http://www.ext.colostate.edu/pubs/crops/xcm175.pdf

"Site characteristics such as land slope, surface residue,
and proximity to surface water must be used to determine
which management measures are needed to protect surface
water from P enrichment from manure. In some cases, sites
with excessive slope or highly erodible soils are not suitable
for manure application, even with careful management. Application
of manure on frozen or wet soils subject to runoff is
not recommended.
Runoff from feedlots and manure stockpile sites also
can contribute nutrients to nearby surface waters. These
facilities should be managed to divert or minimize the total
runoff as required by Colorado and federal laws. BMPs to
reduce runoff impacts include use of yard shaping, settling
basins, diversions, and filter strips (Table 3)."

http://www.ie.unc.edu/for_students/courses/capstone/04/Storm...

"Agricultural components of runoff contribute a variety of pollutants to waterways including nutrients, pesticides, and suspended solids and comprise the largest category of NPS pollution"

http://www.hermosabch.org/index.aspx?page=409

"8.44. 020 Findings
A. The Congress of the United States (hereinafter "Congress") has determined that pollutants contained in storm water and urban runoff are responsible for the environmental degradation of oceans, lakes, rivers, and other waters of the United States.
...
"Area susceptible to runoff" means any surface directly exposed to precipitation or in the path of runoff caused by precipitation which path leads off the parcel on which the surface is located.
...
"Runoff" means any runoff including storm water and dry weather flows from a drainage area that reaches a receiving water body or subsurface.
...
4. Discharges of untreated runoff to the MS4 from storage areas of materials containing grease, oil, or other hazardous substances (e.g. motor vehicle parts), and uncovered receptacles containing hazardous materials;
...
B. Storm water runoff containing sediment, construction materials or other pollutants from the construction site and any adjacent staging, storage or parking areas shall be reduced to the maximum extent practicable.
...
With the consent of the owner or occupant or pursuant to an inspection warrant, any authorized enforcement officer may establish on any property such devices as necessary to conduct sampling and monitoring activities necessary to determining the concentrations of pollutants in stormwater and/or non-stormwater runoff. The inspections provided for herein may include but are not limited to:
1. Inspecting efficiency or adequacy of construction or post construction BMP's;
2. Inspection, sampling and testing any area runoff, soils in areas subject to runoff, and/or treatment system discharges; "