119-615: The Holland Tract is an island in the Sacramento–San Joaquin River Delta . It is part of Contra Costa County , California , and managed by Reclamation District 2025. Its coordinates are 37°59′55″N 121°36′08″W / 37.99861°N 121.60222°W / 37.99861; -121.60222 ( Holland Tract ) , and the United States Geological Survey measured its elevation as 7 ft (2.1 m) in 1981. It appears on
238-711: A 1952 United States Geological Survey map of the area. Most of the island is owned by the Metropolitan Water District of Southern California . This Contra Costa County, California –related article is a stub . You can help Misplaced Pages by expanding it . Sacramento%E2%80%93San Joaquin River Delta The Sacramento–San Joaquin River Delta , or California Delta , is an expansive inland river delta and estuary in Northern California . The delta
357-591: A 62 percent chance of occurring in the next two decades if subsidence isn’t addressed." Simultaneous levee failures on the Delta's 57 islands in the wake of an earthquake which allow the inflow of brackish San Francisco Bay waters could threaten the water supply for the Central Valley , which includes both the irrigation water for its $ 17 billion agricultural economy and the drinking water for about 25 million people. About 500 plant and animal species inhabit
476-470: A challenge to the agricultural community to eliminate. The plants spread by budding and spreading its seeds, and those seeds fall to the bottom of the water, where they can stay viable in the muck for years. The Hyacinth can form a mat up to 6 feet (1.8 m) thick, shutting off light and becoming acidic when they decompose. The Delta was formerly populated by large herds of deer and tule elk ; their trails were so vast that early Spanish explorers supposed
595-485: A chance to learn about the disaster that represented the largest domestic loss of life in the U.S. in World War II, and the impact it had on race relations in the U.S. military. Brannan Island State Recreation Area offers boat launches and facilities that support fishing, windsurfing, waterskiing, and sailing, in addition to campsites, picnic areas and trails to allow visitors to explore the marshes and islands of
714-424: A concrete-lined and fenced irrigation canal still makes a loop through central county and provided industrial and agricultural grade water to farms and industry. While no longer used for extensive irrigation, it is still possible for adjoining landowners (now large suburban lot owners) to obtain pumping permits. Most of this water is destined for the heavy industry near Martinez. As with the railroad rights of way there
833-573: A non-Indian population of over 100,000. The number of Indians living in California in 1850 has been estimated to be from 60,000 to 100,000. By 1850 the Mission Indian populations had largely succumbed to disease and abuse and only numbered a few thousand. California's 1852 state Census gives 31,266 Indian residents, but this is an under-count since there was little incentive and much difficulty in getting it more correct. Contra Costa County
952-422: A north–south route for migratory birds, crosses the Delta. The migratory birds provide both birdwatching and hunting opportunities. Including the northern Suisun Marsh , there are over 150 private duck clubs in the area. The levee system allowed farmers to drain and reclaim almost 500,000 acres (780 sq mi; 2,000 km ) of the Delta, then a tidal marsh. Once the rivers were confined to their riverbeds,
1071-460: A once substantial integrated steel plant, United States Steel , now reduced to secondary production of strip sheet and wire. The San Joaquin River forms a continuation of the northern boundary turns southward to form the eastern boundary of the county. Some substantial Sacramento-San Joaquin Delta "islands" (actually leveed former marshes) are included in this corner of the county. The West County
1190-401: A result the Delta is most susceptible to salinity intrusion between February and June. However, regulation provided by dams helps boost freshwater flows during dry summers and autumns, reducing the risk of salinity intrusion in these months. Diversions located at the southern end of the Delta, however, have negated some of the benefits of upstream dams. The powerful pumps that supply water for
1309-510: A risk for human consumption as well. After numerous rounds of mitigation following the 2005 Smelt Biological Opinion (BiOp) lead to pumping restrictions from the State and Federal projects from the Delta, a number of potential solutions to the Delta's problems have been proposed. These followed the CALFED process which had offered several staged solutions. A first set of alternatives would maintain
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#17327795008931428-421: A threat that has the potential to impact human life. Several types of toxic cyanobacteria have appeared in the Delta, with Microcystis aeruginosa being one of the most common types. Microcystis aeruginosa produce microcystins which are hepatotoxins that can cause liver cancer. Frequent Microcystis blooms have impacted the food web of the Delta at multiple trophic levels . Microcystis spp. blooms in
1547-674: A whole regiment in there for several days, and some who ventured in just disappeared." Marc Reisner , A Dangerous Place (2003) The Delta was formerly located at the bottom of a large inland sea in the Central Valley, which formed as the uplift of the California Coast Ranges blocked off drainage from the Sierra Nevada to the Pacific. About 560,000 years ago, water breached the mountains, carving out
1666-573: Is a county located in the U.S. state of California , in the East Bay of the San Francisco Bay Area . As of the 2020 United States Census , the population was 1,165,927. The county seat is Martinez . It occupies the northern portion of the East Bay region of the San Francisco Bay Area and is primarily suburban . The county's name refers to its position on the other side of the bay from San Francisco . Contra Costa County
1785-515: Is a 58.3% registration advantage with 641 Republicans (6.1%) out of 10,550 registered voters compared to 6,793 Democrats (64.4%) and 2,746 voters who have no party preference (26.0%). The following table includes the number of incidents reported and the rate per 1,000 persons for each type of offense. The great rancheros of the Spanish period were divided and sold for agricultural uses, with intensively irrigated farming made possible in some areas by
1904-435: Is also provided for wildlife refuges and habitat conservation works. The Contra Costa Canal and North Bay Aqueduct also take Delta water, supplying the nearby San Francisco Bay Area. Locally, the Delta provides water for cities and towns in five counties and for over 1,800 agricultural users. The Delta is also a popular site for recreation and is used for sailing, waterskiing, houseboating, fishing, and hunting. The Delta
