The lower Merced River and Mustang Creek watersheds and four other watershe...
At a typical study site, several methods are used to collect water and chem...
Data Collection in the lower Merced River and Mustang Creek Watersheds, 200...
The U.S. Geological Survey (USGS) is studying five watersheds across the Nation to better understand how natural factors and agricultural management practices (AMPs) affect the transport of water and chemicals. Natural factors include climate and landscape (soil type, topography, geology), and AMPs include practices related to tillage, irrigation, and chemical application. The study approach is similar in each watershed so that we can compare and contrast the results and more accurately predict conditions in other agricultural settings.
The lower Merced River and Mustang Creek watersheds, along with the other four watersheds, represent nationally important agricultural settings (chemical use, crops, and AMPs) and natural settings (climate, geology, topography, and soils). Mustang Creek is a small tributary to the Merced River, which drains into the San Joaquin River. AMPs are diverse throughout the lower Merced River watershed, which contains orchards, vineyards, row crops, dairies, and other animal operations typical of the San Joaquin Valley.
Other features of the watershed that are relevant to this study:
Data Collection in the lower Merced River and Mustang Creek Watersheds, 2003–2004
| What kind of data | Why the data are collected | How often |
|---|---|---|
| Meteorological data, including rainfall, wind speed, solar radiation, and air temperature. Soil temperature and moisture | To determine amount of precipitation and estimate amount that reaches the water table and how much is lost to evapotranspiration | Continuously for 2 years |
| Streamflow at 2 newly installed gaging stations within the Mustang Creek watershed. Streamflow on the Merced River measured by California Dept. of Water Resources. | To interpret water-quality data correctly (the amount of water in streams affects chemical concentrations) | Continuously |
| Quality of stream water, runoff water, rain water1 | To quantify the transport and behavior of natural and agricultural chemicals | Several times a year (>14 samples) for 2 years, with intensive sampling during application season |
| Ground-water levels in wells | To determine direction of ground-water flow, which affects transport of chemicals | At least quarterly in some wells, continuously in others for at least 1 year |
| Quality of ground water, soil water, and shallow water in and around streambed/riparian zone1 | To quantify the transport and behavior of natural and agricultural chemicals | At least quarterly for 1 year |
| Quality of sediment in streambed and soils in agricultural fields1 | To quantify the storage, behavior, and transport of water and chemicals in the soils and sediment | At least once during study |
1In this study, water-quality and sediment-quality data include concentrations of nutrients (nitrogen and phosphorous), pesticides and pesticide breakdown products, and natural constituents and properties, including major ions (calcium, magnesium, chloride, etc.), organic carbon, dissolved oxygen, and temperature.
We are working with local growers and land owners to gain access to study sites. We also need information about the watershed and about current as well as historical agricultural management practices—past practices also affect concentrations of agricultural chemicals in ground and surface water.
We will report the findings of the study in public meetings and in publications. The findings will provide information that will be useful for improving agricultural management locally and nationally, and will guide future studies in other watersheds.
East Merced Resource Conservation District
Merced River Stakeholders
Turlock Irrigation District
Merced County Dept. of Agriculture
California Central Valley Regional Water Quality Control Board
Joseph Domagalski, Lead Scientist, Lower Merced River and Mustang Creek study (916) 278-3077, joed@usgs.gov
Paul Capel, Team Leader, National study (612) 625-3082, capel@usgs.gov
NAWQA Program http://water.usgs.gov/nawqa
San Joaquin-Tulare Basins NAWQA http://ca.water.usgs.gov/sanj_nawqa/
Dubrovsky, N.M., and others, 1998, Water Quality in the San Joaquin-Tulare Basins, California, 1992-95, U.S. Geological Survey Circular 1159.
The USGS provides reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy and mineral resources; and enhance and protect our quality of life.
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