earth science

Sacramento–San Joaquin

Sacramento–San Joaquin is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sacramento–San Joaquin rather than just read about it. In short: Sacramento–San Joaquin is a freshwater ecoregion in California. It includes the Sacramento and San Joaquin river systems of California's Central Valley, which converge in the inland Sacramento–San Joaquin Delta.

Key takeaways

Sacramento–San Joaquin belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sacramento–San Joaquin to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sacramento–San Joaquin from memory before moving on to harder problems.

Reference excerpt

Sacramento–San Joaquin is a freshwater ecoregion in California. It includes the Sacramento and San Joaquin river systems of California's Central Valley, which converge in the inland Sacramento–San Joaquin Delta. It also includes the mostly-closed Tulare Lake basin in the southern Central Valley, the rivers and streams that empty into San Francisco Bay, and the Pajaro and Salinas river systems of Central California which empty into Monterey Bay.

Geography The ecoregion covers an area of 176,170 square kilometres (68,020 mi2), which covers 45% of California. 99% of the ecoregion is in California, with a small portion – the Goose Lake basin – extending into southern Oregon. The Central Valley extends north and south, bounded on the east by the Sierra Nevada, and on the west by the Coast Ranges. The Sacramento River originates in the mountains ringing the northern Central Valley and flows southwards. The San Joaquin originates in the southern Sierra and flows northwards to meet the Sacramento in the inland Sacramento–San Joaquin Delta. Both are joined by tributaries flowing westward from the Sierra. In the southern Central Valley, the Kings and Kaweah River flowed from headwaters in southern Sierra to empty into shallow Tulare Lake, and the Kern River flowed into Buena Vista Lake. This basin was mostly endorheic or closed, and Tulare and Buena Vista lakes would seasonally expand with winter rains and spring runoff, and contract during the summer dry season. During periods of extreme flood the lakes would expand further and overtop the low divides separating them, and separating Tulare Lake from the San Joaquin River. San Francisco Bay occupies a gap in the Coast Ranges, and connects the Sacramento–San Joaquin Delta to the Pacific Ocean. A number of smaller rivers and creeks empty into San Francisco bay from origins in the hills and mountains ringing the bay. The Salinas River originates in the coast ranges of Central California, and flows northwards through the Salinas Valley to empty into Monterey Bay. The ecoregion also includes the Carrizo Plain, an endorheic basin in the Coast Ranges of Central California.

Fauna The ecoregion is home to 40 species of fish. These include five species of salmonids – chinook salmon (Oncorhynchus tshawytscha), pink salmon (O. gorbuscha), chum salmon (O. keta), coho salmon (O. kisutch), and steelhead (O. mykiss). These species are typically anadromous, migrating to the sea from their birthplace streams, and returning as adults to their rivers of origin to spawn. This pattern of returning to ancestral streams has given rise to distinct populations of the various species which have adaptations to their specific watersheds. Steelhead which are blocked from migrating to the sea are known as rainbow trout, and mature and breed in their native rivers. The ecoregion is also home to several distinct subspecies of rainbow trout, including the Little Kern golden trout (O. m. whitei), South Fork Kern golden trout (O. m. aguabonita), and Kern River rainbow trout (O. m. gilberti). Other anadromous native fishes include lampreys, sturgeon, and smelt. The ecoregion is home to eight endemic species, in five endemic genera - Archoplites, Pogonichthys, Orthodon, Lavinia, and Mylopharodon. Fish species endemic to the ecoregion include the Sacramento perch (Archoplites interruptus), Delta smelt (Hypomesus transpacificus), Sacramento splittail (Pogonichthys macrolepidotus), rough sculpin (Cottus asperrimus), tule perch (Hysterocarpus traskii), Sacramento pikeminnow (Ptychocheilus grandis), Kern brook lamprey (Lampetra hubbsi), and hardhead (Mylopharodon conocephalus).

Conservation and threats The Central and Salinas valleys have mostly been converted to productive agricultural regions. Many of the ecoregion's rivers have been dammed, and spring runoff is impounded and used for irrigation during the summer dry season. A portion of the Sacramento's flow is diverted to farms and cities in the southern Central Valley and Southern California. Many rivers and streams are contained in levees or have been channelized, and most of the ecoregion's floodplain wetlands, including Tulare Lake, and its riparian forests have been converted to farmland. Runoff from farms and livestock pastures carries pollutants into the rivers and streams.

Protected areas Ramsar Sites (wetlands of international importance) in the ecoregion include Elkhorn Slough on Monterey Bay, San Francisco Bay and Estuary, and Grassland Ecological Area in the San Joaquin Valley.

References

Worked examples

Example 1 — a first encounter with Sacramento–San Joaquin

Start with the simplest possible case. Write down what Sacramento–San Joaquin claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sacramento–San Joaquin before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sacramento–San Joaquin ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sacramento–San Joaquin

In research: Sacramento–San Joaquin appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sacramento–San Joaquin in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sacramento–San Joaquin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Drainage basins of the Pacific Ocean, Ecoregions of California, Freshwater ecoregions, so understanding it makes those chapters shorter.
In everyday life: Look for Sacramento–San Joaquin outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Sacramento–San Joaquin” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Sacramento–San Joaquin in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sacramento–San Joaquin means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sacramento–San Joaquin out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sacramento–San Joaquin in simple terms?

Why does Sacramento–San Joaquin matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sacramento–San Joaquin?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sacramento–San Joaquin.