Santa Margarita River Research Articles

A Basin‐Scale Approach to Estimating Recharge in the Desert: Anza‐Cahuilla Groundwater Basin, CA

AbstractThe Anza‐Cahuilla groundwater basin located mainly in the semi‐arid headwaters of the Santa Margarita River watershed in southern California is the principle source of groundwater for a rural disadvantaged community and two Native American Tribes, the Ramona Band of Cahuilla and the Cahuilla. Groundwater in the study area is derived entirely from precipitation and managing groundwater sustainably requires an accurate assessment of the water balance components, yet long‐term estimates do not exist. Demand for groundwater in the region has increased and groundwater quality has decreased due to population growth and increased irrigated cropland. To characterize monthly long‐term natural recharge and runoff estimates, a physically‐based water balance model (Basin Characterization Model) was locally calibrated and validated using nearby streamgages and published estimates of climatic and hydrologic variables. The average modeled annual recharge and runoff from 1981 to 2010 was 5.4 × 106 and 1.2 × 107 m3, respectively, for the study area. Recharge and runoff do not reliably occur in large amounts every year and recharge rarely occurs in the groundwater basin footprint. These long‐term estimates can be used by water managers, stakeholders, and Native American Tribes to develop plans for sustainable management of future water resources, and as inputs to a three‐dimensional groundwater model.

Evaluation of the subseasonal forecast skill of floods associated with atmospheric rivers in coastal Western U.S. watersheds

AbstractAtmospheric rivers (ARs) are responsible for up to 90% of major flood events along the U.S. West Coast. The timescale of subseasonal forecasting (two weeks to one month) is a critical lead time for proactive mitigation of flood disasters. The NOAA/Climate Testbed Subseasonal Experiment (SubX) is a research-to-operations project with almost immediate availability of forecasts. It has produced a reforecast database that facilitates evaluation of flood forecasts at these subseasonal lead times. Here, we examine the SubX driven forecast skill of AR-related flooding out to 4-week lead using the Distributed Hydrology Soil Vegetation Model (DHSVM), with particular attention to the role of antecedent soil moisture (ASM), which modulates the relationship between meteorological and hydrological forecast skill. We study three watersheds along a transect of the U.S. West Coast: the Chehalis River basin in Washington, the Russian River basin in Northern California, and the Santa Margarita River basin in Southern California. We find that the SubX driven flood forecast skill drops quickly after week 1, during which there is relatively high deterministic forecast skill. We find some probabilistic forecast skill relative to climatology as well as ensemble streamflow prediction (ESP) in week 2, but minimal skill in weeks 3-4, especially for annual maximum floods, notwithstanding some probabilistic skill for smaller floods in week 3. Using ESP and reverse-ESP experiments to consider the relative influence of ASM and SubX reforecast skill, we find that ASM dominates probabilistic forecast skill only for small flood events at week 1, while SubX reforecast skill dominates for large flood events at all lead times.

Floods due to Atmospheric Rivers along the U.S. West Coast: The Role of Antecedent Soil Moisture in a Warming Climate

AbstractPrecipitation extremes are projected to become more frequent along the U.S. West Coast due to increased atmospheric river (AR) activity, but the frequency of less intense precipitation events may decrease. Antecedent soil moisture (ASM) conditions can have a large impact on flood responses, especially if prestorm precipitation decreases. Taken together with increased antecedent evaporative demand due to warming, this would result in reduced soil moisture at the onset of extreme precipitation events. We examine the impact of ASM on AR-related floods in a warming climate in three basins that form a transect along the U.S. Pacific Coast: the Chehalis River basin in Washington, the Russian River basin in Northern California, and the Santa Margarita River basin in Southern California. We ran the Distributed Hydrology Soil Vegetation Model (DHSVM) over the three river basins using forcings downscaled from 10 global climate models (GCMs). We examined the dynamic role of ASM by comparing the changes in the largest 50, 100, and 150 extreme events in two periods, 1951–2000 and 2050–99. In the Chehalis basin, the projected fraction of AR-related extreme discharge events slightly decreases. In the Russian basin, this fraction increases, however, and more substantially so in the Santa Margarita basin. This is due to increases in AR-related extreme precipitation events, as well as the fact that the relationship of extreme precipitation to extreme discharge is strengthened by projected increases in year-to-year volatility of annual precipitation in California, which increases the likelihood of concurrent occurrence of large storms and wet ASM conditions.

