The Saskatchewan River

5/3/2009 D. M. Lehmkuhl 1

The Saskatchewan River• The River is impacted by numerous kinds of

pollution and human impacts:

• Dams and Reservoirs

• Pulp Mills

• City Sewage

• Blackfly control and pesticides

• But the river is one of the most unpolluted in North America


In the natural river, the substrate is clean, free of silt, and free of algal or macrophyte growth.

Photo D. Lehmkuhl, Univ. of Saskatchewan


About 20 years ago, raw sewage entered the river from Saskatoon.



Recently, sewage treatment has been upgraded.


5/3/2009 D. M. Lehmkuhl 5Organic debris from sewage outlet, 1970’s.



Natural river sand, with clear water, even when disturbed by footprints.



Caddis fly (Trichoptera) larvae from sewage outlet area, Saskatoon. Note gill areas are blackened.



Mayfly (Ephemeroptera) larva from sewage outlet area.



Stonefly (Plecoptera) larva from sewage outlet area


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Nutrient Pollution

• Recently, the sewage treatment plant has been improved, but it still seems to greatly change the river downstream from Saskatoon. Certainly the growths on rocks and the stringy growths of algae are not esthetically pleasing. Also, the aquatic insect communities are different, at Clarkboro Ferry for example.

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Sewage adds nutrients to the river and there are large growths of algae and macrophytes.


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Masses of plant growth 100 km downstream from sewage outlet.


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Plant growth and silt which result from sewage.


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Abnormal plant growth in net sampler.


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Abnormal algal growth in collecting pan.


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When this material dies, it rots and forms black organic mud. Footprint on sandbar; algal growth and organic mud.


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Abnormal blackening of stones in river.


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Blackened rock, algal growth from 100 km downstream from sewage outlet.


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The Saskatchewan River, the area from F-G is greatly impacted by sewage from Saskatoon. The governmentreport which follows does not agree.

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???

Photos 2000

?




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The sampling done in the governmentreport collected only a small number of known riverspecies.

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Footprints in sand in the normal river.


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Water with black organic mud disturbed by footprints.


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White crust on sandbars, organic mud disturbed by footprints.


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Dams and Reservoirs

• There are several major dams on the Saskatchewan river.

• Dams create lakes, which destroy the river community.

• Dams also change the temperature downstream (Lehmkuhl, 1972)

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Iwate, Japan, PhotosD. Lehmkuhl

Oahe DamS. DakotaPhoto D.Lehmkuhl

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The line above shows that ice covers the river in winter, andwater temperature rises to above 20 C in the summer. Water from the hypolimnion cools water in summer and raises water temperature in the winter (lower line)(Lehmkuhl, 1972).

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Many river organisms need the natural river temperature sequenceto stimulate hatching and growth (e.g. they need freezing temperatures to break diapause). Dams destroy and alterthe natural temperature regime. Organisms are eliminated.

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The number of species is reduced to near zero at the damoutlet. Recovery requires more than 100 KM.

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Rare and Endangered Species• A number of very unusual species of

mayflies live in the Saskatchewan River.

• They are extinct in parts of their former range in the US, as a result of dam construction and pollution. There are now interesting records from Montana and elsewhere

• These rare species still exist in parts of the Saskatchewan river system, but may be eliminated from about 80-90 % of the river.

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Saskatchewan and Glaciation

• About 12,000 years ago, Saskatchewan was completely cover by glacial ice.

• All of the Saskatchewan flora and fauna came from ice-free refugia, mostly from the South, the Southwest, and the Southeast.

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A number of species were known to exist in both the Saskatchewan and Colorado river systems. TheirStatus in the Colorado system is unknown. I surveyed Their status in the Saskatchewan system in 2000.

5/3/2009 D. M. Lehmkuhl 37Mayfly (Ephemeroptera) adult.

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Ametropus neaveiThis mayfly sitson sand substrate, which it grips withthe 4 posteriorlegs, while it filtersfood from the passingCurrent, using fringesone the front legsand mouthparts.

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Analetris eximia is a fast-swimming predator in the larval stage.

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Lachlania saskatchewanensis is also a filter feeder, using the fringes on the front legs, while grasping a root or other Substrate with the 4 posterior legs.

5/3/2009 D. M. Lehmkuhl 41A number of species are distributed from Saskatchewan to the S.E.

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Macdunnoa nipawinia: I described this new species and genusfrom the Saskatchewan River. It is a generalize Heptageniid.

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Pseudiron centralis is a predator which lives onsandbars. It can dig the longclaws into the sand and move rapidly in alldirections, sweeping the sand with the mouthpartsin search of Chironomidprey.

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The Saskatchewan River