Missouris Lakes and Reservoirs Tony Thorpe Dan Obrecht

Missouri’s Lakes and Reservoirs Tony Thorpe Dan Obrecht Jack Jones Lakes of Missouri Volunteer Program The University of Missouri-Columbia The Missouri Department of Natural Resources Region V 11, US Environmental Protection Agency, through the Missouri Department of Natural Resources, has provided partial funding for this project under Section 319 of the Clean Water Act

405 Classified Lakes/Reservoirs • ~108 are Drinking Water Supply (LC 1) • 14 are Major Reservoirs (LC 2) Most are man-made reservoirs, with about 15 - 20 oxbow lakes.

Of the 405 Classified Waterbodies, we have at least 4 years worth of data on 134 What follows is a summary of the physical features of those 134 waterbodies “A central paradigm of modern limnology is that external nutrient loading, modified by morphology and hydrology, determines the trophic state of a lake. ” Jones et al. 2005

Lake Morphology • Surface Area • Depth • Volume Lake Hydrology • Watershed Area • Residence Time External Loading • Land Use

Surface Area Ranges from 6 to 53, 814 acres in size, with a median of 103 acres.

Break down by size 30% of classified lakes are 20 acres or less in size. 10% are greater than 300 acres in size.

Average Depth Ranges from 3. 7 feet to 62 feet, with a median of 11. 6 feet.

Lake Volume Ranges from 48 to 2, 700, 000 acre-feet, with a median of 1, 675 acre-feet. 1 foot 1 acre-foot = 325, 851 gallons

Lake Hydrology

Watershed Area Ranges from 83 to > 4, 000 acres, with a median of 2, 516 acres.

Residence Time Ranges from 2. 6 days to 9 years, with a median of 10. 5 months.

External Loading

Land Cover within watersheds Forest = 0 – 95% Grass = 0 – 78% Crop = 0 – 74% Urban = 0 – 96% Using the 134 classified lakes for which we have >= 4 years worth of data

Land Cover and Water Quality: Row Crop Data points based on summertime averages near the dam

Land Cover and Water Quality: Forest Data points based on summertime averages near the dam

Trophic Classification TP TN CHL a Oligo 10 11 15 Meso 36 22 23 Eutro 81 92 92 Hyper 7 9 4

Distributions based on long-term averages

# of waterbodies IX – 20 ug/L XI – 8 ug/L (EPA recommendations as of July 2002) Phosphorus (micrograms per liter)

# of waterbodies IX – 360 ug/L XI – 460 ug/L (EPA recommendations as of July 2002) Nitrogen (micrograms per liter)

# of waterbodies IX – 4. 9 ug/L XI – 2. 8 ug/L (EPA recommendations as of July 2002) Chlorophyll (micrograms per liter)

Break down by size “Small” Reservoirs: less than 2000 acres “Large” Reservoirs: more than 2000 acres

“Large” Reservoirs 2004 LMVP Data

“Small” Reservoirs Inset is to scale 2004 LMVP Data

Types of Variability • Temporal • Spatial

Temporal Variability

Phosphorus (ug/L) Little Dixie Lake – Seasonal Patterns 2004 LMVP Data

Phosphorus (ug/L) Little Dixie Lake – Seasonal Patterns

Range = 37 – 95 ug/L

Spatial Variability

Phosphorus Concentrations: Lake of the Ozarks 2002 LMVP Data Variability within a lake

Phosphorus Concentrations: Table Rock Lake 2002 LMVP Data Variability within a lake

Phosphorus Concentrations: Longview Lake 25 930 acres Approximately 1 mile between the two sites. 27 Variability within a lake