  The Makani galaxy hosts the poster child of a galactic wind on scales of the
circumgalactic medium. It consists of a two-episode wind in which the slow,
outer wind originated 400 Myr ago (Episode I; R_I = 20-50 kpc) and the fast,
inner wind is 7 Myr old (Episode II; R_II = 0-20 kpc). While this wind contains
ionized, neutral, and molecular gas, the physical state and mass of the most
extended phase--the warm, ionized gas--is unknown. Here we present Keck optical
spectra of the Makani outflow. These allow us to detect hydrogen lines out to r
= 30-40 kpc and thus constrain the mass, momentum, and energy in the wind. Many
collisionally-excited lines are detected throughout the wind, and their line
ratios are consistent with 200-400 km/s shocks that power the ionized gas, with
v_shock = $\sigma$_wind. Combining shock models, density-sensitive line ratios,
and mass and velocity measurements, we estimate that the ionized mass and
outflow rate in the Episode II wind could be as high as that of the molecular
gas: M_II(HII) ~ M_II(H_2) = (1-2)x10^9 Msun and dM/dt_II(HII) ~ dM/dt_II(H_2)
= 170-250 Msun/yr. The outer wind has slowed, so that dM/dt_I(HII) ~ 10
Msun/yr, but it contains more ionized gas: M_I(HII) = 5x10^9 Msun. The momentum
and energy in the recent Episode II wind imply a momentum-driven flow (p
``boost" ~ 7) driven by the hot ejecta and radiation pressure from the
Eddington-limited, compact starburst. Much of the energy and momentum in the
older Episode I wind may reside in a hotter phase, or lie further into the CGM.
