Small streams and some of the most popular destinations in the Iowa Great Lakes found their way on Iowa’s 2010 list of impaired waters, according to John Olson, the DNR’s specialist on water quality assessments.
That doesn’t mean swimmers should abandon Emerson Bay, where higher-than-acceptable bacteria levels were once measured on West Lake Okoboji.
That trip to Big Spirit Lake’s Marble Beach should be fairly safe as well, despite the destination’s place on the 2010 list.
The DNR cited 446 streams, rivers and lakes in need of a water quality improvement plan, including 97 additions to the list. Another 126 waterbodies remain impaired, but are not included on the impaired waters list because they have a completed improvement plan or a plan is not needed, according to the DNR. The agency list counts 572 impaired waters in Iowa.
The higher number on the 2010 list indicates an increase in available water and biological monitoring information, not necessarily an increase in pollution, according to Olson. Waters are considered impaired if they do not meet state water quality standards.
“Most waters in Iowa are not severely polluted,” he said. “But the impairments do indicate that our waters are not as good as they could or should be for aquatic life and for people to swim in, to play in and use as a source for drinking water. It tells us that we, as Iowans, need to act before those problems become severe.”
West Lake Okoboji
Samples that led to a beach bacteria impairment listing at Emerson Bay were collected in 2006, Olson explained.
“These bacteria are not disease-causing bacteria,” Olson added. “They are simply indicator bacteria that occur very commonly in the environment that state agencies like the Iowa DNR use to try to get a handle on the relative risk to swimmers for water-borne disease. That’s the rationale there. The levels at Emerson Bay were above our criteria, so we identified an impairment.”
Olson said hygenics lab researchers ultimately identified a tributary that was delivering some type of run-off water to the lake near that beach. They diverted the water away from the lake beginning in the fall of 2006.
The DNR official also noted a two-year lag between data collection and the release of the impaired waters list. Water quality officials like to have back-to-back biannual cycles where the concerns are no longer present before the lake is taken off the list.
With that in mind, Olson expects West Lake Okoboji will be removed from the 2012 list “and I doubt there’s any problem there currently.”
“We like to make sure the problem is addressed before we pull it off that list,” he said. “That way, we’re not continually flip-flopping back-and-forth as far as listing and de-listing.”
Big Spirit Lake
“I think the problem was a lot more significant at Emerson Bay beach than it was at Marble Beach,” on Big Spirit Lake, Olson said.
Like Emerson Bay, the Marble Beach area reached impairment levels based on bacteria levels in 2006 samples. Follow-up tests in 2007 and 2008 at Marble Beach didn’t reach the same levels of concern.
“This is fairly minor because the last couple of years have not seen any violations,” Olson said. “I would say it would be a candidate for removal from the list in the 2012 cycle … We’re continuing to monitor there and we’ll get another data set and factor that into the next assessment. That said, it was a pretty minor problem.”
The impaired waters list included Center Lake due to high levels of pH, or the measure of acidity in the water. Olson said the findings typically suggest a large population of algae in the water.
The top three reasons Iowa streams are impaired are bacteria, biological factors and fish kills. In lakes, algae, pH levels and turbidity (cloudy water) top the list, according to a statement from the DNR. Lakes and streams may be impaired for more than one cause.
“Personally, I don’t see any yellow flags — any signs of deterioration of conditions,” Olson said of the three Dickinson County lakes mentioned. “I think it’s about what we see across the state. Dickinson County is fortunate to have some of the nicest natural lakes in the state — with Big Spirit, West Okoboji and maybe a couple of others.”
Stoney Creek and Mill Creek
Biological impairments are a major cause of impairment in streams, but are difficult to trace to a specific cause, according to the DNR.
“The streams are are a little bit more problematic,” Olson said. “Sometimes that’s a habitat-related problem. We really haven’t progressed to the point where we’ve been able to really address those issues yet. At this point, we’re really just identifying them, but don’t have an real good process for correcting them.”
Both Stoney Creek and Mill Creek in Dickinson County should have more invertebrates and aquatic insects. The creeks lacked enough organisms to meet a threshold to stay off the impaired waters list.
“We have spent a number of years sampling the fish and aquatic insects in our wade-able streams and we have a pretty good idea of what is expected in the different regions of Iowa as far as what a stream should be able to support by the way of fish diversity and aquatic insect diversity,” Olson said.
The DNR is required to update the impaired waters list every two years. It is submitted to the U.S. Environmental Protection Agency to meet requirements of the Clean Water Act.
Public comment is another part of the impaired waters process — the DNR will accept comments on the list through March 4.
They can be submitted to John Olson, DNR, 502 East Ninth St., Des Moines, Iowa 50319. Or, comments can be e-mailed to John.Olson@dnr.iowa.gov.
A complete look at the draft list and supporting materials are available on the DNR website at watershed.iowadnr.gov/impaired.html. Hard copies are available by contacting Olson at (515) 281-8905.
“I think one message is, we do have some water quality issues that need to be addressed,” Olson said. “A message we have difficulty communicating is that most of these problems aren’t particularly severe. But they do need some attention.”
Russ Mitchell – Editor