2023-642: Is formed at the western edge of the Central Valley by the confluence of the Sacramento and San Joaquin rivers and lies just east of where the rivers enter Suisun Bay , which flows into San Francisco Bay , then the Pacific Ocean via San Pablo Bay . The Delta is recognized for protection by the California Bays and Estuaries Policy . Sacramento–San Joaquin Delta was designated a National Heritage Area on March 12, 2019. The city of Stockton
2142-579: Is home to over 100 marinas and 25 yacht clubs. In 2010, over seven million 'annual visitor boating days' occurred on the Delta, according to a local government survey. The Delta is home to several state and regional parks, reflecting a variety of recreational activities. These include historical interpretative centers, including Delta Meadows and Locke Boarding House and the Old Sacramento State Historic Park . The Port Chicago Naval Magazine National Memorial offers visitors
2261-475: Is in the cities of Richmond , where there is a 60.3% registration advantage with 3,192 Republicans (6.2%) out of 51,395 registered voters compared to 34,159 Democrats (66.5%) and 12,095 voters who have no party preference (23.5%); El Cerrito , where there is a 59.0% registration advantage with 1,169 Republicans (7.4%) out of 15,877 registered voters compared to 10,543 Democrats (67.6%) and 3,654 voters who have no party preference (23.0%); and San Pablo , where there
2380-629: Is included in the San Francisco–Oakland–Berkeley, CA Metropolitan Statistical Area . In prehistoric times, particularly the Miocene epoch , portions of the landforms now in the area (then marshy and grassy savanna ) were populated by a wide range of now extinct mammals , known in modern times by the fossil remains excavated in the southern part of the county. In the northern part of the county, significant coal and sand deposits were formed in even earlier geologic eras . Other areas of
2499-627: Is land and 88 square miles (230 km ) (11%) is water. Contra Costa County's physical geography is dominated by the bayside alluvial plain, the Oakland Hills – Berkeley Hills , several inland valleys, and Mount Diablo , an isolated 3,849-foot (1,173 m) upthrust peak at the north end of the Diablo Range of hills. The summit of Mount Diablo is the origin of the Mount Diablo Meridian and Base Line , on which
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#17327795008932618-537: Is located on the San Joaquin River at the eastern edge of the delta. The total area of the Delta, including both land and water, is about 1,100 square miles (2,800 km ). Its population is around 500,000. The Delta was formed by rising sea level following glaciation, leading to the accumulation of Sacramento and San Joaquin River sediments behind the Carquinez Strait , the sole outlet from
2737-430: Is now Concord/Buchanan Field Airport . Additionally, a large Naval Weapons Depot and munitions ship loading facilities at Port Chicago remain active to this day, but with the inland storage facilities recently declared surplus, extensive redevelopment is being planned for this last large central-county tract. The loading docks were the site of a devastating explosion in 1944. Port Chicago was bought out and demolished by
2856-446: Is now an extensive public trail system along these canals. The development of commuter railroads proceeded together with the subdivision of farms into parcels. In some cases, such as the development of Saranap , the same developer controlled both the railroad ( Sacramento Northern ) and the development. These early suburbanization developments were an extension of the earlier development of trolley car suburbs in what are now considered
2975-422: Is now relatively robust but should be improved to effectively eliminate the risk of failure in extreme floods and earthquakes. It emphasizes the significant value of the infrastructure that passes through the Delta, including water conveyance, in addition to life and property, and the value of the Delta as a Place. A 2019 article states that "a catastrophic levee failure, defined as 20 islands flooding at once, has
3094-588: Is required again. Delta waterways are also major transportation corridors for agricultural products; the ports of Sacramento and Stockton , located on the Sacramento and San Joaquin rivers, respectively, are the most important inland ports in California. The San Joaquin River throughout most of the Delta and the lower Sacramento River below its connection to the Sacramento Deep Water Ship Channel are routinely dredged to allow
3213-729: Is shipped to both the Benicia Refinery and the Martinez Refinery by water. Nearby is the Port Chicago Marine Ocean Terminal , a facility that supports the U.S. Navy. The Delta is often considered the nexus of California's statewide water system . About half the total river flow in the state passes through this region, from which water is exported to other areas of the San Joaquin Valley, Southern California and portions of
3332-416: Is the area near or on San Francisco and San Pablo bays. The housing stock in the region was extensively developed after the great San Francisco earthquake of 1906. Much of the housing stock in these areas is becoming quite expensive. As an alternative to moving to either the expensive central county, or the too-distant East County, this area is becoming gentrified , with a mix of races and income levels —
3451-400: Is used as a sedimentation enhancing strategy to reduce subsidence and restore the wetlands in the Delta. Land subsidence has endangered the Delta's system of protective levees, occasionally triggering levee failure and subsequent flooding. Using the Delta as the primary valve in a linear water system may have been convenient for a period, but that convenience has come at a high price for
3570-536: The Bay Area Rapid Transit (BART) system, the modernization of Highway 24 , and the addition of a fourth Caldecott Tunnel bore all served to reinforce the demographic and economic trends in the Diablo Valley area, with cities such as Walnut Creek and Concord becoming edge cities . The central county cities have in turn spawned their own suburbs within the county, extending east along
3689-466: The Diablo thrust fault near Danville are all considered capable of significantly destructive earthquakes and many lesser related faults are present in the area that cross critical infrastructure such as water, natural gas, and petroleum product pipelines, roads, highways, railroads, and BART rail transit. Contra Costa County is broadly divided into three sub-areas: The most notable natural landmark in
Holland Tract - Misplaced Pages Continue
