Search USGS⌕ Search

SEARCH · Search USGS

Results for “Newsletter”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
USGS2001

Behind the energetics of the asiatic clam, Potamocorbula amurensis, in San Francisco Bay

The Asian clam (Potamocorbula amurensis) has played a key role in the food web of northern San Francisco Bay since its invasion in the fall of 1986. It has been associated with a dramatic decline in primary production, loss of a zooplankton species and a native mysid shrimp, the probable decline in striped bass, and has introduced alternative pathways for contaminant cycling in the bay food web.

Interagency Ecological Program Newsletter↗
USGS2000

Exposure of delta smelt to dissolved pesticides in 1998 and 1999

Delta smelt is a threatened species in the San Francisco Bay Estuary. Pesticide toxicity is a possible cause for the need to list this fish (Bennett and Moyle 1996; Moyle and others 1996). Numerous pesticides are transported into the estuary from area rivers (MacCoy and others 1995). However, there are minimal data to document the presence, or absence, of pesticides within delta smelt habitat, especially during their vulnerable early life stages. This study, conducted by the U.S. Geological Survey (USGS), documents the occurrence of pesticides within delta smelt habitat; specifically, the length and variability of their potential exposure to multiple dissolved pesticides. This article reviews delta smelt habitat and early life stages followed by an explanation of the study design for assessing pesticide exposure. Results show the co-occurrence of multiple pesticides and delta smelt in their native habitat; these results are presented within the context of possible toxic effects to delta smelt. Finally, the annual variability of pesticide distributions is discussed.

Interagency Ecological Program Newsletter↗
USGS1995

USGS supports ecosystem management in the San Francisco bay and delta

In the past several years, the Department of the Interior has ,l?laced particular emphasis on "ecosystem management" - the integration of scientific knowledge of ecological relationships with resource management practices to sustain ecological, cultural, and economic systems in broad habitat areas; eg., forest, desert, and aquatic habitats. The goal of ecosystem management is to understand the habitat requirements of many species and thereby assess the impact of a variety of human activities on regional biodiversity rather than to manage for individual species. In support of the management of the natural resources of San Francisco Bay and the delta, the USGS is augmenting its ongoing research program to provide additional research, monitoring, and assessment information and to improve the availability of that information. Following a workshop with resource and regulatory agency representatives, hosted by the USGS in early 1994, USGS researchers identified specific areas where existing and new scientific information could contribute to resolving some of the critical bay and delta land and aquatic management issues. The "ecosystems initiative" effort now underway addresses questions in three areas: Freshwater flow, including sediment and contaminant transport. Wetlands. Information and data access. Following is a brief description of activities being supported by this initiative.

Interagency Ecological Program Newsletter↗
USGS1993

Continuous flow measurements using fixed ultrasonic meters

USGS has or soon will be installing four continuous flow-monitoring stations in the delta that will use ultrasonic velocity meters (DVM). Funding for the stations has been provided by USGS, DWR, USBR, and Contra Costa Water District.

Interagency Ecological Program Newsletter↗
USGS1996

Sediment inflow to the delta from the Sacramento and San Joaquin Rivers

USGS routinely measures the daily suspended sediment load entering the delta with the flows of the Sacramento and San Joaquin rivers. Most of the suspended sediment that flows into the delta is carried by these two rivers, but it also enters from Yolo Bypass; the Mokelumne, Calaveras, and Cosumnes rivers; and several smaller streams. This article presents suspended sediment data for the Sacramento and San Joaquin rivers, and compares the data collected during the water year 1995 to statistically analyzed data from the long-term record.

Interagency Ecological Program Newsletter↗
USGS1998

Indirect measurement of Delta outflow using ultrasonic velocity meters and comparison with mass-balance calculated outflow

A measurement of the quantity of water flowing from the Sacramento-San Joaquin Delta into Suisun Bay (Delta outflow) has been desired by those studying and managing the San Francisco Bay/Delta estuary since the 1920s. Historically, Delta outflow has been estimated using a mass-balance calculation that uses measured Delta inflows and exports, and imprecise estimates of consumptive use for the approximately 2,000 small agricultural diversions with the Delta. The DWR has estimated Delta outflow for 1929 to present using the computer program DAYFLOW.

