Lake Assessment Program - Lake Josephine, Ramsey County

Lake Josephine is located between the Cities of Roseville and Arden Hills in Ramsey County. With a surface area of about 109 acres, it is among the top twenty-five percent of lakes in the state in terms of size. Lake Josephine has a maximum depth of 44 feet, which is a typical depth for lakes of this region. The total watershed is just over one square mile and of this amount, about 65 percent drains through Little Lake Josephine. Land use in the watershed is characterized primarily by urban/residential (92 percent), water and marsh (4 percent), and pasture/open (4 percent) uses. Due to the extremely high urban/residential uses, these percentages are not very comparable to other lake watersheds in this region of the state - North Central Hardwood Forests ecoregion; however, they are typical for lakes in the Twin Cities metro area. Lake Josephine was sampled during the summer of 1998 by the Minnesota Pollution Control Agency (MPCA) staff and citizens from the Lake Josephine Association (Association). Water quality data collected during the study reveal summer-mean total phosphorus (TP) concentration of 30 ?g/L, chlorophyll a of 11.5 ?g/L and Secchi transparency of 6.2 feet. All three measures are within the range of values exhibited by reference lakes in the NCHF ecoregion. Total phosphorus, chlorophyll a and Secchi transparency help to characterize the trophic status of a lake. These measures indicate borderline mesotrophic - eutrophic conditions for Lake Josephine.