3808-716: The Mexican War of Independence resulted in the secularization of the missions with the re-distribution of their lands, and a new system of land grants under the Mexican Federal Law of 1824. Mission lands extended throughout the Bay Area, including portions of Contra Costa County. Between 1836 and 1846, during the era when California was a province of independent Mexico, the following 15 land grants were made in Contra Costa County. The smallest unit
3927-614: The San Ramon Valley . Early contact was fleeting and mostly peaceful, however, in the late 1700s, Spanish cattle were grazed the territory of the Saklan and their neighbors. The Saklans were one of the few groups who mounted resistance against the efforts of the Spanish to convert them to Christianity. Christian natives were sent to the Saklans to convince them to give up their culture and come to Mission San Jose; they were killed by
4046-551: The surveys of much of California and western Nevada are based. The Hayward Fault Zone runs through the western portion of the county, from Kensington to Richmond. The Calaveras Fault runs in the south-central portion of the county, from Alamo to San Ramon. The Concord Fault runs through part of Concord and Pacheco, and the Clayton-Marsh Creek-Greenville Fault runs from Clayton at its north end to near Livermore. These strike-slip faults and
4165-598: The Arkansas or Swampland Act , which allowed for the transfer of title for wetlands to private owners on the conditions that the land would be reclaimed. In California, more than two million acres (3,100 sq mi; 8,100 km ) of wetlands were partitioned under the Swampland Act, of which 500,000 acres (780 sq mi; 2,000 km ) were in the Sacramento–San Joaquin Delta, roughly
4284-681: The Bay area to supply some 1,130,000 acres (1,770 sq mi; 4,600 km ) of farmland and 23 million people in central and Southern California. The Delta provides an estimated seven million acre-feet (2.1 cu mi; 8.6 km ) of water per year, of which about 100,000 acre-feet (0.030 cu mi; 0.12 km ) are exported to the San Francisco Bay Area, 1.7 million acre-feet (0.50 cu mi; 2.1 km ) are used locally, and over five million acre-feet (1.5 cu mi; 6.2 km ) are exported to
4403-606: The Catholic Church (with 204,070 members) and The Baptist General Conference (with 24,803 members). The Rohr Jewish Learning Institute teaches courses in the county. Since 1932, Contra Costa County has been a Democratic stronghold in presidential elections. It temporarily leaned toward the Republican Party in the 1970s and 1980s, with successive presidential wins by Richard Nixon in 1972, Gerald Ford in 1976, and Ronald Reagan in 1980 and 1984. Reagan
4522-491: The Central Valley Project and State Water Project cause water in the Delta to flow from north to south instead of the natural direction of east to west. This has caused multiple environmental issues, such as the disruption of fish migration and salinity buildup in the eastern Delta, where salts can no longer be flushed to the sea by natural river flows. Since 1900, there have been over 160 levee failures in
4641-569: The Central Valley to San Pablo Bay. The narrowness of the Carquinez Strait coupled with tidal action has caused the sediment to pile up, forming expansive islands. Geologically, the Delta has existed for about 10,000 years, since the end of the Last Glacial Period . In its natural state, the Delta was a large freshwater marsh , consisting of many shallow channels and sloughs surrounding low islands of peat and tule . Since
4760-466: The Central Valley; the combination of the narrow strait and tidal action pushing inland dramatically slowed the current of these rivers and forced them to drop sediment. The early delta was composed of shifting channels, sand dunes, alluvial fans and floodplains that underwent constant fluctuation because of rapidly rising seas – one inch (25 mm) per year. About 8,000 years ago, the rate of sea-level rise slackened, allowing wetland plants to take hold in
4879-472: The Delta area is urban and 117 sq mi (300 km ) are undeveloped land. The rivers, streams, sloughs and waterways of the Delta total about 95 sq mi (250 km ) of surface, although this fluctuates greatly with seasons and tides. Geologically, it is not considered a true river delta, but rather an inverted river delta , as it formed inward (sediments accumulating progressively inland) rather than outward. The only other major river delta in
Holland Tract - Misplaced Pages Continue
4998-449: The Delta can be attributed to a variety of factors with the most important being lowered streamflow . From 2004 through 2008 researchers collected different water quality parameters during the cyanobacteria blooms and determined that the blooms appeared after reaching a threshold of 19 °C (66 °F) which was exacerbated by reduced precipitation , reduced streamflow, and increased nutrient concentrations. They also determined that
5117-401: The Delta cannot be irrigated using conventional methods due to the highly absorbent quality of the peat soil and irregularities caused by land subsidence. Irrigation is typically carried out periodically by piping water into small "spud ditches", which spread water over large areas and raise the local water table . The heightened groundwater is then gradually depleted by the crop until irrigation
5236-507: The Delta each year – about 50 percent of all California's runoff. Nearby cities include Lodi and Stockton to the east, Tracy and Manteca to the south, Brentwood to the southwest, and Pittsburg and Antioch to the west. The state capital, Sacramento , is located just to the north of the Delta. The Sacramento River Deep Water Ship Channel connects the Delta to the Port of Sacramento , with its terminus located near Rio Vista , on
5355-477: The Delta flooded for up to two hours each day at high tide; during spring tides or river floods, it was not uncommon for the entire Delta to be under water. Humans have inhabited the Delta for up to 4,300 years. The estimated indigenous population of the Delta at the time of first contact with Europeans was about 3,000–15,000, predominantly Miwok and Maidu , with some estimates ranging up to 20,000. The Native Americans lived in villages of 200–1,000 people on
5474-490: The Delta from the summit of nearby Mount Diablo . For decades, the Delta was little utilized by the Spanish colonists. Expeditions from 1806 to 1812 failed to locate suitable mission sites in the Delta area. However, frequent military expeditions were made into the Delta from 1813 to 1845 in response to animosities between the Native Americans and the Spanish and later Mexicans; also several land grants were made in
