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2015 Valley Branch Watershed District Watershed Management Plan Downs Lake Watershed Management Plan Barr Engineering Company Page 5.14-i P:\Mpls\23 MN\82\2382174\WorkFiles\2015 VBWD Plan\Final\Section 5.14- Downs Lake.doc

5.14 Downs Lake Watershed Management Plan ....................................................... 5.14-1 5.14.1 General Information ............................................................................. 5.14-1 5.14.2 Water Quality Management Plan .......................................................... 5.14-2

5.14.2.1 5.14.2.1 Water Chemistry Data .............................................. 5.14-4 5.14.2.2 Biological Data ...................................................................... 5.14-5

5.14.3 Water Quantity Management Plan ........................................................ 5.14-5 5.14.3.1 Drainage Patterns ................................................................... 5.14-6 5.14.3.2 Water Levels and Low Structures ........................................... 5.14-6 5.14.3.3 Water Quantity Management History ..................................... 5.14-7 5.14.3.4 Downs Lake Flood Duration Reduction Project ...................... 5.14-9 5.14.3.5 Other Water Quantity Issues ................................................. 5.14-11

5.14.4 Groundwater ....................................................................................... 5.14-12 5.14.5 References ........................................................................................... 5.14-12

List of Tables

Table 5.14-1 Summary of Downs Lake summer average water quality ................................. 5.14-4

Table 5.14-2 Homes and Structures Affected by High Water Levels on Downs Lake, Eden Park Pond, and Durand’s Pond ............................................................................. 5.14-8

Table 5.14-3 Operation Plan – Downs Lake Flood Duration Reduction Project ................... 5.14-10

List of Figures

Figure 5.14-1 Downs Lake Watershed – Subwatersheds and Flow Routing ................ 5.14-14

Figure 5.14-2 Downs Lake Watershed – Current (2010) and Future (2030) Land Use ........... ............................................................................................................ 5.14-15

Figure 5.14-3 Downs Lake Water Quality Data Summary .......................................... 5.14-16

Figure 5.14-4 Downs Lake Outlet Routing ................................................................ 5.14-17

Figure 5.14-5 Downs Lake Outlet Floodplain ............................................................ 5.14-18

Figure 5.14-6 Downs Lake Water Level Data ............................................................ 5.14-19

Figure 5.14-7 Downs Lake Flood Duration Reduction Project ................................... 5.14-20

Figure 5.14-8 Downs Lake Golf Course Pond Drawdown .......................................... 5.14-21

Figure 5.14-9 Downs Lake 21st Street Drawdown Structure ....................................... 5.14-22

Figure 5.14-10 Downs Lake Legion Lane Drawdown Structure ................................... 5.14-23

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List of Appendices

Appendix A-5.14 Additional Macrophyte Information

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5.14 Downs Lake Watershed Management Plan

5.14.1 General Information

Downs Lake is on the eastern border of the City of Lake Elmo, west of Manning Trail North and north of 20th Street North. The lake has a surface area of 34 acres and a large tributary watershed of 2,339 acres. Figure 5.14-1 shows the Downs Lake watershed.

Drainage from the commercial area north of T.H. 5 in the City of Lake Elmo and the Lake Elmo Airport in Baytown Township flows to Downs Lake. The Eden Park development surrounds the lake on the south and west sides, and the Downs Lake Estates developments are located east of the lake. Approximately 20% of the tributary area is residentially developed, 3% is Tartan Park, and the remainder is a mix of cultivated and pasture agricultural land uses. Estimated future (2030) land assumes the conversion of much of the agriculture land use to residential land use, including single family residential land use around T.H. 5 and large-lot residential land use south of 30 th Street North. Figure 5.14-2 presents the existing (2010) and estimated future (2030) land use of the Downs Lake watershed.

There is no public access to Downs Lake. Local residents report that Downs Lake is primarily used for aesthetic viewing. A large portion of the shoreline is rocky or contains natural vegetation. Some residents use the lake for paddle boating, sailing (small sailboats), and canoeing. The lake is not used for swimming.

