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Home , Carbofuran, Chloramben, Quinclorac

U.S. Department of the Interior National Water-Quality Assessment Program NAWQA U.S. Geological Survey Summary of Data Collected on West Fact Sheet Prong Old River near Dayton, Texas, March to September 1994

The Trinity River Basin study-unit The study area covers about 25 square assessment began in October 1991, with 2 miles. It has a network of water-delivery 2.4,5-T 2,4-D years dedicated to planning, analyzing canals and channelized waterways for 2,4-DB existing information, and designing data- improved drainage. Because of the flat collection networks, surveys, and studies. topography, canals, waterways, and roads, Atrazine, Desethyl- Then, a 3-year intensive data-collection the natural drainage area and pattern have program was initiated. The assessment Bromacil been greatly altered. Land use in the study followed guidelines provided by the Butylate area is mostly cropland with approxi­ National Water-Quality Assessment mately equal amounts of rice, sorghum, (NAWQA) Program National Synthesis DCPA , and hay. Other major land uses Dacthal, mono-acid- team and considered suggestions made by include turf farms and pasture for raising the study unit's liaison committee. One of Dichlobenil cattle. Population is estimated to be less the issues selected for study concerned Diethylanaline than 500 and distributed throughout the the quality of runoff in the coastal prairie. Diuron study area. EPTC The study includes collecting streamflow, Ethalfluralin Fenuron water-quality, and watershed data on three Fluometuron The application of in the streams, each representing watersheds in watershed is dominated by the use of her­ MCPA MCPB different parts of the coastal prairie. This bicides on rice crops. The most com­ fact sheet presents a summary of the pes­ monly used herbicides are thiobencarb Molinate ticide data collected on West Prong Old Napropamide (Bolero (trade name)), Neburon River from March to September 1994. Norflurazon (Facet), molinate (Ordram), bentazon Oryzalin Peculate Description of Study Area (Basagran), , and 2,4-D. The rice Pendirnethalin crop also is treated with fungicides such Prcmeton The study area is the West Prong Old Pronamide River watershed that is located west of as benomyl (Benlate), propiconazole PropachJqr Propanil Dayton, Texas. The watershed is flat, has (Tilt), and iprodione (Roveral). A variety Propham Silvex (2,4,5-TP) clay-rich soils, receives an average of 52 of herbicides are used on hay and turf inches of rain each year, and has a sub­ farms; along rights-of-way for roads, Terbacil Thiobencarb tropical climate. These features are char­ canals, and waterways; and near resi­ Triallate acteristic of the coastal prairie in dences on lawns and gardens. Some Triflurahn southeast Texas. such as (Sevin), INSECTICIDES Aldicarb Sulfone Aldicarb Sulfoxide Azinphos, Methyl- Carbaryl Carbofuran Carbofuran, 3-Hydioxy- DDE, p,p- Dicldrin Ethoprop HCH, alpha- HCH, gamma- , Ethyl- Parathion, Methyl- . cis- Propargite

EXPLANATION 0 10 20 | Detects NUMBER OF SAMPLES

No Detects

Figure 1. Location. Figure 2. Pesticide detections. malathion, and diazinon are used near res­ and June to once per month in July. Summary of Pesticide Data idences, on cattle, and on rice crops. Stream-stage measurements were made Two laboratory methods are used for Data Collection three times per week from April to Sep­ analysis of pesticides. One is known as tember. Field measurements during sam­ Gas Chromatography/Mass Spectrometry One water-quality monitoring site was pling include stream stage and discharge, (GC/MS) and the other as High Pressure established on West Prong Old River, at Liquid Chromatography (HPLC). Both the downstream end of the study area. water temperature, pH, dissolved oxy­ gen, and specific conductance. Laboratory of these methods have a variable detec­ Sampling began in March 1994 and will tion level which varies by compound and analyses include major inorganic ions, continue for 1 year. Sampling frequency from sample to sample but commonly is ranges from four times per month in May nutrients, sediment, and pesticides. near or slightly below 0.01 microgram per liter. These methods identify and deter­ mine the concentrations for about 80 HERBICIDES pesticides. However, other pesticides are 10 being used in the study area, including the 1 commonly used quinclorac . 0.1 r - ATRAZINE Herbicides detected in at least half 0.01 the samples include atrazine, desethyl-

0.001 atrazine, metolachlor, molinate, 10 simazine, and tebuthiuron. No insecti­ r METOLACHLOR cides were detected in about 70 percent of " the samples. ' X':-::' The greatest number of detections and the highest concentrations of pesticides were for samples collected in May, June, and July. Molinate, a herbicide commonly used on rice, had the highest concentra­ tions, 10 micrograms per liter, in June. Carbofuran, an , was detected at more than 1 microgram per liter in June. INSECTICIDES The U.S. Environmental Protection Agency (USEPA) has set the Maximum CARBOFURAN Contaminant Level (MCL) for drinking water for atrazine at 3 micrograms per liter and for carbofuran at 40 micrograms O O 00 00 per liter. Concentration of atrazine in 0.001 early March was the only one that 10 exceeded these levels. No MCL values 1 have been set for metolachlor, molinate, 0.1 or diazinon; nor has USEPA set ambient ":-S¥S:S;fflSK:SB:.S.:^ . water-quality criteria for aquatic organ­ 0.01 O y;i;!;:;:;:;:;i:P:: :::"" o ; O OO o "o To "If a -^^-m, . ::. isms for these five pesticides in freshwa­ 0.001 ter or salt water. Q 400 Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Gov­ ernment. y m u ° MAR APR MAY JUN JUL AUG SEP For more information, please contact: 1994 Project Chief EXPLANATION Trinity River Basin NAWQA Study Detects U. S. Geological Survey o No Detects 8011 Cameron Road Figure 3. Selected pesticide concentrations and stream discharge. Austin, Texas 78754-3898

February 1995 FS-142-95