INTRODUCTION

The Skokie Lagoons are a large waterway system close to my house.  They are about 1 mile from Lake Michigan, and interestingly, they don’t drain into the lake.  Instead, due to a large moraine formed in the last ice age that runs N – S about ½ mile inland from Lake Michigan (called Ridge Road in my town of Winnetka), the Lagoons and the Skokie River which flows through them drain into the Chicago River and then eventually into the Mississippi River system.  It is an interesting geologic feature – and an interesting fact that many of the Great Lakes have very small watersheds.

There is some history on the Lagoons here, https://www.winnetkahistory.org/gazette/swampsecretsskokielagoons/ but basically the Villages of Glencoe and Winnetka drained the large swampy area in the 1940s, by digging out the swamp to create six or seven large lagoons and thus draining some of the surrounding land to make way for new village homes.  I have kayaked and hiked around the area – it is very accessible and pretty!

With my interest in ecology and natural resources and my experience in water quality testing from both Swiss Semester and the Vanderbilt Summer Academy, I thought it would be fun to investigate the Skokie Lagoons!  They are in my backyard.

Here is a link to a map of the system from the Illinois DNR.  https://www.ifishillinois.org/profiles/waterbody.php?waternum=00170, the DNR website shows that a large amount of fish are stocked into the Lagoons.

METHOD AND HYPOTHESIS

The Skokie River and Lagoon system run through a very urban area, including a major highway just west of it.  The system receives heavy pressure from fishing and recreation.  On outward appearance, I would say the Lagoons seem somewhat degraded – highway runoff of oil and gas, urban lawns over-fertilized leaching into the system, and the shoreline is littered by tamped-down fishing trails.  But, part of the Lagoon system runs through the Chicago Botanic Garden – which is a 300 acre “living plant museum” and perhaps helps improve the water quality with its focus on environmental and sustainability ecology.  I knew the Lagoons were not a pristine Swiss stream or even a Tennessee Smokey Mountain creek from my high school adventures. Not sure I’d ever want to swim in the Lagoons, but I wanted to find out where they stacked up on water quality.

With that in mind, I set out to take 8 water quality samples along the shores of the Lagoons and Skokie River system, and 2 baseline samples of my house tap water and water from Lake Michigan at Lloyd Beach.  Testing included dissolved oxygen, pH, phosphates, and nitrates/nitrites.  Samples were taken in knee deep water at several locations, as documented on both my results spreadsheet and the Google maps locations, as shown below.  There had been no rain for the last 5 days.

My hypothesis was “The Skokie Lagoons and the Skokie River which flows through it are below average range for generally accepted water quality”.  This is largely due to my thinking that the presence of large asphalt areas nearby, potentially high nitrates/phosphates from suburban water runoff and the degraded condition of the banks which hamper water filtration make the Lagoon system below average.

FINDINGS

The gold stars are where I took my samples from in the Skokie Lagoon

Sample #4 – Weir Site

Sample #3 testing

I have several interesting results from my water testing. As the above spreadsheet shows, the pH remained fairly consistent whether nearby highway I-94 or farther away from it – leading me to think that battery acid/gasoline/oil runoff is not directly entering the Lagoon system in a large manner.  Phosphates and nitrites also were low and within acceptable limits.  A very interesting finding is that downstream of a Winnetka public works project where they are currently digging out a sort of water retention pond to relieve village flooding, the nitrates reading were high.  I checked this again with testing and the tests were similar.  Above the project location, nitrates were 0 – 1.2 ppm while below the water entrance, the nitrate readings were 15 – 20 ppm.  I suspect the disturbed soil is leaching nitrates into the water.  Dissolved oxygen also was within good limits over most of my samples.  I was a little surprised by this, as decaying plant matter, which seems to be very present in the Lagoon system, uses up available oxygen in the water.  Although, the Skokie Lagoon network has a weir in one spot and also a 5 foot dam at another, so the water does churn and create more dissolved oxygen over its flow southward.

Lastly, as shown below in the picture, on test spots #7 and #8, I found eaten freshwater mussel shells. I suspect a raccoon or perhaps the Great Blue Heron which was carefully watching me at Sample site #7 may have had mussels for lunch.  Mussels are a great sign of water quality as they need stable, within-range dissolved oxygen, and they act as a filtering source!

CONCLUSION AND FURTHER ACTIONS

I would reject my hypothesis that the Skokie Lagoons are a degraded, below acceptable water quality system.

• DO, pH, phosphate, nitrite tests all within acceptable ranges, nitrate below Winnetka retention pond was high although within acceptable ranges. Once the active construction is finished I would expect this to return to similar upstream readings.

• Finding 2 freshwater mussels at Sample Site #7 and #8 very encouraging indicating dissolved oxygen is adequate in the Lagoon System.

Going forward, I would be very interested to test Sample Sites #7 and #8 again for nitrates.  I already tested them after the high nitrate reading initially and got about the same results.  These are the testing sites below the Winnetka water retention project.  I strongly suspect that all the earth moving and land disturbances created a “churn” of organic material that is washing into the Skokie River just south of the last Lagoon.  It would be interesting to test in the spring when the project and land disturbances are done.

I also would like to contact the Chicago Botanic Garden head hydrologist (if they have one!) and ask some questions – Does anyone monitor the water quality in the two Lagoons on their property?  Does the Botanic Garden do anything to improve water quality?  If you look at the map, the first two Lagoons are on their property and maybe they influence the water quality downstream?

Lastly, at my Vanderbilt program we reported our findings to the Tennessee Department of Water Resources.  I will submit a report of my findings to the Illinois Department of Water Resources.

To conclude, I thought this was a fun project to test the water quality of a lagoon system close to my house.  I was surprised to find freshwater mussels, and positively surprised to find that the dissolved oxygen, pH, phosphates, nitrites and generally nitrates were all in acceptable limits – and especially for a fairly urban water system.  The Skokie Lagoons and Skokie River may look a little degraded and mucky, but have surprisingly good water quality!

PICTURES BELOW!

Sample #7 – Winnetka Drainage Work slightly upstream

Sample #2 location

Sample #6 testing

Sample #5 location

Sample #8 - #2 Clam

Testing Lake Michigan