Part of the Downs Lake watershed around the Lake Elmo Airport lies within the

Downs Lake Watershed Information

Tributary Area (acres) 2,339

MDNR-Designated Basins within Watershed

82-0484W, 82-0461W, 82-0463W (Eden Park Pond), 82-0110W (Downs Lake)

Downstream Watershed

Downs Lake Information

MDNR Designation 82-0110W

Surface Area (acres) 34.2 at El. 887.4

Approximate Mean Depth (feet) 5

Approximate Maximum Depth (feet) 7

Approximate Volume Below Discharge Elevation (acre-feet)

Not determined

Discharge Elevation 891.5 (can be drawn down to 887.6)

Outlet Type Overland

MDNR Ordinary High Water Level (OHW)

1

889.1

100-Year Flood Level 893.0

VBWD “Allowable Fill” (cubic yards/lineal foot of shoreline) (See Section 4.7.)

1.4

VBWD Water Quality Priority Category High 1 Elevations in NGVD29 datum


Baytown/West Lakeland Township Groundwater Contamination Site. Section 4.2 – Groundwater Management provides more information about the Baytown/West Lakeland Township Groundwater Contamination Site.

5.14.2 Water Quality Management Plan

Downs Lake is classified as a shallow lake by the Minnesota Pollution Control Agency (MPCA). Downs Lake is currently listed as impaired for aquatic recreation by the MPCA due to nutrients, eutrophication, and biological indicators, and is included in the MPCA’s 303(d) impaired waters list because of excessive nutrients.

The VBWD classified Downs Lake as a High Priority waterbody according to its waterbody classification system (see Section 4.1 – Water Quality), due to the lakes inclusion in the MPCA’s impaired waters list (see Table 4.1-5).

Historically, Downs Lake has had poor water quality. The VBWD previously classified Downs Lake as a Level III water body in the 1995 VBWD Water Management Plan and a low priority waterbody in its 2005 Plan; such lakes generally supported fishing and provided opportunities for aesthetic viewing, and observing wildlife.

The VBWD has a non-degradation water quality policy which sets “action triggers” for all of its major waterbodies. Section 4.1 – Water Quality discusses the action triggers in more detail. Action triggers for VBWD lakes consider the following water quality parameters (summer average) relative to MPCA water quality standards and prior water quality data (i.e., trend analysis):

Secchi disc depth

Total phosphorus

Chlorophyll a

Specific water quality implementation tasks for Downs Lake include the following:

1. The VBWD will cooperate with other entities to monitor the water quality of Downs Lake and perform the actions discussed in Section 4.1 – Water Quality for High Priority water bodies. The VBWD may conduct more intense monitoring of the lake as needed based on actions recommended in Table 4.1-6.

The VBWD will evaluate the average summertime water quality (total phosphorus, chlorophyll a, and Secchi disc transparency) and compare it to applicable water quality standards (Table 4.1-4) and applicable action triggers (described in Section 4.1.7.5). Based on Table 4.1-6, the VBWD may perform Survey Level plus Supplemental Water Quality Monitoring, as necessary.

2015 Valley Branch Watershed District Watershed Management Plan Downs Lake Watershed Management Plan Barr Engineering Company .14-3 P:\Mpls\23 MN\82\2382174\WorkFiles\2015 VBWD Plan\Final\Section 5.14- Downs Lake.doc

2. The VBWD will consider implementing the following actions to improve water quality in Downs Lake:

a. More intense monitoring to better estimate how much phosphorus is entering the lake, and ultimately, determine the feasibility and cost-effectiveness of improvement options identified in this Plan or subsequent studies.

b. Evaluating the feasibility of enhanced treatment and small scale stormwater BMPs within the watershed tributary to Downs Lake. The VBWD’s BMP cost-share program may provide opportunities for private landowners to implement water quality improvements. Collectively, many small residential BMPs may have a significant impact on the cumulative phosphorus loading to Downs Lake.

c. If necessary, the VBWD will cooperate with the MDNR and others to reduce internal loading in Downs Lake. This may include an in-lake aluminum sulfate (alum) treatment of Downs Lake. In-lake alum provides a long-term control of the phosphorus release of lake sediments (see Section 4.1 – Water Quality). An in-lake treatment could be effective for up to ten years, depending upon how well the watershed nutrient sources have been reduced. When alum is applied to shallow lakes, the improved water clarity usually results in increased (and often undesired) aquatic plant growth. This can be exacerbated by the presence of aquatic invasive plant species. The VBWD will need to consider improved water clarity versus increased aquatic plant growth before moving forward with alum application projects on these lakes.

