funding for this program is brought to you by the arts and cultural heritage fund and the citizens of minnesota [Music] the st louis river it's our past our present and our future the story of this place floats on the current of the st louis river from the headwaters and seven beavers lake through farms towns and settlements through brookston cloquet and the duluth superior harbors my name is emily lachlan i'm a student researcher from fond du lac tribal and community college and i've lived by the st louis river my entire life industrial expansion built burgeoning communities businesses in the estuary provided growth jobs and in many cases created havoc with the natural environment my name is joel hoffman i'm a supervisory research biologist for the u.s epa's office of research and development we have a laboratory in duluth so i have spent um a good part of the last 15 years studying the history of the st louis river understanding the pollution impacts to the river and working to understand what we need to know to clean it up what we know or have been able to infer from the data that we have from the early 1900s 1920s and 1940s is that somewhere between 1905 and 1906 and 1920 the river became extremely degraded the first run of walleye moving in from lake superior to the st louis river failed around 1908 which is our first good indication the water quality had become very poor i mean such that the fish you know turned around to leave the area and we know that by the early 20s the lake sturgeon were basically gone all aquatic life needs to breathe many of those organisms need to breathe underwater right like fish that have gills and so they're extracting the oxygen they need to breathe from the water so when we take oxygen out of the water it stresses those organisms it'd be like you or me not being able to breathe we become very stressed that was the key element here in many ways was was that the oxygen was very very low in these areas they went to go look for living organisms in the bottom of spirit lake and couldn't find any so we know by the time we hit into the mid-20s there is an extensive what we call dead zone that is stretching between somewhere around fond du lac probably into and around grassy point and st louis bay so near the heart of the city of duluth and the heart of superior so this was really a large persistent and regular dead zone within the st louis river the scientific term is called biological oxygen demand it was a measure of how much oxygen the pollutants were putting into the river would consume and it was often used for sewage because in this era we did not treat sewage it was held in ponds on the side of the river i mean those ponds were not very well contained and so when big rain events happened they routinely spilled into the river um with either you know partially processed or essentially raw sewage going into the river and so that material had a very high biological oxygen demand bacteria in the waste needed oxygen to live and it would it would consume it and it would consume it so fast it couldn't be replaced and then the aquatic organisms in the river the bugs the fish wouldn't have any oxygen to breathe in that same era we had many pulp mills and other facilities that produced waste that was organic and because it was organic it was going to break down in the river of a bacterial component that was going to consume oxygen as part of that process and so there were many other kinds of waste that were also being put into the river directly without treatment that had a hot very high biological oxygen demand on all of which we believe contributed um to this a long-term dead zone in the river our records from the state show that there is routinely low oxygen all the way through the 60s and by the time we got to the late 60s early 70s it had started to get a bit better so we can imagine that probably the worst of the impacts based on the data we have occurred from around 1905 1908 to probably around 1965. the rivers come a long ways back the scientists and the managers are still working on restoring it the job is not done if you think about it we spent we'll call it 60 years with a part of the river that was dead that's that's hard for us to imagine today but we are now another you know a human generation 30 more years into recovery and we're starting to see a lot of good things happen you are the keepers of this dynamic ecosystem on the water trail begins to uncover this new chapter with science and a deeper appreciation of the river and its mysteries the wildlife plants and history are part of the story as residents of the st louis river watershed you are too [Music] programming is supported by western lake superior's sanitary district innovating solutions and reducing mercury pollution in the st louis river through research and community programs online at wlssd