------- REPORTED SILVICULTURAL PESTICIDE USE IN CONTINENTAL UNITED STATES, 1972 flcies - Insecticides Fun ;icides 2 82,2821acres .Marcel acres treated 54,920 acres treated ,854 freas/reated (Sufnmar ized front tj.S. forest Servicefces- ticifies use JTptirts and a National FqrestJpTO- dufts Association survey representing approx- imately 32 million acres, vfill fluctuate greatly fr#n year to year. <¦ \ v hi H Aft ¦¦ J0T ------- US EPA and Chemical Libraries -t,?9t Bldg Room 3340 /lailcode 3404T ji Constitution Ave NW inington DC 20004 202-566-0556 % > INTRODUCTION There are approximately 0.5 billion acres of commercial forest lands in the United States. Chemical application to the forest land for en- hanced production has fluctuated widely from year to year; however, as many as 2 million acres may receive one or more forms of chemical treatment in any given year. mb Three general groups of chemicals are used, all of which might result in significant water pollution o if application procedures are not carefully con- ^ trolled. The categories are: fertilizers (for in- creased fiber production), herbicides (for species selectivity), and insecticides and rodenticides (for pest control). ------- EPA Region X has recently published a detailed report, "Silvicultural Chemicals and Protec- tion of Water Quality." The report presents a general description of chemical use in silvicul- ture, provides criteria for limiting concentra- tions of chemicals in water, identifies chemical behavior and establishes pollution control guidelines. Ordering information for it and re- lated publications is given in the back of this brochure. This brochure is intended to touch on best management practices in forest chemical application. Procedures are presented that will better assure meeting the mandates for both environmental protection and high commodity production in America's forests. ------- ------- APPLICATION METHODS Aerial application by airplane or helicopter is by far the dominant method of chemical appli- cation. ------- msmsi Ground application of all classes of forest chem- icals has traditionally involved small amounts of chemical at such distances from open water that possible detrimental impacts on streams are less than those of aerial application. ------- ENVIRONMENTAL CONCERNS Toxic Chemicals Many of the forest chemicals have toxic proper- ties even at low concentrations. The miminum dose necessary to produce a measurable effect (threshold dosage) in an organism will vary con- siderably from chemical to chemical. The toxic hazard of a chemical is dependent not only on dosage but also on (1) level of exposure, (2) duration of exposure, (3) route of contact, and (4) absolute toxicity of the compound. The con- centration of a toxicant has a direct effect on aquatic organisms only in relation to the amount absorbed and the period of retention. ------- Nutrient Enriching Chemicals A toxic impact from fertilizers would generally require extremely large application rates. The primary concern for improper use of these chemicals is excess nutrient enrichment of sur- face waters due to either runoff or direct appli- cation to streams and lakes, resulting in heavy aquatic weed growths or stimulation of other aquatic organism growth that could lead to oxy- gen depletion, fish kills, and related problems. ------- NATURAL INFLUENCES ON IMPACTS Generally, the nature of forest chemicals and accepted application procedures preclude ex- cessive transport of the chemicals within a watershed. However, there are several factors related to climate and physical characteristics at the point of application that may influence the extent of impact. These include: Nature and distribution of precipitation Torrential rain soon after application of water soluble chemicals will generally re- sult in polluted runoff. Low intensity, in- termittent rain several weeks after applica- tion will have little pollution effect. Length and steepness of slopes This is generally of limited concern in forested areas because of ground cover ef- fect on retention of runoff; however, steeper slopes will increase potential im- pacts where cover is light or increased sur- face runoff occurs. Nature and distribution of ground and sur- face water Forest waters will often show higher levels of pollution in nearby flat areas where water tables approach the surface and small streams or swamps are numerous. Contamination can occur because of the difficulty in avoiding aerial application to water. ------- '* ,r> ^ k ' * X Tffl ''¦-.v£ t -~/''7'\-\ t v. \ ' .lit s& ***«*» t* < ¦p^ *N»^rsv jga / .1 ¦ WW 5 5> # f r-*/ */ / -l3 /; -, / * £; t ------- Nature of soils Pesticides that persist long enough to be washed from vegetation and through the forest floor material may be (depending on the type of pesticide) adsorbed onto the surfaces of