Presentation on theme: "Dodge County Waters : Programs and Trends. What is the quality of the ground water and surface water in Dodge County ? Is the quality improving or worsening?"— Presentation transcript:
What is the quality of the ground water and surface water in Dodge County ? Is the quality improving or worsening? Water monitoring efforts over the last 12 years have provided some answers and raised additional questions, as well. Changing environmental conditions, and high public interest, provide the impetus to continue to gather and learn from accurate water quality data. All activities & projects contained in this presentation are in support of directives set forth in the Dodge County Comprehensive Water Management Plan.
The Dodge County Comprehensive Water Management Plan clearly states that groundwater protection takes priority over surface water protection. In Dodge County, Ground Water is #1 !!!! Our ground water management plan revolves around:
DODGE COUNTY WATER ISSUES GROUND WATER Nitrate Bacteria Lead Arsenic Pesticides SURFACE WATER Nitrate Sediment Bacteria Stream Flow Phosphorous
To better understand ground water, it’s important to visualize the rock layers, most of which serve as drinking water aquifers, which exist under Dodge County, moving from deepest to shallowest.
Let’s cut through the rock layers and expose them from a side view.
EllingtonConcordMilton WESTEAST 900 1000 1100 1200 900 1000 1100 1200 1300 SOIL, SAND & GRAVEL GALENA LIMESTONE DECORAH SHALE ST. PETER SANDSTONE PRAIRIE DU CHIEN DOLOMITE/SANDSTONE 0 1 2 3 4 5 6 Miles Generalized Geographic Formations Underlying Ellington, Concord and Milton Townships Subsurface Geologic Cross-Section Elevation Above Sea Level (ft) In general, the thicker soils in the western portion of the county provide more protection from surface contaminants reaching the rock layers.
Generalized Geographic Formations Underlying Ellington, Concord and Milton Townships Subsurface Geologic Cross-Section 900 1000 1100 1200 900 1000 1100 1200 1300 SOIL, SAND & GRAVEL GALENA LIMESTONE DECORAH SHALE ST. PETER SANDSTONE PRAIRIE DU CHIEN DOLOMITE/SANDSTONE 0 1 2 3 4 5 6 Miles Elevation Above Sea Level (ft) MiltonConcordEllington WESTEAST ~60% of all wells ~15% of all wells ~ 10% of all wells Shallow Well, < 50 Ft. to Bedrock Deep river valleys in the eastern portion of the county can erode the protective shale layer, exposing the layers below to contamination.
900 1000 1100 1200 1300 900 1000 1100 1200 1300 ClaremontWasiojaMantorville EAST SOIL, SAND & GRAVEL GALENA LIMESTONE DECORAH SHALE ST. PETER SANDSTONE PRAIRIE DU CHIEN DOLOMITE/SANDSTONE 0 1 2 3 4 5 6 Miles Subsurface Geologic Cross-Section Generalized Geographic Formations Underlying Ellington, Concord and Milton Townships WEST Elevation Above Sea Level (ft)
GALENA LIMESTONE DECORAH SHALE ST. PETER SANDSTONE PDC SOIL, SAND & GRAVEL Subsurface Geologic Cross-Section Elevation Above Sea Level (ft) Generalized Geographic Formations Underlying Ellington, Concord and Milton Townships 900 1000 1100 1200 1300 900 1000 1100 1200 1300 WEST RipleyAshlandCanisteo EAST
GALENA LIMESTONE DECORAH SHALE ST. PETER SANDSTONE PDC Elevation Above Sea Level (ft) WEST WestfieldHayfieldVernon EAST CEDAR VALLEY-MAQUOKETA LIMESTONE 900 1000 1100 1200 1300 900 1000 1100 1200 1300 SOIL, SAND & GRAVEL Generalized Geographic Formations Underlying Ellington, Concord and Milton Townships Subsurface Geologic Cross-Section 0 1 2 3 4 5 6 Miles
Nitrogen Fertilizer Applied Run Off to Surface Water Nitrate Utilized by Plant in Root Zone Nitrate Moves into Field Tile, Then to Surface Water Nitrate Attaches to Water, Then Moves to Ground Water Nitrate’s Pathway to Surface and Ground Water
High nitrate wells occur most frequently in the Highly Sensitive Groundwater Area, where depth-to-bedrock is less than 50 ft, or where underground sand lenses exist.
AQUIFER - NITRATE SUMMARY FOR WELLS TESTED 1996 - 2011 NITRATE LEVEL AQUIFER0-1 mg/l1-10 mg/l10+ mg/l GALENA LIMESTONE 75 %17 %8 % ST. PETER 89 %11 %0 % PRAIRIE du CHIEN JORDAN 100 %0 % Nitrate levels > 1 mg/l in the St. Peter Sandstone are a reason for concern.
