San Lorenzo Creek facts for kids

San Lorenzo Creek (which means Arroyo de San Lorenzo in Spanish) is a cool, natural stream about 10.7 miles (17.2 km) long. It flows all year round! This creek winds its way through Hayward, California, and nearby towns. It eventually empties into the huge San Francisco Bay. You can find its mouth at the Hayward Regional Shoreline.

The creek and trees in downtown Hayward.

A view of San Lorenzo Creek from a bridge in downtown Hayward.

The sign for the San Lorenzo Creek Trail.

Where Does San Lorenzo Creek Flow?

The San Lorenzo Creek starts in Castro Valley. It is the main waterway in the San Lorenzo Watershed. A watershed is an area of land where all the water drains into one main river or creek.

• A creek called Sulphur Creek used to flow on its own.
• But in the 1960s, most of its water was sent into San Lorenzo Creek. This was done to help stop floods in downtown Hayward.
• Now, Sulphur Creek only flows into the Bay on its old path when there's a lot of rain.

The creek runs through the city of Hayward. It also goes through the communities of Cherryland, Ashland, and San Lorenzo. Finally, it flows into San Francisco Bay. Part of the San Francisco Bay Trail runs right along the creek's mouth.

Two reservoirs, Cull Canyon and Don Castro, also feed into the creek. These reservoirs are part of regional parks.

History of the Creek

San Lorenzo Creek has an interesting history! It was an important spot for early explorers.

• In 1769–70, the Portolá expedition explored this area.
• Their scouts camped at the creek. This was the farthest north they went before turning back.
• Later, in 1770 and 1772, other explorations led by Pedro Fages also used this camp.

The creek had different names long ago.

• Records from 1772 show Spanish colonists called it "Arroyo de San Salvador de Horta."
• They also called it "Arroyo de la Harina."
• The name "Arroyo de San Lorenzo" has been used since at least 1812. It was written this way in land grants from 1841 and 1842.

An old road called El Camino Viejo (now Mission Boulevard) crossed San Lorenzo Creek. It crossed where Mission Boulevard crosses it today in San Lorenzo, California.

Wildlife and Nature

San Lorenzo Creek used to be home to amazing fish!

• It supported steelhead, which are a type of rainbow trout.
• Steelhead are anadromous. This means they are born in fresh water, live in the ocean, and then return to fresh water to lay their eggs.
• Other types of salmon fish also lived here.

However, things changed as more cities grew around the creek.

• A study in 1997 found no young or adult steelhead in the creek.
• This was because of city growth and dams, which affected the creek's environment.

Since 1997, steelhead in the Bay Area have been listed as a threatened species. This means they are at risk of disappearing.

• Many groups and government agencies are now working together.
• They are trying to restore the creek's habitat.
• Their goal is to help migratory fish from the Bay reach places in the creek where they can lay their eggs.