In today's print edition, we report the U.S. Forest Service's predictions -- and note EPA's criticisms of them -- that streamflow in Davidson Canyon and Cienega Creek will not be seriously reduced by the Rosemont Mine.
But in its latest environmental review of the $1.2 billion open pit copper mine, the service does conclude that it will have some negative impacts on downstream springs and riparian areas.
Here are some predictions from the preliminary draft of the service's final Rosemont environmental impact statement:
-- Mine construction would lead to direct disturbance of 588 acres of riparian areas. This would affect washes on the mine site containing what's known as xeroriparian habitat. They are typically lined by cacti and other desert plants rather than the cottonwood and willow trees along hydroriparian areas or mesquite, sycamore and ash found along mesoriparian areas.
-- Indirect impacts on 162 acres of Barrel Canyon riparian areas are expected with "high certainty," due to reductions in streamflow or groundwater level declines caused by the mine. Barrel Canyon leads directly from the mine site to Davidson Canyon.
-- Indirect impacts on 407 acres of Empire Gulch riparian areas are possible, but "highly uncertain." Empire Gulch is a tributary to Cienega Creek.
-- Indirect impacts on 502 acres of Davidson Canyon riparian areas are expected "with moderate certainty."
-- No indirect impacts on riparian areas are expected in Cienega Creek, Gardner Canyon or Lower Davidson Canyon.
-- Another 13 riparian areas associated with springs are fairly certain to be directly or indirectly impacted. Another 36 riparian areas associated with springs could be indirectly disturbed, "but with lower certainty."
-- Five springs are likely to be lost to surface disturbance. Eleven more are likely to be indirectly impacted due to groundwater level declines.
-- Sixty springs may be indirectly impacted due to groundwater level declines. They lie in areas where the mine is expected to lower the water table by up to five feet, although the springs' actual water source is unknown.
-- Nineteen springs are unlikely to be damaged.