Chapters 1 - U.S. Fish and Wildlife Service

Chapter 5
Spray applications will not be conducted on days with >30% forecast for rain within six
hours, except for pesticides that are rapidly rain fast (e.g., glyphosate in 1 hour) to
minimize or eliminate potential runoff.
A complete list of the BMPs to be implemented on the Refuge is provided in Section 5.0 of the draft
IPM Plan (Appendix C).
In some cases (as described in the Environmental Fate discussion found in Section 7.6 of the draft
IPM Plan [Appendix C]), product specific BMPs must be implemented to ensure that impacts to
water quality are not significant. For example, to minimize the potential for groundwater quality
degradation as a result of leaching and/or surface runoff, a pesticide with a soil half life or aquatic
persistence half life of more than 100 days would only be approved for use on the Refuge if one or
more of the following BMPs are implemented: 1) limiting application of a particular product to one
application per site per year; 2) not using a particular product on coarse-textured soils where the
groundwater table is less than 10 feet below the surface and the average annual precipitation is
greater than 12 inches; and/or 3) not using a particular product on steep slopes if substantial
rainfall is expected within 24 hours or the ground is already saturated. The same BMPs are
required if the soil or aquatic dissipation time (DT 50) (i.e., the time required for 50 percent of the
deposited pesticide to degrade and move from a treated site) for a proposed product is greater
than 100 days.
The potential for a pesticide to move to groundwater is another factor that is considered in the
PUP approval process. This potential is determined using the Groundwater Ubiquity Score (GUS)
(refer Section 7.6 of Appendix C for more information about GUS). Where GUS is greater than
4.0, a PUP will only be approved with additional BMPs implemented specifically to protect water
quality. These are the same BMPs described above for soil half life and DT 50.
Based on scientific information and analyses documented in the “Chemical Profiles” in the IPM
Plan, pesticides allowed for use on refuge lands would be relatively low risk to surface and
groundwater quality as a result of low toxicity or short persistence in the environment, and/or the
implementation of general and pesticide specific BMPs. The risks to water quality of particular
pesticides presented in Table 5-2 is derived from pesticide product labels and the Pesticide
Properties Database (PPDB 2009) developed by the Agriculture & Environment Research Unit of
the University of Hertfordshire http://sitem.herts.ac.uk/aeru/footprint/en/index.htm.
As described above, additional BMPs may be required for certain products proposed for use on the
Refuge. The following specific BMPs are identified in the Chemical Profiles for the use of
glyphosate and oryzalin:
Glyphosate: Apply aquatic labeled or surfactant free glyphosate formulations to aquatic
habitats and riparian habitats within 25 feet of surface water resources.
Oryzalin: Allow one application at 1.5 pounds of active ingredient per acre per year;
maintain a minimum 25-foot buffer zone between all upland treatment site(s) and the high
water mark of the nearest surface water resource(s); and avoid the application of oryzalin
to sites that are upslope of any surface water resources when the slope gradient is greater
than 17 percent.
No specific BMPs are required for the use of products containing the active ingredient imazapyr.
5-18 Seal Beach National Wildlife Refuge