5593-435: The Delta in its current condition and configuration. The second would restore parts of the Delta more closely to its natural state but include the construction of an additional Peripheral Canal to maintain the water supply currently provided by the Delta. Contra Costa County, California Contra Costa County ( / ˌ k ɒ n t r ə ˈ k ɒ s t ə / ; Contra Costa , Spanish for 'Opposite Coast')
5712-558: The Delta lies at the foothills of the California Coast Ranges , while to the northwest sit the lower Montezuma Hills . Most of the Delta lies within Contra Costa , Sacramento , San Joaquin , Solano and Yolo Counties. The total human population of the Delta was 515,264 as of 2000. Altogether, the Delta covers 1,153 square miles (2,990 km ), with 841 sq mi (2,180 km ), or nearly 73 percent, devoted to agriculture. About 100 sq mi (260 km ) of
5831-513: The Delta were found to decrease the diversity of the aquatic microbial community. Additionally, the cyanobacteria blooms in the Delta have led to decreased zooplankton mass and density . There is also concern for further spread throughout the food web via bioaccumulation . Microcystins were detected in the tissue of clams at levels much higher than the ambient water around them because of microcystin's ability to covalently bind to tissue. The increased occurrences of cyanobacteria blooms in
5950-478: The Delta's ecosystem. Delta fish populations have been significantly reduced due to the reclamation of marshland and diversions of fresh water. In 2004, the Delta smelt was found to be on the edge of extinction. The survival of the Delta smelt has been one of the largest environmental issues in California, as environmental measures enacted to protect its population have often reduced the amount of water available for federal water projects that depend on water pumped from
6069-433: The Delta, trapping sediment; the growth and decay of these plants began to form the vast peat deposits that make up the Delta islands. The Delta reached a stabilized form similar to its mid-1800s state about 2,000–3,000 years ago. Immediately before large-scale human development, most of the Delta islands had saucer-like cross sections, with low natural levees flanking a marshy interior "bowl" that flooded intermittently with
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#17327795008936188-419: The Delta, which is one of the largest estuaries in western North America. Before agricultural development of the Delta region, the Delta's many islands were forested by Tule , bulrush , and various reeds that flourished in intermittently flooded, low-lying marshy areas. Over thousands of years, the growth and decay of the various swampland plants formed a layer of peat 50 feet (15 m) deep in places, hence
6307-582: The Delta. A 2010 study shows that the anglers in the Delta who ate these fish had higher levels of mercury in their system. Delta fish have also been found to have high levels of a toxin called methylmercury which originates from old gold rush era mines in the Sierras. In that same study, it was found that women along the delta were consuming high numbers of fish, making them more susceptible to poisoning. Nutria were found in Merced County in 2017 on
6426-879: The Federal Government to form a safety zone near the Naval Weapons Station loading docks. At one time the Atlas Powder Company (subsequently closed) produced gunpowder and dynamite. The site of the former Atlas Powder Company is located at Point Pinole Regional Shoreline , part of the East Bay Regional Parks District . With the postwar baby boom and the desire for suburban living, large tract housing developers would purchase large central county farmsteads and develop them with roads, utilities and housing. Once mostly rural walnut orchards and cattle ranches,
6545-520: The Sacramento–San Joaquin Delta. The California Office of Environmental Health Hazard Assessment has issued a safe eating advisory for any fish caught in Central and South parts of the Delta due to elevated levels of mercury and PCBs. In addition, there is a notice of "DO NOT EAT" for any fish or shellfish from the Port of Stockton . There is a separate safe eating advisory for the Northern part of
6664-541: The Sacramento–San Joaquin River Delta. These numbers include multiple failures of a single levee structure. Levee failures, also known as breaches, can be caused by overtopping or structural failure . One of the most recent examples of levee failure in the Sacramento–San Joaquin River Delta occurred in June 2004 when a levee breach caused more than 150,000 acre-feet (190,000,000 m ) of water to flood
6783-438: The Saklans who wanted nothing to do with the Spanish way of life. A punitive expedition was sent to the area in 1797 to repress the Saklans, and a battle was fought in modern-day Lafayette. In the early 1800s, many Saklan fled to the mission as a result of societal collapse from disease. By the 1810s the Saklan's tribal range was essentially devoid of inhabitants. Early interaction of these Native Americans with Europeans came with
6902-467: The San Joaquin Valley, coastal Central and Southern California. Intrusion of brackish water into the Delta is a recurring natural phenomenon; however, it became a serious issue after the development of agriculture in the upper Sacramento and San Joaquin valley reduced inflows. Multiple droughts between 1910 and 1940 caused significant salinity intrusion in the Delta because of the reduction of freshwater inflows. The growing Delta water quality issue provided
7021-611: The Spanish colonization via the establishment of missions in this area, with the missions in San Jose, Sonoma, and San Francisco and particularly the establishment of a Presidio (a military establishment) in 1776. Although there were no missions established within this county, Spanish influence here was direct and extensive, through the establishment of land grants from the King of Spain to favored settlers. In 1821 Mexico gained independence from Spain. While little changed in ranchero life,
7140-409: The area was first developed as low-cost, large-lot suburbs, with a typical low-cost home being placed on a "quarter-acre" (1,000 m ) lot — actually a little less at 10,000 square feet (930 square metres). Some of the expansion of these suburban areas was clearly attributable to white flight from decaying areas of Alameda County and the consolidated city-county of San Francisco , but much
7259-614: The area was inhabited by cattle. Significant numbers of California grizzly bears could also be found in the Delta. The extensive wetlands of the Delta supported massive bird populations, half the migrating waterfowl in California continue to pass through the Delta. A survey in 2012 recorded a spring duck population of 48.6 million, the highest since counts began in 1955. Large mammals in the Delta have not fared so well; with most of their habitat converted to agriculture, remaining populations were highly susceptible to human impacts and natural disasters. Grizzlies were hunted to extinction, while