Interagency Ecological Program Newsletter↗
USGS1999

Measured flow and tracer-dye data for spring 1996 and 1997 for the south Sacramento-San Joaquin Delta, California

During the spring of years when the flow of the San Joaquin River is less than 7,000 cubic feet per second (ft 3 /s) a temporary rock barrier is installed by the California Department of Water Resources (DWR) at the head of Old River (HOR) in the south Sacramento-San Joaquin Delta to prevent out migrating salmon in the San Joaquin River from entering Old River and being drawn to the State and federal pumping facilities (Figure 1). The export rate of the pumping facilities also is reduced during these migration periods to minimize the draw of fish to the export facilities through the other channels connected to the San Joaquin River north of the HOR such as Turner Cut, Columbia Cut, and Middle River.

Interagency Ecological Program Newsletter↗
USGS1995

Pathway models could aid management of contaminants

Heavy metal and trace organic contaminants are often cited as factors that could affect the riclmess of the biological community of San Francisco Bay as well as the health of resident organisms. Silver (Ag), selenium (Se), mercury (Hg), copper (Cu), nickel (Ni), chromium (Cr), and cadmium (Cd) are among the trace elements of current regulatory interest. All these elements can be toxic to estuarine organisms in minute quantities. However, understanding their toxicity in nature has proven a difficult challenge. In general, it is difficult to prove how pollutants are affecting ecosystems. The undisturbed "baseline" condition in San Francisco Bay is not always well enough understood to identify whether certain processes are affected or unaffected by contamination. Sources of disturbance (flow diversions, drought, invasion of exotic species, etc.) occur in addition to chemical contamination. Responses to contamination in individual organisms, populations, and commumties are seldom pollutant-specific, and the complex responses to moderate levels of contamination are not well known.

California↗
USGS2012

Long-term change along the Colorado River in Grand Canyon National Park (1889-2011)

The Colorado River and its riverine resources have undergone profound changes since completion of Glen Canyon Dam in 1963, as every river runner with any history in Grand Canyon will attest. Long-term monitoring data are difficult to obtain for high-value resource areas (Webb et al. 2009), particularly in remote parts of national parks, yet these data are important to determining appropriate actions for restoration of resources and (or) potential modifications of flow releases on regulated rivers. The river corridor through the bottom of Grand Canyon creates a challenging environment for change-detection monitoring techniques (Belnap et al. 2008).

Arizona↗
USGS2001

Mercury-contaminated sediments in the North Bay: A legacy of the Gold Rush

A legacy of the Gold Rush is mercury-contaminated sediments in the Bay. Miners used mercury to extract gold from tailings during the gold rush. A large amount of this mercury (some estimates are as great as 10,000 tons) was lost during extraction to the watershed during the gold rush era. This mercury-contaminated hydraulic mining debris made its way to the Bay.

Northern California Geological Survey Newsletter↗
USGS1987

Standardization of stain used for diagnosing erythrocytic inclusion body syndrome (EIBS)

Erythrocytic inclusion body syndrome (EIBS), a viral erythrocytic necrosis (VEN)-like disease, has been observed in several areas in the Northwest. This virus disease is clinically diagnosed by microscopic examination of blood smears for intracytoplasmic erythrocytic inclusion bodies. Fish biologists involved in EIBS diagnostic work have been using several types of hematological stains. It became apparent that standardization of the staining procedure was needed. Comparative tests were conducted on blood smears and kidney imprints with the following commonly used blood stains: (1) Leishman-Giesma, (2) Pinacyanol chloride, (3) Powell 's Giemsa, (4) Harleco's Giemsa, (5) Diff Quik differential stain, (6) Wright's. Pinacyanol chloride stain was found to be the most consistent. The following staining procedure is recommended.

Fish Health Newsletter↗