Authorities said workers were pumping the material from the stream. The small dead fish were found near the creek’s shore. A call to Harding Middle School was not immediately returned.

DNR spokesperson Kevin Baskins says a citizen reported seeing dead fish and a yellowish color in a creek located at Noelridge Park in Cedar Rapids. It was determined that the yellow substance was coming from a storm sewer located at Harding Middle School in Cedar Rapids. Workers at the school were cleaning up linoleum floors and had been dumping the contents of wet vacs into the storm sewer. Baskins says the stripper/wax solution emptied into the creek killing an undetermined amount of small fish. Workers from the school and the city of Cedar Rapids pumped the material from the stream on Sunday. The DNR has told school officials to purchase separate containers to empty material from the wet vacs. “We’ve advised them to put drums there, pour the material into that and then it can be properly disposed of from there,” Baskins said. The school district or the workers could face fines. “At this point, we’re looking at what would be the appropriate enforcement action,” Baskins said.

The "World's Largest Bullhead" statue was constructed in 1958 by Carl Frick

After years of planning and community involvement, Crystal Lake is at the end of its long road back to becoming the North Iowa treasure it once was. “It used to be one of the great little fishing spots in North Iowa, and soon it will be back to that level,” said Tom Haan, head of the Hancock County Board of Conservation.

The lake has gone through an extensive dredging and renovation process that has been in the works since around 1991, when fundraising efforts began throughout the community. The process has taken nearly 20 years to complete, but is finally reaching its end.

Lake classification reports in 1980 and 1991 identified Crystal Lake as a high priority candidate for lake restoration, and it was placed on the impaired waters list in 1998. Crystal Lake is one of Iowa’s 34 natural glacial lakes and the 269-acre lake has been suffering from organic enrichment due to sediment build up. The lake had been crippled by high phosphorus and nitrogen levels for years before the dredging process began.

A sediment pond was also constructed near the lake and it is estimated to help reduce sediment and runoff delivery to by upwards of 20%.

Before the project began the lake measured just six feet at its deepest point, and through the utilization of a tier effect plan during dredging, the lake now measures 22 feet at its optimal depth. The tier system has greatly amplified the overall volume of the lake, providing waters that measure 22, 18, 12, and 8 feet respectively depending on location.

The estimated $3 million dollar dredging project got underway in the fall of 2006 and was aimed at removing over 1.1 million cubic yards of sediment. A major goal of the project was to restore the lake to more natural depths in support of recreation and to provide a better environment for aquatic life. The dredging was completed in 2007, which effectively removed Crystal Lake from the impaired waters list, however other problems still remained.

During the flood of 1993, an invasion of carp began which led to water clarity issues among other problems. The lake had seen a similar carp overtaking during the early 1980’s, and the fish population was renovated to promote a healthier environment for aquatic life and more appealing sport fishing. Following the dredging, plans were made to once again renovate the fish population.

During the dredging process, the lake was dropped 18 – 24 inches, providing a seal from the West Fork of the Iowa River which headwaters in Crystal Lake.

This seal helped bar a chemical agent from entering the river that was released into the lake during the fall of 2008 in order to kill off the entire fish population.

Over the two decades since the last fish renovation high levels of nutrients and resultant algae had led to periodic low levels of oxygen at the bottom of the lake. This led to the aquatic community of the lake being dominated by species tolerant of low oxygen conditions, like bullhead and carp.

Other more desirable game fish, like bass and catfish, suffer from impaired spawning and reproduction in low oxygen conditions and populations started to decline in the lake.

Also of concern for county and DNR officials were the effects the carp were having on water quality.  The DNR started a stocking regiment earlier this year and has introduced several species of fish back into the waters.

Throughout the spring officials have released northern fry, catfish, bluegill and bass. All the fish were released at a rate of 100 fish per acre, or 269,000 fish per species.

Plans are being considered to stock the lake with crappie as well.

Now all that is left for Crystal Lake is to wait for the fall when the fish will reach a reasonable size to catch, with ideal fishing conditions being established by next summer as fish reach their optimal size.

Later this year the DNR will conduct fishing surveys to check the progress of the aquatic population through utilizing electric shock techniques to stun the fish, capture, and then weigh them.

“We hope people enjoy the lake and take the necessary precautions to help keep it clean,” said Kurt Meek, a fisheries technician for the DNR. “Users should take special attention to cleaning boats and propellers, along with abstaining from introducing other varieties of fish, those kind of efforts would help substantially.”

The lake is prepared to stay at a reasonable level of cleanliness, and a small outlet structure has been renovated to prevent undesirable fish, like carp, from re-entering the lake population ever again.

The local community has the potential to benefit from the lake once again returning to its place among North Iowa’s great fishing locations, and projections estimate that over $400,000 in fishing related revenues could be added to the local economy.

The lake rests beside a 130-acre DNR owned campground, beach, park, and disk golf course that is maintained by the Hancock County Conservation Board and hosts approximately 14,000 visitors annually.

Officials say the kill started on Father’s Day weekend. The IDNR has already re-stocked more than 50,000 young smallmouth bass. More are planned. The Illinois Environmental Protection Agency and the Illinois Attorney General’s office are investigating.

The Rock River feeds into the Missippi River and appears to have stopped about 40 miles before reaching the Mississippi.