Conservation Genetics of an Urban Desert Fish, the Arroyo Chub

AbstractUrbanization, habitat degradation, fragmentation, and invasive species have led to the severe decline or extirpation of many endemic southern California freshwater fish species, including the Arroyo Chub Gila orcuttii, which has declined precipitously in recent years. Classified by the California Department of Fish and Wildlife as a species of high concern, the Arroyo Chub is native to the Los Angeles, San Gabriel, San Luis Rey, Santa Ana, and Santa Margarita rivers and Malibu and San Juan creeks. To examine Arroyo Chub population structure and genetic diversity within the species' native range, we used 10 microsatellite markers to genotype 259 individuals. We observed moderate to high genetic diversity and population differentiation both between and within drainages; Bayesian clustering supported eight distinct clusters of Arroyo Chub corresponding to eight isolated populations. Of these populations, the Big Tujunga Creek population (Los Angeles River) was the least genetically differentiated (genetic differentiation index FST = 0.048–0.208) and also had the highest genetic diversity (observed heterozygosity Ho = 0.890). Populations in Malibu Creek, Pacoima Canyon (Los Angeles River), and the Santa Margarita River were the most genetically differentiated (FST = 0.163–0.400), had the lowest genetic diversity (Ho = 0.556–0.680), and showed evidence of past bottlenecks. Arroyo Chub at these localities are at risk for continued loss of genetic diversity due to drift and small population sizes; therefore, we suggest that in the event of extirpation, translocations from the most closely related source populations should be considered. However, we recommend that management efforts focus on improving habitat quality and habitat area for Arroyo Chub in order to maximize population genetic diversity and adaptive potential over time.Received July 10, 2015; accepted November 16, 2015

Surface-dwelling and Subterranean Invertebrate Fauna Associated with Giant Reed (Arundo donax Poaceae) in Southern California

In the southwestern United States giant reed, Arundo donax, is a non-native invasive plant that has become widely established in moist places and forms its largest stands along riparian corridors. The most widely reported negative effects include competition with native species, increased rate of transpiration, increased potential for wildfires, and stream channel and bank alteration. However, little is known about the faunal communities associated with this plant and the potential effects on native fauna. In this study, we focused our efforts on determining the faunal composition specifically from rhizome clumps of A. donax from a site located along the Santa Margarita River in San Diego County, California. A total of 2590 individual macro-invertebrates were collected and identified, and represented 64 species from 7 classes. No sensitive species and few vertebrates were found to be in association with A. donax rhizome clumps. Four non-native invertebrate species made up 43% of the total number of captured invertebrates, and 31% of the sampled invertebrates were confirmed as native species. This study demonstrates that A. donax rhizome clumps, and the soils associated with them, provide habitat for several native macro-invertebrate species, but can be dominated by a greater abundance of non-native species.

Water Supply Challenges and Tmdl Development in the Santa Margarita River Watershed

Water Supply Challenges and Tmdl Development in the Santa Margarita River Watershed

UNINTENDED CONSEQUENCES OF NUTRIENT CRITERIA ON WATER RESOURCE PLANNING IN THE SANTA MARGARITA RIVER WATERSHED

UNINTENDED CONSEQUENCES OF NUTRIENT CRITERIA ON WATER RESOURCE PLANNING IN THE SANTA MARGARITA RIVER WATERSHEDThe Santa Margarita River Watershed encompasses an area of approximately 740 square miles and falls within Riverside and San Diego Counties. As a result of the nutrient standards that have been applied within the watershed, no reclaimed water discharges to any part of the watershed. The potential dischargers have determined that at this time it is more cost effective to pipe reclaimed water to...Author(s)Nicole RowanMichael SavageWilliam SteeleSourceProceedings of the Water Environment FederationSubjectSession 7: Biological Quality Criteria and Human HealthDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2004ISSN1938-6478SICI1938-6478(20040101)2004:16L.935;1-DOI10.2175/193864704784147485Volume / Issue2004 / 16Content sourceWEFTECFirst / last page(s)935 - 963Copyright2004Word count173

Cumulative impacts of Section 404 Clean Water Act permitting on the riparian habitat of the Santa Margarita, California Watershed