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#17327795008937378-449: The area. Originally a Delta farming island, Franks Tract flooded in 1936 and again in 1938. The levees were never repaired and the island remained submerged, becoming an expanse of open water dotted with remnants of the original levees now the only landforms. In 1959, the area became a state park. Franks Tract State Recreation Area is accessible only by water and is used for fishing, waterfowl hunting, and boating. The Pacific Flyway ,
7497-474: The bayside portions opposite San Francisco and northern portions of Santa Clara County , were given up to form Alameda County effective March 25, 1853. The land titles in Contra Costa County may be traced to multiple subdivisions of a few original land grants. The grantee's family names live on in a few city and town names such as Martinez , Pacheco and Moraga and in the names of streets, residential subdivisions, and business parks. A few mansions from
7616-504: The conditions are met Microcystis have the ability to dominate the lower trophic levels hence why they are able to bloom. Additionally, when microcystins are present in the system then the consumers in the food web are at risk due to the effects of bioaccumulation. Fish that are present and active during cyanobacteria blooms can often have microcystin levels high enough to produce sublethal effects. Because microcystins can concentrate inside fish at multiple trophic levels it also represents
7735-577: The construction of a house within a year. Fences were not required and were forbidden where they might interfere with roads or trails. Locally a large family required roughly 2000 head of cattle and two square leagues of land (fourteen square miles) to live comfortably. Foreign entrepreneurs came to the area to provide goods that Mexico could not, and trading ships were taxed. The exclusive land ownership in California by Hispanics in California would soon end. John Marsh , owner of Rancho Los Meganos in Contra Costa County, sent letters to influential people in
7854-409: The county have ridges exposing ancient but intact (not fossilized) seashells, embedded in sandstone layers alternating with limestone . Layers of volcanic ash ejected from geologically recent but now extinct volcanoes , compacted and now tilted by compressive forces, may be seen at the site of some road excavations. This county is an agglomeration of several distinct geologic terranes , as is most of
7973-482: The county is the 3,849-foot (1,173 m) Mount Diablo , at the northerly end of the Diablo Range . Mount Diablo and its neighboring North Peak are the centerpiece of Mt. Diablo State Park (MDSP), created legislatively in 1921 and rededicated in 1931 after land acquisitions had been completed. At the time this park comprised a very small portion of the mountain. In the 1960s, suburban development expanding from
8092-464: The county's estuarine north shore; with the older development areas of Bay Point and Pittsburg being augmented by extensive development in Antioch , Oakley , and Brentwood . The effects of the housing value crash (2008–2011) varied widely throughout the county. Values of houses in prosperous areas with good schools declined only modestly in value, while houses recently built in outlying suburbs in
8211-412: The development of canals that brought water from the eastern riverside portions of the county to the central portion. Other areas could use the more limited water available from local creeks and from wells. Orchards dominated where such water was available, while other, seasonally dry areas were used for cattle ranching. In central parts of the county walnuts were an especially attractive orchard crop, using
8330-524: The eastern United States extolling the climate, soil, and potential for agriculture in California, with the purpose of encouraging Americans to immigrate to California and lead to its becoming part of the United States. His letters were published in newspapers throughout the East which started the first wagon trains to California. He invited the settlers to stay on his ranch , and Rancho Los Meganos became
8449-454: The eastern edge of the Delta, where the land was higher and less susceptible to flooding. Their lives centered around the abundant reeds or tules that grew on the Delta islands, which they used to make houses, boats, and garments. Staple foods included tule roots and pollen, acorns, wild fruits and seeds, fish and game. Europeans first entered the Delta region in 1772, when Spanish explorer Don Pedro Fages and missionary Juan Crespí observed
8568-467: The eastern part of the county experienced severe reductions in value, accelerated by high unemployment and consequent mortgage foreclosures, owner strategic walk-aways , and the too-rapid conversion of neighborhoods from owner-occupancy to rentals. Home values rebounded as the economy recovered from the recession. According to the U.S. Census Bureau , the county has a total area of 804 square miles (2,080 km ), of which 716 square miles (1,850 km )
8687-480: The edge of the Delta. State officials are concerned that they will harm the infrastructure that sends water to San Joaquin Valley farms and urban areas. The Delta has seen numerous cyanobacteria blooms with increasing frequency over the past two decades. Cyanobacteria have the potential to produce cyanotoxins which can pose a risk to humans and animals upon contact. Because of this cyanobacteria blooms are seen as
8806-565: The entire island of Jones Tract . But, the significant improvements made to the Delta levee system since 1982 have reduced the incidence of failures to this one major failure in 30 years. The most up-to-date description and discussion of the Delta levee system can be found in the Economic Sustainability Plan of the Delta Protection Commission. This study concluded that the Delta levee system
8925-436: The entirety of Sherman Island, some 14,000 acres (22 sq mi; 57 km ), was diked and drained by a system of levees, flumes and floodgates. By the 1890s, the original levee system had been largely replaced with stronger embankments consisting of clay dredged from nearby river bottoms. By 1900, about 235,000 acres (367 sq mi; 950 km ), or nearly half of the Delta's land area, had been reclaimed. Most of
9044-410: The environment. —Paul Shigley, The Devil Is in the Delta (2012) Land subsidence also allows brackish water intrusion into the Delta, an issue compounded by the diversion of up to 25% of the freshwater flowing into the Delta. The decreased volume of freshwater in the Delta has had a profound effect on its ecology. In most years, large dams in the Delta watershed fully hold back spring runoff; as