d. Management of macrophytes (aquatic plants) of the lake. Treatment of areas containing dense, monospecific growths of Eurasian watermilfoil with an aquatic herbicide (2,4-D, Triclopyr, or low concentrations of Aquathol® K) is recommended to protect Downs Lake’s native plant community. The VBWD will cooperate with the City of Lake Elmo or other entities in support of macrophyte management efforts. VBWD efforts may include

point-intercept surveys of aquatic vegetation

preparation of lake vegetation management plans (LVMP)

completion of Invasive Aquatic Plant Management (IAPM) Permit applications

design of herbicide treatment programs

participation in meetings with MDNR staff

other technical analysis


3. The VBWD will cooperate with the MPCA to participate in any required total maximum daily load (TMDL) study and TMDL implementation plan for Downs Lake. This may include collaboration with Municipal Separate Storm Sewer System (MS4) permit holders (e.g., City of Lake Elmo, Washington County, Minnesota Airports Commission, etc) to meet waste load allocations determined by the TMDL study.

4. The VBWD will consider collecting sediment core samples from Downs Lake to assess the potential for internal phosphorus loading from sediments.

5. The VBWD will continue to implement its Rules and Regulations (2013, as amended) in the Downs Lake watershed. The VBWD Rules address water quality performance standards for development and redevelopment projects, as well as required vegetated buffers around VBWD lakes, streams, and wetlands. The VBWD Rules and Regulations are included in this Plan as Appendix A-4.5.

5.14.2.1 Water Chemistry Data

Water quality sampling has been conducted on Down’s Lake since 1986. The VBWD conducted water quality sampling in 1999, 2005, 2006, 2007, 2009, 2012 and 2013. Water quality samples are typically analyzed for total phosphorus and chlorophyll a, while Secchi disc transparency is measured in the field at the time of sampling (see Appendix A-4.1 – Water Quality Background Information).

The most recent 10-year average summer water quality data is presented relative to applicable MPCA and VBWD water quality standards in Table 5.14-1 and illustrated in Figure 5.14-3.

Table 5.14-1 Summary of Downs Lake summer average water quality

Parameter Units

10-year

Average

(2004-2013)

Trend in

Average

MPCA

Standard

Total Phosphorus ug/L 205 None 60

Chlorophyll a ug/L 108 None 20

Secchi Disc Depth m 0.3 None 1.0

The 10-year averages of summer average total phosphorus, chlorophyll a, and Secchi disc transparency all exceed (i.e., are worse than) the applicable water quality standards (see Table 5.14-1). Summer average total phosphorus, chlorophyll a, and Secchi disc transparency have exceeded the MPCA standard in each year sampled since 1997, with maximum summer averages of total phosphorus (300 ug/L) and chlorophyll a (181 ug/L) occurring in 2012. The most recent 10-years of data identify no statistically significant trends in total phosphorus, chlorophyll a, or Secchi disc transparency.


5.14.2.2 Biological Data

The Down’s Lake fishery is not managed by the MDNR. There are no fish stocking or fish survey programs, and no fish consumption advisories have been posted for Down’s Lake. Down’s Lake does not have a fisheries use classification.

Local residents report the lake contains panfish, minnows and bullheads. Walleye fry were stocked in the lake during 1986 in an effort by a local resident to improve the lake’s fishery. The resident periodically operated an aerator infrequently to keep the fish alive. The VBWD does not know whether the aerator is still operated, and whether walleye are still present in the lake.

The MDNR Lakefinder website includes the most current data on the lake and is available at: http://www.dnr.state.mn.us/lakefind/lake.html?id=82011000

Phytoplankton, (non-rooted, floating plants – algae), and zooplankton (microscopic aquatic animals) surveys have not been conducted at Downs Lake.

5.14.2.2.1 Macrophyte (large aquatic plant),

Macrophyte surveys were conducted in 2009 and 2012 in Down’s Lake. Appendix B-5.14 includes maps corresponding past macrophyte surveys of Down’s Lake. The VBWD collects this macrophyte data to identify the conditions of plant growth throughout the lake. Macrophytes are the primary producers in the aquatic food chain, converting the basic chemical nutrients in water and soil into plant matter through photosynthesis, which becomes food for all other aquatic life. Macrophytes can negatively impact the recreational use of a waterbody and are critical to the ecosystem as fish and wildlife habitat.