The Santa Margarita River is one of the few remaining free-flowing river systems on the Southern California coastal plain, and it provides one of the most expansive, unspoiled riparian habitats in Southern California. There is concern among resource managers that the cumulative impacts associated with rapid development of the upper watershed will degrade the ecological integrity of the entire watershed. In response to this concern, we assessed the impacts of development projects in this watershed, which were subject to regulation under Section 404 of the Clean Water Act. Cumulative impacts were assessed by comparing the conditions present at each project site prior to issuance of the Section 404 permit to conditions present after issuance of the permit. Changes between pre- and post-project site conditions were evaluated using a semantic categorization for the following six criteria: endangered species habitat, structural diversity, spatial diversity, undeveloped open space, linear contiguity, and adjacent habitat. The impact assessment showed that although the Section 404 permit program has attenuated project impacts, it has failed at minimizing cumulative impacts. Projects permitted under Section 404 contributed to the disruption of movement corridors linking the habitats of the upper and lower watershed and resulted in extensive floodplain encroachment, which may have hydrologic as well as ecological implications. More importantly, this assessment identified the types of activities and habitat functions that should be addressed during revisions in permitting procedures and should be emphasized in the watershed planning process. These conclusions will be incorporated into an ongoing Advanced Identification study sponsored by the U.S. Environmental Protection Agency and U.S. Army Corps of Engineers to develop a management plan for the Santa Margarita Watershed.

Dissolved-Oxygen Analysis with Temperature Dependence

Water-quality models to predict oxygen dynamics in streams require estimates of rates of reaeration, respiration, and primary production, which are often evaluated through diel studies. Simple, approximate methods of parameter estimation are desirable at the scoping level, and are often used for waste-load allocation studies. Scoping methods often assume that reaeration and respiration are constant over the diel period. Use of such methods, however, can yield unrealistic parameter estimates for shallow streams with a significant range of diel water temperatures, because both reaeration and respiration rates as well as the saturation concentration of dissolved oxygen are temperature-dependent. Based on our work on the Santa Margarita River in Southern California, this paper presents a modified approach to dissolved-oxygen–rate parameter estimation that takes temperature variation into account. Using a simple finite-difference approximation, temperature-normalized parameter estimates are readily optimized in a spreadsheet application. The approach is applicable to many shallow streams in which diel temperature variability is significant.

A LUMPED STREAM-AQUIFER MODEL TO ASSESS RECLAIMED WATER IMPACTS

: A lumped, in time and space, model of stream-aquifer interactions is developed. The model is based upon mass balance and ancillary phenomenological equations that can evaluate changes in streamflow and groundwater quantity and quality. The model is applied to the Santa Margarita River, San Diego County, California to assess the impacts of proposed discharges of reclaimed wastewater on streamflows and underlying groundwaters. The model is relatively simple and economical to apply, thus minimizing analysis costs.

The Controversy over Water Rights in the Santa Margarita River

Research Article| February 01 1956 The Controversy over Water Rights in the Santa Margarita River W. Henry Cooke W. Henry Cooke Search for other works by this author on: This Site PubMed Google Scholar Pacific Historical Review (1956) 25 (1): 1–28. https://doi.org/10.2307/3634391 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation W. Henry Cooke; The Controversy over Water Rights in the Santa Margarita River. Pacific Historical Review 1 February 1956; 25 (1): 1–28. doi: https://doi.org/10.2307/3634391 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentPacific Historical Review Search This content is only available via PDF. Article PDF first page preview Close Modal You do not currently have access to this content.

Wave, longshore current, and beach profile records for Santa Margarita River Beach, Oceanside, California, 1949

The results of ten months of measurements of waves, longshore currents, and beach conditions for Santa Margarita River Beach are presented. Tables and graphs give the height, period, and steepness of the incident waves as measured by a subsurface, differential‐type pressure recorder; breaker heights as computed from these data; observed wave directions; longshore current measurements, both magnitude and direction, as obtained by tracing dye thrown into the water; and beach profiles measured along three ranges 500 ft apart from the berm to a depth of about 25 ft. It was found that the three sets of profiles were not consistent in regard to their relationship with varying wave conditions, and further that the type of beach profile (storm or ordinary) apparently did not bear the same relationship to the wave steepness as has been found in laboratory studies.

Federal Claims to California Water

♦The 1952 Legislature adopted Senate Concurrent Resolution No. 1, referring to the Santa Margarita River litigation, as oppressive and regrettable action brought by the United States to adjudicate the water rights of the Santa Margarita River threatens to forever stop the growth and development of the many attractive and productive settlements, towns and agricultural communities in the Santa Margarita River Basin. Assembly Joint Resolution No. 8, beginning: Whereas, a decisive moment has arrived in the struggle of citizens of California against unwarranted federal encroachment upon individual and state rights in the 'Fallbrook Water Seizure Case,' concludes : That the Legislature deplores the pending federal suit to seize water rights in California under a specious guise of 'national The case is entitled United States