Browse Map

Explore away

Explore Map Collection

Check out our basemaps

Print a Map Plus

Generate a high-quality PDF

Field Guide

Discover local flora, fauna, geology, and more

Local Flora & Fauna

Learn the ecology of your area

Local Geology

Learn the geologic formation at your feet

Get Started or Sign In

Welcome

Continue with Apple

Already have an account? Sign In

MAP

Topo

Measure

Topo

Ecoregions

Public Lands

...

BASEMAPS

Default Weather

Temperature

Smoke

...

WEATHER

Delta

Ecoregion in Central Valley, CA

Print Map

Generate High-Quality PDF

The Delta ecoregion is a low elevation area, near sea level, at the confluence of major rivers. It is characterized by numerous sloughs and channels formed where the Sacramento, San Joaquin, Cosumnes, Mokelumne, and Calaveras Rivers enter the ecoregion. Water from these rivers commingles in the Delta and is influenced by tidal action, streamflow, and water diversion as it flows toward San Francisco Bay. Brackish tidal water enters the area when river flow is low during the summer and autumn. In the main part of the region, former wetland islands have been reclaimed for intensive agriculture with a network of levees. Corn, alfalfa, hay, and wheat are the most extensive crops on these organic soils, although various crops were grown historically. Soil temperature regimes are thermic and soil moisture regimes are mostly aquic, with some xeric on levees. Land subsidence and salinity intrusion are two of many important resource issues here. The western part of the ecoregion includes areas of brackish and seasonally freshwater marshes and wetlands that surround Grizzly Bay and Suisun Bay. The native vegetation historically consisted of aquatic plants such as tules, cattails, and rushes. Saltgrass was dominant in many areas. Many of the diked wetlands are managed for waterfowl hunting. The Delta plays a central role in the distribution of water from the State’s wetter northern regions to its southern, arid, and populous cities and agricultural areas. These water diversions can have adverse effects on species such as delta smelt, Chinook salmon, Central Valley steelhead, and green sturgeon.

— EPA

Taxonomy

Classified As

Ecoregion