9163-439: The existing Delta infrastructure, forcing landowners to rebuild their levees higher and stronger; more flooding in 1878 and 1881 reinforced these notions. Although land holdings in the Delta were initially limited to 320 acres (0.50 sq mi; 1.3 km ) per buyer, this limit was repealed in 1868, allowing large agricultural conglomerates to take entire islands and carry out massive reclamation projects. From 1868 to 1869,
9282-533: The extremely high fertility of Delta soils. Sediment deposits formed natural levees around the borders of islands, where larger trees, mainly willows, were able to take root and form large riparian forests . The riparian forests were most pronounced along the Sacramento River and the lower Mokelumne River below its confluence with the Cosumnes River . More extensive woodlands were prominent on
9401-541: The farmable land in the Delta had been reclaimed by the 1920s. The Delta produces crops valued at about $ 650 million annually (for the 1998–2004 period), making it one of the most productive farming regions of the United States in terms of crop value per unit area. Agriculture provides secondary benefits of over $ 2 billion to the local economy. Major crops grown in the Delta include corn, grain, hay, sugar beets, alfalfa, tomatoes, asparagus, and safflower; various fruits are also raised here, as well as some livestock. Crops in
9520-402: The flood of 1878 wiped out the last of the elk herds in the Delta. The Delta is home to approximately 22 species of fish, including several Pacific salmon species, striped bass , steelhead trout , American shad and sturgeon . About two-thirds of California's salmon pass through the Delta on their way upstream to spawn. The small Delta smelt is a key indicator species for the health of
9639-502: The fringes of the Delta bordering the riparian zones. Composed primarily of valley oak , box elder and Oregon ash , these oak woodlands grew in bands that stretched up to 3 miles (4.8 km) inland. Farther away from water sources, vegetation gave way to grassland . The water hyacinth has become one of the most destructive plants to the Delta water way. Within one year it will spread and cover as much as 6,500 square feet (600 m ) of water space in one growing season. It has become
9758-540: The greater San Francisco Bay Area , which is one of the most geologically complex regions in the world. The great local mountain Mount Diablo has been formed and continues to be elevated by compressive forces resulting from the action of plate tectonics and at its upper reaches presents ancient seabed rocks scraped from distant oceanic sedimentation locations and accumulated and lifted by these great forces. Younger deposits at middle altitudes include pillow lavas ,
9877-614: The head of Suisun Bay, although they are linked upstream by the Georgiana Slough , which was first used by steamboats in the 19th century as a shortcut between Sacramento and Stockton . The southwestern part of the Delta is also transected by the Middle River and Old River, former channels of the San Joaquin. These rivers transport more than 30 million acre-feet (8.9 cu mi; 37 km ) of water through
9996-592: The highly urban environments of the near East Bay. Owing to its extensive waterfront on San Francisco , San Pablo , and Suisun bays the northwestern and northern segments have long been sites for heavy industry, including a number of still active oil refineries (particularly Chevron in Richmond, Phillips 66 in Rodeo , Shell Oil (now PBF) and Tesoro (now Marathon)- in Martinez), chemical plants ( Dow Chemical ) and
10115-557: The initial impetus for building dams on Central Valley rivers to boost dry-season freshwater flows. This eventually became the federal Central Valley Project (CVP), California's first major statewide water system, most of which was built between the 1930s and the 1960s. Today, the California Aqueduct and the Delta-Mendota Canal , two of the state's largest water conveyance facilities, both draw water from
10234-572: The last Ice Age. During the Ice Age global sea levels were about 300 ft (91 m) lower than today, and the Delta region, as well as Suisun Bay, the Carquinez Strait and San Francisco Bay, were a river valley through which the continuation of the Sacramento and San Joaquin Rivers flowed to the Pacific Ocean. When sea levels rose again, ocean water backed up through the Carquinez Strait into
10353-404: The lower trophic levels. There have also been large amounts of nutrients monitored in the Delta as a result of various human activities. The increased presence of Microcystis aeruginosa blooms in the Delta represents a continual threat for species at multiple trophic levels. The lower trophic levels are affected from both reduced diversity as well as reduced numbers through competition. When
10472-488: The mid-19th century, most of the region has been gradually claimed for agriculture. Wind erosion and oxidation have led to widespread subsidence on the Central Delta islands; much of the Delta region today sits below sea level, behind levees earning it the nickname "California's Holland ". Much of the water supply for Central California and Southern California is also derived from the Delta, via pumps located at
10591-399: The more prosperous farms have been preserved as museums and cultural centers and one of the more rustic examples has been preserved as a working demonstration ranch, Borges Ranch . In the 1860 United States Census, Contra Costa County had a population of 4,381. During World War II, Richmond hosted one of the two Bay Area sites of Kaiser Shipyards and wartime pilots were trained at what
10710-628: The name of the mountain, one in 2005 and another in 2011, but these were not successful. The 2010 United States Census reported that Contra Costa County had a population of 1,049,025. The racial makeup of Contra Costa County was 614,512 (58.6%) White ; 97,161 (9.3%) African American ; 6,122 (0.6%) Native American ; 151,469 (14.4%) Asian (4.6% Filipino, 3.8% Chinese, 2.1% Indian); 4,845 (0.5%) Pacific Islander ; 112,691 (10.7%) from other races ; and 62,225 (5.9%) from two or more races. There were 255,560 people (24.4%) of Hispanic or Latino ancestry, of any race; 17.1% of Contra Costa County's population
10829-484: The negative attributes associated with climate change like reduced precipitation and increased temperatures could further increase the possibility of cyanobacteria blooms in the Delta. The high prevalence of nutrient concentrations in the Delta also plays a significant part in the increased frequency of Microcystis aeruginosa blooms. Microcystis benefits greatly from anthropogenic inputs of nitrogen which allows it to out-compete other primary producers and dominate
