San Francisco Bay send   garbage from the south bay towards the slough which in turn drifts in on the incoming tides. Debris also flows downstream from Laguna and     Irvington Creeks. We can prevent some of this pollution by    keeping the creeks above the Slough as clean as possible, and enforcing  existing     pollution ordinances. We can be vigilant and contact the appropriate agencies when we see problems  occurring. Mud Slough needs to be revitalized by restoring habitat.