1. Whether the Clean Water Act exempts from
its National Pollutant Discharge Elimination System
("NPDES") permitting program "discharges composed
entirely of return flows from irrigated agriculture" as
the statute expressly provides (33 U.S.C. § 1342( l)(1)),
or instead exempts "irrigation return flows that do not
contain additional point source discharges from activities
unrelated to crop production," as the Ninth Circuit
interpreted the exemption to mean in this case? (App.
21-a.)

2. Whether the Clean Water Act's exemption from
its NPDES permitting program of "discharges composed
entirely of return flows from irrigated agriculture" (33
U.S.C. § 1342( l)(1)) exempts dispersed pollutants from
non-farm sources that are collected and commingled with
agricultural return flows before their discharge to waters
of the United States?

3. Whether this Court's ruling that under the
NPDES permit program "a point source need not be the
original source of the pollutant; it need only convey the
pollutant to 'navigable waters'" ( South Florida Water
Management Dist. v. Miccosukee Tribe of Indians , 541
U.S. 95, 105 (2004)) applies to the Clean Water Act's
exemption of "discharges composed entirely of return
flows from irrigated agriculture"?

Whether the Clean Water Act exempts from its National Pollutant Discharge Elimination System permitting program discharges composed entirely of return flows from irrigated agriculture as the statute expressly provides, or instead exempts only irrigation return flows that do not contain additional point source discharges from activities unrelated to crop production