10948-546: The northwestern side of the Delta. The Stockton Ship Channel is a dredged and partially straightened section of the San Joaquin River cutting directly through the Delta from the Port of Stockton to the San Joaquin's confluence with the Sacramento near Antioch. "The virgin California Delta was so vast, wild and confusing – its sloughs meandered everywhere and led nowhere – that John C. Frémont lost
11067-525: The open spaces that stretch to the north. The open spaces controlled by cities, the East Bay Regional Park District, Mount Diablo State Park, and various regional preserves now adjoin and protect most of the elevated regions of the mountain. The name Mount Diablo is said to originate from an incident involving Spanish soldiers who christened a thicket as Monte del Diablo when natives they were pursuing apparently disappeared into
11186-987: The park. MDSP was the first of twenty-nine Diablo-area parks and preserves that have been created around the peaks; today these preserves protect more than 89,000 acres (360 km ). These Diablo public lands stretch southeast and include the Concord Naval Weapons Station , Shell Ridge Open Space and Lime Ridge Open Spaces near Walnut Creek, to the State Park, and east to the Los Vaqueros Reservoir watershed and four surrounding East Bay Regional Park District preserves, including Morgan Territory Regional Preserve , Brushy Peak Regional Preserve , Vasco Caves Regional Preserve , and Round Valley Regional Preserve . The new Marsh Creek State Park , formerly known as Cowell Ranch State Park, and Black Diamond Mines Regional Preserve , are among
11305-431: The passage of large cargo ships. The Sacramento River corridor has been maintained to a depth of 7 ft (2.1 m) as early as 1899, and was deepened to 30 ft (9.1 m) in 1955. The Stockton Ship Channel has been dredged since 1913; however, its present depth of 37 ft (11 m) was only achieved in 1987. The Delta is also home to the port of Benicia , an automobile and bulk shipping facility. Petroleum
11424-614: The peat soil of the former tidal marsh was exposed to oxygen. As the oxygen-rich peat soil decomposed and then released carbon dioxide, profound subsidence of the land resulted, of up to 25 feet since the late 1800s. Currently, most of the Delta is below sea level, with a great deal of the western and central Delta at least 15 feet (4.6 m) below sea level. The California Department of Water Resources has experimented with re-flooding areas for wetland restoration , in order to sequester carbon and rebuild soil levels . In addition, shallow flooding of land to restore anaerobic conditions
11543-599: The population, while ethnic Asians constituted 13.1%. Latinos, representing people of Spanish, Portuguese, indigenous and mestizo populations of the Western hemisphere, comprised 21.1% of the county population. In 2000, there were 344,129 households, out of which 35.4% had children under the age of 18 living with them, 54.5% were married couples living together, 11.5% had a female householder with no husband present, and 29.6% were non-families. 22.9% of all households were made up of individuals, and 8.00% had someone living alone who
11662-403: The present-day Carquinez Strait and San Francisco Bay . The drainage of all the water through this narrow gap formed a bottleneck in the Central Valley's outflow; this constriction is essential to provoke the slowing of river current and the resulting sediment deposits that now make up the Delta. The Delta in its contemporary (pre-1850s) state began to form about 10,000 years ago at the end of
11781-617: The product of undersea volcanic eruptions. The Bay Miwok , Yokut and Ohlone people lived in the area now known as Contra Costa County before the arrival of Spanish colonists. The Volvon triblet of the Miwok lived on Tuyshtak ( Mount Diablo near present day Walnut Creek ) until they were forcibly moved from their land into the Spanish missions in the early 1800s. The Saklan tribe lived between Moraga , along San Leandro Creek , to Lafayette . Beginning in 1772, expeditions of Spanish missionaries and soldiers from Mission San José entered
11900-513: The same amount of land that has been developed to date. Agricultural interests in the Delta were protected by the building of levees, a colossal effort first undertaken by Chinese laborers from the 1850s to the 1870s. The Board of Reclamation, formed in 1861, collectivized levee construction in the Delta by grouping islands into areas known as reclamation districts . The early levees were built of peat, and were highly susceptible to wind and water erosion. The Great Flood of 1862 obliterated much of
12019-464: The seasons and tides. The height of these natural levees, formed from overbank deposits of sediments deposited by annual river floods, ranged from one foot (0.30 m) above mean high tide at Sherman Island on the Sacramento River, to seven to eight feet (2.1 to 2.4 m) at Andrus , Staten and Tyler Islands, located further east near the Mokelumne River. An estimated 60 percent of
12138-689: The southern end of the Delta at the Clifton Court Forebay . Built in the mid-twentieth century, the former supplies water to the Los Angeles Basin and coastal central California via the State Water Project ; the latter, a part of the CVP, provides supplies of irrigation water in the fertile San Joaquin Valley. Although the vast majority of water supplied by these projects is used for agriculture and urban areas, some water
12257-506: The southern end of the Delta. The pumps deliver water for irrigation in the San Joaquin Valley and municipal water supply for Southern California. The Delta consists of approximately 57 reclaimed islands and tracts but there are nearly 200 islands in the delta that are named or not named. These are all surrounded by 1,100 miles (1,800 km) of levees that border 700 miles (1,100 km) of waterways. The southwestern side of
12376-411: The surrounding valleys began to threaten the open space of the mountain. In 1971, MDSP consisted of 6,788 acres (27.5 km ). That year, concerned residents formed the non-profit organization Save Mount Diablo to raise funds and awareness to protect more open space. In addition to encouraging acquisition by the state and local authorities, SMD started fundraising and acquiring properties to transfer to
12495-656: The terminus of the California trail. This led to the Bear Flag Revolt in 1846 when about 30 settlers originally from the United States declared a republic in June 1846 and were enlisted and fighting under the U.S. flag by July 1846. Following the Mexican–American War of 1846–48, California was controlled by U.S. settlers organized under the California Battalion and the U.S. Navy 's Pacific Squadron . After some minor skirmishes, California
