Sentinel Lakes Program: Water quality monitoring and assessment

1. Sentinel Lakes Program: Water quality monitoring and assessment Steve Heiskary, Research Scientist III Environmental Analysis and Outcomes Division Minnesota Pollution Control Agency

2. Outline • Lake assessment approach • What do we know about these lakes? • Data analysis examples – variability and trends; • Plan for 2008-2009; • Collaboration with MDNR staff on reporting • Summary

3. Proposed Sentinel Lakes: MPCA data & reporting summary

4. Sentinel Lakes Baseline Monitoring effort • Split effort between summers of 2008 and 2009 (need to coordinate with other MPCA monitoring priorities); • Anticipate baseline reports for 2008 lakes ready by spring 2009 and 2009 lakes by 2010; • MPCA staff take lead in monitoring and report writing; • Monitoring coordinated with area fisheries office and other local partners as appropriate;

5. Trends and Inter-annual Variability • Provide some simple analysis of trends and variability in trophic status for select lakes; • Note the need for good quality data & potential problems when mixing data from several laboratories; • Example of sediment-diatom inferred TP as a basis for assessing trends

6. Hill Lake, Aitkin County. Example of apparent trend (total record) & variability (recent record). Large break in record. Transparency consistently lower in South Basin.

7. Lake Peltier – Rice Creek Chain: Anoka County. No trends & modest variability over time, ~0.24 m on average (26% of long-term average)

8. Lake Carlos – Douglas Co.: Assessing trends & year-to-year variability: No trend in TP, however variability is high. Is this real or a function of laboratory detection limits, multiple labs, outliers???

9. Portage Lake – Hubbard County: Increase in TP & decline in Secchi in recent years

10. St. Olaf Lake – Waseca County: High variability in Secchi for a small lake – 23% on average (typical 10-20%). [Residuals are long-term mean- annual mean.]

11. Lake Shaokatan, Lincoln County: Use of sediment cores & diatom reconstruction of TP

12. Sentinel Lakes additions: • April-October, monthly • Add cations and anions • Work with Fisheries for up to date characterization of the fisheries & management; • Work with Waters to describe water level record & trends; • Macrophyte assessment? • Trends: Secchi, TP & chl-a based on existing data, characterize variability; • Modeling – MINLEAP & BATHTUB as appropriate • Provide recommendations for frequency of monitoring & other data needs for lake.

13. Summary • Reviewed proposed Sentinel lakes & data availability for each. Lakes selected range from Carlos and Peltier with data collected over the course 20-30 years to Net & Northern Light for which we have no data – Implications as we move forward? • Trend analysis will require extensive attention to quality assurance of data & ideally a single laboratory will be used for this work; • MPCA (Lakes & Streams Unit) proposes to sample each of the sentinel lakes over the course of one open-water season (April – October) during 2008 – 2009; • We will integrate this work with our projected (mandated) monitoring activities and with existing budget & staff; • We will write LAP-type reports that will serve to provide a baseline for each of the lakes; • These reports will provide a sound basis for deciding the frequency & intensity of future monitoring, which candidates may be best for more detailed analysis, and should serve to help shape future proposals for the Sentinel Lakes program. • Successful implementation of the Sentinel Lakes program will require having a clear vision of purpose, communicating that vision and developing extensive partnerships.