USGS Washington Water Science Center
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WA220 - Sediment Data for Evaluation of Best-Management Practices in Irrigated Agriculture - Completed FY1983
Problem - Washington State Department of Ecology has made final its "Irrigated Agriculture Water Quality Management Plan" as required under PL 95-217, Section 208. This plan involves the concept of a performance standard to identify problem farming practices or areas. Once the standard has been established, data will be needed to monitor on-farm instream changes in water quality, particularly suspended-sediment concentration. DOE has requested the Survey's assistance in obtaining reliable sediment data.
Objectives - To provide continuous, reliable data on instream suspended sediment, evaluate the effect of on-farm best-management practices on the suspended sediment concentration in receiving streams, and assist the Department of Ecology in determining the correlation between suspended sediment concentrations and settleable solids concentration as measured with the Imhoff cone.
Approach - Stream-gaging stations and automatic sediment samplers will be installed on the four major drains from the area. Suspended-sediment samples will be collected every 4 hours by the automatic samplers and composited daily. Calibration samples will be obtained twice weekly by Survey personnel. Diel sampling will be done 8 times during each irrigation season to determine the range in concentration and correlation of stream discharge with sediment concentration. Statistical analysis will be used to determine how representative the data are of the total sediment yield.
WA207 - A Demonstration of Best Management Practices on Columbia Basin Irrigated Lands - Completed FY1982
Problem - As a portion of the State of Washington's efforts towards compliance with PL 92-500 as related to irrigated agricultural lands, the Sulphur Creek Pilot Study was initiated last year. This was a multiagency effort to reduce sediment effluent from irrigated farm land through application of best management practices. The USGS participated as the monitoring agency. Several deficiencies have been realized as a result of the first year's efforts: (1) the program requests voluntary participation by the farmers which was only moderately successful, and (2) the program is not designed to provide an economic evaluation. A second study is proposed to answer these problems. It will cover a smaller area, a subbasin of about 2,000 acres. The area was chosen for its varied crops, representative soils, good range of slopes, suitability for monitoring, and has been identified as a sediment-problem area. Full participation by farmers is expected as EPA grant monies will provide 70% funding of recommended on-farm improvements. USGS will serve as a monitoring agency, designing an appropriate monitoring scheme for sediment and nutrients.
Objectives - The USGS will determine if, as a result of implementation of Best Management Practices, the basin experiences a significant change in sediment, nitrate, total nitrogen, ortho- and total-phosphorus concentrations, loads, and time distributions. Additionally, the monitoring network will be designed to provide data for (1) computation of Markov Lag-one (day-to-day time dependence) correlation coefficients, and (2) computation of average daily variation (within a day), from which more statistically sound confidence intervals can be computed for all constituents. Results will be compared with those obtained from the Sulphur Creek Pilot Study to assess transfer value of the data and methods.
Approach - Automatic samplers in refrigerated units will be established at the outflow and at one other selected point in the basin. Continuous gaging stations will be installed at these two sites. Sediment and nutrients will be sampled bi-hourly. These will be composited into 1 daily sample, except during storm events. Twelve 24-hour studies will be conducted to determine the average daily variability in each constituent. Headgates will be read daily and rated by several discharge measurements. Sediment and nutrients from the supply canal will be analyzed daily and weekly, respectively. Suspended sediment, total nitrogen, nitrate and total- and ortho-phosphorus data will be tested for definable seasonal variation by harmonic analysis. Particle-size distribution will be determined at the main outflow. Stream temperature will be recorded daily. Mean yearly and seasonal temperatures will be computed by harmonic analysis.
WA195 - Sulphur Creek Pilot Program Evaluation - Completed FY1981
Problem - A pilot program involving Washington State and Soil Conservation Service has been initiated to attempt to abate pollution from irrigation return flows by improving the on-farm management practices in the Sulphur Creek basin. A water-quality monitoring program is needed to ascertain whether the improved farm management practices are effective in reducing sediment and nutrient loads leaving the farms.
Objectives - Determine if there is a significant reduction in (1) sediment concentrations, (2) nitrate and total phosphorus concentrations, (3) stream temperatures; also determine the severity of pesticide contamination in the Sulphur Creek basin.
Approach - (1) Establish sediment and nutrient sample collection sites at significant points of inflow and outflow within the pilot program area, (2) record stream temperature at the time of sample collection, (3) establish and maintain gaging stations on the 5 major drains, (4) establish rain gages to record duration and intensity of precipitation, (5) collect whole-water and bottom material samples for pesticide analysis.