Areas of Dodge County where the St. Peter Sandstone is shallow and vulnerable to surface contamination.
Dodge County Volunteer Nitrate Monitoring Network A grant-funded network operating across SE MN since 2007. Approximately 100 private well owners participate in Dodge County, sampling their wells every 6 months. The Dodge County network is sub-divided into one baseline, and three targeted, groups. The targeted groups are: 1)Wells monitoring areas near known high-nitrate wells. 2) Wells monitoring areas near existing sinkholes. 3) Wells monitoring the region along the Decorah Edge. Ground Water Projects:
St. Peter Sandstone Glenwood Shale Platteville Limestone Decorah Shale Galena Limestone Ground water with high nitrate conc. Ground waters with lower nitrate conc. Plant Uptake Aquifers are Recharged Decorah Edge Diagram Water Well Nitrates may enter well water Wells near the Decorah Edge can sometimes be affected by nitrate as it wicks around the shale and is drawn back toward the well.
Volunteer Nitrate Monitoring Network Results Nitrate Level (mg/l) MN Dept. of Health Drinking Water Limit = 10 mg/l 0 – 1 mg/l is considered back- ground level The recent upward trend in nitrate level may be due, in part, to recent near-drought conditions, which tend to concentrate nitrate in the drinking water aquifers.
Future Ground Water Efforts: Continue to locate and map new wells and those with known depth. Make inexpensive well test kits available for untested wells at risk of high nitrate levels. Maintain recent groundwater information on the Dodge County website. Continue to develop nitrate trends through the Volunteer Nitrate Monitoring Network.
Trendline Sample of the Index of Biotic Integrity (IBI) results generated by examining and sorting the macroinvertebrates (bugs) gathered from each stream site. Upward trend lines indicate an improving stream environment for living organisms.
Cedar River Grade: B- Sub-Watershed Report Cards* * Based on transparency tube readings, insect populations, and other factors. Factors include sub-watershed size, land use, historical data, and soil characteristics.
CONTINUOUS STREAM MONITORING STATION Located on the South Branch Middle Fork Zumbro near Olmsted County, this station continuously monitors: Air Temperature Rainfall Water Temperature Water Depth Turbidity
Sampling sensors are an essential part of the monitoring station.
Ongoing & Future Surface Water Programs & Projects: BeforeAfter Dodge County 50-Foot Stream Buffer Program Buffers provide a deterrent to the movement of soil and nutrients into the stream.
Increasing Row Crop Production Increases the Importance of Adequate Stream Buffers to Protect Water Quality
In Dodge County, 276 failing or inadequate septic systems have been repaired or replaced in the last 5 years. Both the septic and feedlot programs provide pollution prevention benefits to both surface water and ground water. 13 problematic feedlots have been fixed in the last 3 years.
Date Nitrate Level (mg/l) Field tile drainage is diverted through the woodchips, where a high percentage of nitrate is removed.
Using Saturated Buffers for Nitrate Removal Field tile water runs through a perforated tile parallel to the buffered ditch or stream, allowing limited drainage through the buffer, which reduces nitrate levels.
Edge-of-Field Monitoring Stations Water samples are gathered and analyzed, providing accurate information to producers on nutrients that leave their fields during snow-melt and runoff events. Discovery Farms SiteMN Dept. of Ag. Grant Site
SLOW THE FLOW ! Reducing flood potential and sediment transfer by reducing the quantity and speed at which rainfall reaches the stream. 100 years ago, 10% of rainfall ran off to rivers and streams due to extensive prairies, woodlands, wetlands. We’ve now lost 95% of prairies, 90% of wetlands. Prior to 1942 – one major flood – since then, 11 major floods. Development of paved surfaces, more lawns, ag. drainage, etc. – all contributed to 41% flow increase between 1910 – 1980. Stream bank erosion may account for 30+% of stream sediment.
Mantorville – South Branch Middle Fork Zumbro - September 2010
Mantorville - South Branch Middle Fork Zumbro - June 2004
Mantorville - South Branch Middle Fork Zumbro - June 2001
2007 photo – Bridge near Byron Sportsmen’s Club
2011 photo – Bridge near Byron Sportsmen’s Club
Urban:Rural: Rain Gardens Stormwater Holding Ponds Rain Barrels Pervious Paving Lawn Management Wetland Restoration Conservation Drainage Water & Soil Retention Structures Perennial Vegetation What Can We Do ?
Future Surface Water Efforts Continue to promote the Stream Transparency Monitoring & Stream Macroinvertebrate Programs. Work with partners and cooperating agencies to develop new projects and programs which serve to reduce nutrients, sediment, and stream flow. Expand the number of instrument-equipped sampling stations on Dodge County streams. Maintain recent surface water information on the Dodge County website.