Presentation on theme: "Peter Sigmann Little Sturgeon Area Property Owners Association Tracking Phosphate in Little Sturgeon Bay Location The Bay of Little Sturgeon is located."— Presentation transcript:
Peter Sigmann Little Sturgeon Area Property Owners Association Tracking Phosphate in Little Sturgeon Bay Location The Bay of Little Sturgeon is located about 10 miles west of Sturgeon Bay, WI. It is about 1 mile wide where it joins the Bay of Green Bay. Water sampling locations are noted on the map. Water depth at the “outer bay” location is 16’, at the “east bay” and “west bay” locations the depth is 6’. We began scheduled water sampling in our bay in This sub-area of Green Bay is important for the spawning and hatching of much of the area’s fish. Increasing growth of invasive aquatic species and of cladophora threatens this environment and the property values. Methods Our water testing includes checks for phosphate, nitrate, oxygen content and water clarity. Significant findings were limited to phosphate concentrations. Testing was done monthly from April to November from 2001 until 2009 when the frequency was doubled. Samples are obtained from the surface and tested with Hach PhosVer 3 reagent and color disk comparison. The procedure is EPA approved and covers concentrations of mg/L. Beginning in 2009 we used equal-volume dilution to determine values that exceed 5.0 mg/L Results Introduction High phosphate concentrations occurred in the outer bay intermittendly from 2003 to early Spot checking suggested that the littoral current of Green Bay was the source. Beginning in 2008 we recorded intermittend elevations of phosphate at the back-bay locations with increasing frequency. Additional sampling on subsequent days indicated that these elevations were of short duration. Sampling closer to shore and at the mouths of feeding creeks showed less phosphate content/ Creek Monitoring 2009/10 Little Sturgeon watershed: Most readings were zero or less than 2 mg/l of phosphate, but occasional elevated values of 3, 3, 3, 4 and 7.4 mg./l phosphate were recorded. Adjacent watersheds: Occasional elevated readings of 2.8, 3.5,3.7, 7.2 and 10 mg/l phosphate occurred in summer and fall. Reference Laboratory Testing Duplicate samples were sent to the Wisconsin State Laboratory in October 2009 at a time when none of the bay sampling sites yielded high values. The specimens were assayed for Total Phosphorus (as P) and ranged from 11 to 16 mcg/L at the bay sites and 17 to 85 mcg/L in the creeks feeding the bay. Bacteriologic Testing Samples from the four feeding streams were analyzed at the Wisconsin State Laboratory on one occasion in the fall of All showed E.coli at 4 to 5 colonies/100 ml/ Discussion We have observed several trends: Phosphate in the outer bay has a diminishing tendency Intermittend very high phosphate readings in the East and West bays are becoming more intense and frequent. These elevations appear highly localized and may suggest submarine springs as source of phosphate discharge. Other observations: Large volume applications of cattle farm sewage take place in the watershed. The Little Sturgeon watershed has typical karst characteristics which would allow rapid entry into the superficial and deep aquifers of liquids rich in phosphate. Next Steps Explore sample collection from lake floor at the standard sampling sites Bi-weekly bacteriologic testing Hydro-geologic evaluation to determine possible input sites to groundwater Continue ongoing monitoring schedule Questions or Suggestions? Contact Peter Sigmann Ground Water Testing 12 domestic wells surrounding the bay were tested for phosphate. Significantly elevated values were found in three.