Here is an article from 2009 that says channel cats were restocked in 2007 after the lake was treated.
http://www.spokesman.com/stories/2009/apr/12/sprague-lake-trout-lure-i-90-anglers/This one says they put about 60 of the big cats back in after they treated the lake, so there should be a decent bunch in there now.
April 4, 2008
Contact: Chris Donley, (509) 892-1001 ext. 307
WDFW stocking trout in Sprague Lake
OLYMPIA - Anglers have an opportunity to catch fish once again at Sprague Lake, where the Washington Department of Fish and Wildlife (WDFW) is stocking trout for the next several weeks.
The trout plantings are necessary after the 1,840-acre lake, which is alongside Interstate 90 in eastern Washington's Adams and Lincoln counties, was treated with rotenone in October to rehabilitate a declining sport fishery. Carp, tench, walleye and other species were removed after the lake was treated with rotenone, a naturally occurring substance derived from the roots of tropical plants that kills fish but does not hurt people, pets, livestock or wildlife.
"The first fish we're putting back in Sprague Lake are catchable-size rainbow trout from our hatcheries," said Chris Donley, WDFW district fish biologist. "Later this spring, we'll stock crappie, bluegill, largemouth bass and channel catfish that will take a few years to grow and reproduce."
Overall, WDFW will stock about 160,000 catchable-size rainbow trout, including about 3,200 triploid trout that weigh up to 1.5 pounds each, in Sprague Lake over the next two months. Cow Lake, which is part of the Sprague Lake watershed, also was treated with rotenone last fall and will be stocked with about 6,000 rainbow trout.
Approximately 200,000 rainbow trout fingerlings and 80,000 cutthroat trout fingerlings also will be stocked in the Sprague Lake watershed to support future trout fisheries, said Donley.
Later this spring, largemouth bass, bluegill and crappie will be stocked in Sprague Lake. WDFW also will return about 4,000 black crappie and at least 60 channel catfish that were collected from Sprague Lake before last fall's treatment.
Fishing regulations for Sprague Lake, which is open year round, can be found on WDFW's website at
http://wdfw.wa.gov/fish/regs/fishregs.htm .