| Section 1 | Overview | |||
| Originator | Natural Resources Research Institute, Minnesota Pollution Control Agency | |||
| Title | Lakes - Clarity - Trends | |||
| Abstract | This data layer indicates trends in lake clarity based on Secchi disk measurements. It was developed by the Natural Resources Research Institute using data from the Minnesota Pollution Control Agency. A Secchi disk measures water transparency or clarity and indicates the amount of light penetration into a lake. Secchi depth also provides an indirect measure of the amount of suspended material, algae or sediment, in the water. The trend analysis, which shows both the presence or absence and direction of a significant trend, was performed using a Seasonal Mann Kendall statistical test. Lake water clarity must change more than half a foot (0.15 meters) per decade to be considered a detectable change, or trend. The analysis was based on 47 years of data (1972-2019). Long-term transparency monitoring provides a cost-effective, valuable basis for detecting trends in water quality. Generally, the sooner water-quality problems are detected, the easier and less expensive it is to restore the lake to its previous state. | |||
| Purpose | ||||
| Time Period of Content Date | ||||
| Currentness Reference | ||||
| Progress | ||||
| Maintenance and Update Frequency | Annually | |||
| Spatial Extent of Data | ||||
| Bounding Coordinates | -97.141765 -89.915627 49.404474 43.440014 | |||
| Place Keywords | ||||
| Theme Keywords | ||||
| Theme Keyword Thesaurus | ||||
| Access Constraints | ||||
| Use Constraints | ||||
| Contact Person Information | Kristi Nixon,
GIS Specialist University of Minnesota, Natural Resources Research Institute 5013 Miller Trunk Highway Duluth, MN 55811 Phone: 218-788-2645 Email: knixon@d.umn.edu | |||
| Browse Graphic | None available | |||
| Associated Data Sets | ||||
| Section 2 | Data Quality | |||
| Attribute Accuracy | ||||
| Logical Consistency | ||||
| Completeness | ||||
| Horizontal Positional Accuracy | ||||
| Lineage | ||||
| Section 3 | Spatial Data Organization (not used in this metadata) | |||
| Section 4 | Coordinate System | |||
| Horizontal Coordinate Scheme | Universal Transverse Mercator | |||
| UTM Zone Number | 15 | |||
| Horizontal Datum | NAD83 | |||
| Horizontal Units | meters | |||
| Section 5 | Attributes | |||
| Overview | ||||
| Detailed Citation | ||||
| Table Detail: | ||||
| lake_trends | |||
| Field Name | Valid Values | Definition | Definition Source |
|---|---|---|---|
| FID | Internal feature number. | Esri | |
| Shape | Feature geometry. | Esri | |
| dowlknum | |||
| pw_basin_n | |||
| acres | |||
| INSIDE_X | |||
| INSIDE_Y | |||
| in_lakefin | |||
| lake_id | |||
| lake_name | |||
| nameformul | |||
| lakename | |||
| loc_major_ | |||
| record_len | |||
| obs | |||
| mean_slope | |||
| mean_p_val | |||
| mean_huc_s | |||
| mean_huc_p | |||
| deta_slope | |||
| lake_ly | |||
| lake_ly_me | |||
| huc8_ly | |||
| huc8_ly_me | |||
| delta_ly_m | |||
| start_date | |||
| simple | |||
| trend_dire | |||
| dow | |||
| dow1 | |||
| ObjectID | |||