the smaller soil particles, where a large variety of micro-organisms are capable of decomposing many of them. As long as groundwaters are not close to the surface, high soil porosity can improve the results of this process. However, water may move through very highly porous soils so rapidly that there is little opportunity for adsorption or microbial degradation. ------- Other natural influences Extent of streamside cover vegetation, water depth at point of contamination, stream bottom characteristics, stream vel- ocity, degree of aeration in the stream, suspended sediments in the stream, water temperature, availability of dilution water below the point of contamination, sensitiv- ity of the aquatic community to the chemi- cal being applied these and more influences can determine the relative im- pact of a chemical application. ------- \ I SEVERAL FACTORS 1 THAT CAN AFFECT THE DEGREE 1 OF CHEMICAL IMPACT I Increased Impact Decreased Impact 1 Steep slopes Infrequent application ¦Disturbed soils Continuous ground cover I Application upstream 1 from water users High water dilution rates ¦ Frozen soil during I spring runoff Low percentage of area treated iThin soils Porous soils Minimum surface runoff J The graph that follows shows pesticide concen- tration in a stream after 10% of a watershed was ------- sprayed. It points out how quickly the concen- tration can decrease given certain stream condi- tions and selected application techniques. Curve for sampling at lower end of project Curve for sampling several miles downstream application (hours) ------- APPLICATION CONSIDERATIONS Chemical and Environmental Characteristics Insecticides require greater safety measures than herbicides since acute insecticide toxicity tends to cause direct and immediate injury to aquatic and other non-target organisms. Chronically toxic materials (e.g. the persistent insecticides) require greater safety measures also to insure against long-term effects. Small streams (less than 10 c.f.s.) cleanse more rapidly and will tolerate a given peak level of contamination more readily without major harm than will a larger stream. Because large streams cleanse more slowly and more biological communities are exposed, the larger the stream the greater the needed safety measures. ------- Operational Considerations Some state forest practices acts require the isola- tion of treatment areas from open water. The effectiveness of a buffer strip in minimizing pollu- tion is dependent on application droplet size, basic swath width, and degree of precision in control of the aircraft. It is necessary to: Maintain control over the proximity of the ap- plication to the stream. Maintain control over the choice of chemical, hence the probability for an application rate to cause damage. Maintain control of the dispersion from appli- cation equipment. Technical Considerations An important control factor is to minimize fine droplets that may be widely dispersed in a 1 to 10 mph wind during chemical application. This can be accomplished in several ways: Reducing boom pressure. Increasing orifice size. Orienting nozzle into air stream. Using specialized boom and nozzle designs. Minimizing straight oil in spray mix. Using spray adjuvants to thicken spray mix. ------- Management Considerations Substitute less harmful practices when operat- ing in streamside buffer strips. Restrict general use of organochlorine insec- ticides. Train and license chemical applicators. Eliminate picloram and dicamba chemical res- idues in water used for irrigation. Monitor silviculture applications to be certain both that recommended doses and application procedures are being followed and that these are effectively maintaining water quality. ~ GPO # 796-221 ------- For further information <|he following reports are available: 1. "Silvicultural Chemicals and Protection of Water Quality" EPA 910/9-77-036, June 1977, through NTIS, PB 271923/AS, ($8.00) Springfield, Virginia 22161. 2. "Forest Harvesl forestation and Prof EPA 910/90^ NTIS, PB 253; Virginia 221* Treatment, Re- jon of Water Quality" April 1976, through ($9.25) Springfield, 3. 44 Forest Harvesting and Water 625/5-76-013, available free of Transfer, U.S. EPA, R5hjoj5268. (18 page brochure] 4. "Logging Roads and Protects I Quality* EPA 910/9-75- through NI LS, l^A 24370.4 Springfield, ,99 EPA from i ti. Water -ch 1975, ($9.75) 5. "Logging Roads aAdBVater Quality" EPA 625/5-76-011, available free of charge from Technology Transfer, /U.S. EPA, Cincinnati, Ohio 45268. (18 pagci brochure) PREPARED BY HE ENVIRONMENTAL PROTECTION AGENCY REGION X 1200 6th AVE. SEATTLE, WASHINGTON 98101 PHOTOGRAPHS COURTESY OF U.S. FOREST SERVICE AND E.P.A. ------- TECHNOLOGY m m. m 1 ¦ m v v V * il TRANSFER «s> £ % <7 L . . . > A ? hOMK/f lu *r o * W ENVIRONMENTAL RESEARCH INFORMATION CENTER \ PR01<-C ------- |