12614-518: The thicket. Anglo settlers later misunderstood the use of the word 'monte' (which can mean 'mountain', or 'thicket'), and applied the name to the most obvious local landmark. According to the Contra Costa Times , in 2011, there were rumors that Contra Costa County was going to rename the mountain as "Mt. Ronald Reagan" or "Mt. Reagan", after the former US president and California governor. Residents have generated multiple petitions to change
12733-481: The thin-shelled English Walnut branches grafted to the hardy and disease-resistant American Walnut root stock. In the Moraga region, pears dominated, and many old (but untended) roadside trees are still picked seasonally by passers-by. In eastern county, stone fruit, especially cherries, is still grown commercially, with seasonal opportunities for people to pick their own fruit for a modest fee. The Contra Costa Canal ,
12852-490: The vicinity of the Delta, including one to John Augustus Sutter , who started the first significant European settlement in the Central Valley just north of the Delta near present-day Sacramento. The Spanish conscripted large numbers of Native Americans for labor on missions; many Native Americans fled deep into the Delta in order to escape their European masters. However, this did not protect them from diseases. A malaria epidemic in 1833 decimated local native populations; this
12971-581: The world located this far inland is the Pearl River Delta in China. The main source rivers include the Sacramento River from the north, the San Joaquin from the southeast, and the Calaveras and Mokelumne Rivers from the east. The Calaveras and Mokelumne are both tributaries of the San Joaquin River. The Sacramento and San Joaquin Rivers join at the western end of the Delta near Pittsburg , at
13090-545: Was $ 73,039 (these figures had risen to $ 75,483 and $ 87,435 respectively as of a 2007 estimate). Males had a median income of $ 52,670 versus $ 38,630 for females. The per capita income for the county was $ 30,615. About 5.4% of families and 7.6% of the population were below the poverty line , including 9.8% of those under age 18 and 6.0% of those age 65 or over. In 2000, the largest denominational groups were Catholics (with 204,070 adherents) and Evangelical Protestants (with 74,449 adherents). The largest religious bodies were
13209-403: Was 65 years of age or older. The average household size was 2.72 and the average family size was 3.23. In the county, the population was spread out, with: The median age was 36 years. For every 100 females there were 95.4 males. For every 100 females age 18 and over, there were 92.2 males. The median income for a household in the county was $ 63,675, and the median income for a family
13328-412: Was cheaper and simpler than other fertile regions of California. As a result, the Delta remained California's richest farming region (alongside Los Angeles County ) until the 1940s, when massive federal water projects finally made possible the full-scale irrigation of the main body of the Central Valley. Today, the Delta is still among the state's most productive farming regions. In 1850, Congress passed
13447-576: Was due to the postwar baby boom of the era creating demand for three- and four-bedroom houses with large yards that were unaffordable or unavailable in the established bayside cities. A number of large companies followed their employees to the suburbs, filling large business parks. The establishment of a large, prosperous population in turn fostered the development of large shopping centers and created demand for an extensive supporting infrastructure including roads, schools, libraries, police, firefighting, water, sewage, and flood control. The establishment of
13566-693: Was of Mexican ancestry, while 1.9% was of Salvadoran heritage. As of the census of 2000, there were 948,816 people, 344,129 households, and 242,266 families residing in the county. The population density was 1,318 inhabitants per square mile (509/km ). There were 354,577 housing units at an average density of 492 units per square mile (190 units/km ). Of residents who identified with European ethnicities, 9.0% were German, 7.7% Irish, 7.3% English, and 6.5% Italian ancestry according to Census 2000 . 74.1% spoke English, 13.1% Spanish, and 2.6% Tagalog . By 2005, 53.2% of Contra Costa County's population were non-Hispanic whites. African Americans made up 9.6% of
13685-433: Was one of the original 27 counties of California, created in 1850 at the time of statehood. The county was originally to be called Mt. Diablo County, but the name was changed prior to incorporation as a county. The county's Spanish language name means opposite coast , because of its location opposite San Francisco, in an easterly direction, on San Francisco Bay . Southern portions of the county's territory, including all of
13804-506: Was one square league, or about seven square miles, or 4,400 acres (17.8 square kilometers), maximum to one individual was eleven leagues, or 48,400 acres (195.9 km ), including no more than 4,428 acres (17.9 km ) of irrigable land. Rough surveying was based on a map, or diseño , measured by streams, shorelines, and/or horseman who marked it with rope and stakes. Lands outside rancho grants were designated el sobrante , as in surplus or excess, and considered common lands. The law required
13923-476: Was probably exacerbated by the marshy geography of the area, which bred large amounts of mosquitoes. The agricultural value of the Delta was first recognized during the California Gold Rush , when farmers planted orchards on Delta islands to provide fresh fruit for mining camps in the Sierra Nevada . Because of the flat terrain coupled with year-round availability of fresh water, irrigation here
14042-762: Was the last Republican presidential candidate to win the county. In the United States House of Representatives , Contra Costa County is split among three congressional districts: In the State Assembly , Contra Costa County is split among four districts: In the State Senate , the county is split among three districts: Democrats hold wide advantages in voter registration numbers in all political subdivisions in Contra Costa County. The Democrats' largest registration advantage in Contra Costa
14161-534: Was under U.S. control by January 1847 and formally annexed and paid for by the U.S. in 1848. By 1850, California's population of over 100,000 was rapidly growing due to the gold rush and the large amount of gold being exported east, which gave California enough clout to choose its own boundaries, write its own constitution, and be admitted to the Union as a free state in 1850 without going through territorial status as required for most other states. In 1850 California had
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