Overview of Water Quality Monitoring in

Chris Teichreb, M.Sc., P.Biol. Alberta Environment, Red Deer

• Approximately 2 times size of Pigeon Lake (187km2 : 96.7km2) • Drains through Pigeon Lake Creek into (height controlled by weir) • Numerous summer villages, one Indian reservation, and one provincial park • Surrounding land consists of agricultural and forested areas Pigeon Lake

• Large, relatively shallow basin with max. depth of 10.1m • Water levels have typically fluctuated around 1m over the years – typical of lakes

Water Quality • Sampled in 1969-1975 by U of A • Sampled in 1981, 1983-1999, 2002, 2003, 2005, 2006, 2007 (winter sampling only), 2008 and 2011 by AENV • Sampled in 2001 and 2010 by ALMS • Predominantly sampled for physical (temperature/dissolved oxygen), nutrients, major ions, algal biomass (chl a) and bacteria • More recently, additional sampling for microcystin (algal toxin)

Trophic Status • Classified as eutrophic, water can be green through most of the summer • Typical of central Alberta lakes – surrounding soils rich in phosphorus • Mitchell and Prepas (1990) – estimated external P sources – 16% forested/bush – 30% agriculture/cleared – 14% residential/cottage – 2% sewage – 38% dustfall/precipitation Trophic Status

Average of Average of Total Average of Secchi Name Chlorophyll-a (ug/L) Phosphorus (ug/L) Depth (m) 4.6 20.6 4.7 8.7 45.6 2.4 Main Basin 11.2 65.2 2.1 Battle Lake 11.4 39.1 3.8 Pigeon Lake 15.8 31.8 2.2 18.7 72.2 2.8 49.9 280.9 1.3 47.4 227.1 n/a Trophic Status

70.0 Chl a 0.0 TP Secchi 1.0 60.0 2.0

50.0 3.0

4.0 40.0 5.0

30.0 (m) Depth

6.0 Chl-a and TP (ug/L) TP and Chl-a 20.0 7.0

8.0 10.0 9.0

0.0 10.0

1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2002 2003 2005 2006 2007 2008 2009 2010 Water Quality Summary • Water quality of Pigeon Lake comparable to other lakes in Alberta – slightly eutrophic with high major ion concentration: reflection of natural geology • Very little historical change in water quality of Pigeon Lake – Slight increase in algal biomass – Slight increase in major ion concentration – Above could reflect lack of flushing in the lake • Metals have not exceeded applicable guidelines • Few pesticides detected in low concentrations typical of other lakes in the area