Down’s Lake has a stable macrophyte community which consists mostly of emergent plants along the shoreline and limited floating and submerged plant communities. All the species observed in Down’s Lake during these surveys are native to Minnesota.

5.14.3 Water Quantity Management Plan

1. The VBWD will continue to maintain and operate the Downs Lake Flood Duration Reduction Project structures. The operating plan for the project is discussed in Section 5.14.3.4of this Plan.

2. The VBWD will continue to monitor Downs Lake water levels at approximately monthly intervals and supply the information to the MDNR. The VBWD will include the water level measurements in its annual report, which is posted to the VBWD’s website.

3. The VBWD will cooperate with the City of Lake Elmo and project proposers to identify and evaluate the feasibility of options to mitigate or prevent negative impacts to water levels due to new development within the Downs Lake watershed.

http://www.dnr.state.mn.us/lakefind/lake.html?id=82011000


5.14.3.1 Drainage Patterns

Downs Lake receives the majority of its inflow from an intermittent stream, which begins approximately one mile north of the lake at the Union Pacific Railroad and enters the northeast bay of Downs Lake. The small size of Downs Lake (relative to its drainage area), coupled with the fact that Downs Lake has a high overflow point, results in a high potential for flooding. When large quantities of water flow into the lake – as a result of an unusually heavy and long-lasting rainstorm or a sudden spring thaw of heavy snow cover – the lake fills to a point where it overflows. Prior to the lake level reaching the overflow, however, roadways are inundated, and a home and subsurface sewage treatment systems (SSTS) are flooded.

The Downs Lake overflow path is complicated, as shown on Figure 5.14-4. The waterbodies in the Downs Lake area, and the 100-year floodplain for Downs Lake and the associated waterbodies are shown in greater detail on Figure 5.14-5.

The elevation at which Downs Lake flows out of Downs Lake watershed (i.e., not to an adjacent landlocked basin) is Elevation 891.5. Below this elevation, Downs Lake first begins spilling water west into Eden Park Pond at Elevation 891.1. From the east, Durand’s Pond spills into Eden Park Pond at Elevation 884.3. Downs Lake spills to the south to a small wetland between the lake and 20 th Street at Elevation 891.5. This small wetland overflows to the south into a pond located in the northeast corner of 3M’s Tartan Park golf course (Golf Course Pond). At higher water levels, Golf Course Pond, the small wetland, Downs Lake, Eden Park Pond, and Durand’s Pond behave as one waterbody and would have to fill to Elevation 891.5, before they would overflow a high point near Manning Trail North and 20th Street North. From there the water flows southward through a ditch system, eventually arriving at Horseshoe Lake (see Section 5.15 for the Horseshoe Lake Watershed Management Plan).

5.14.3.2 Water Levels and Low Structures

Downs Lake has a maximum depth of approximately seven feet and an average depth of about five feet, under “normal” water level conditions. About half of the lake is less than four feet deep, and the two north bays average three feet in depth. The lake has widely fluctuating water levels. The MDNR reports that annual water levels fluctuated from four feet above normal to 1.5 feet below normal during the years preceding its 1976 survey of the lake. The MDNR and local residents report Downs Lake was at a very low level for an extended period of time following the 1987 through 1988 drought period. Although large water level fluctuations between Elevation 884 and Elevation 891 are common, overflow is infrequent. The VBWD began measuring the water level of Downs Lake in 1982. Figure 5.14-6 shows the historical water levels. The highest measured water level was 890.9 in October of 1986. The lake was very close to overflowing to Eden Park Pond during the 1989 spring snowmelt, but the peak lake elevation was not measured. Water levels approached the overflow elevation again in the Spring of 2001, and in the Summers of 2013 and 2014.

Some flooding events occurred prior to the formation of the VBWD. Local residents report that during the 1965 flood, water from Downs Lake flooded 20th Street North to a depth of three feet.


This corresponds to an approximate lake level of Elevation 892 (see Figure 5.14-6). Residents report that 20th Street North flooded again in the spring of 1966.

The large drainage area to Downs Lake leads to the potential for sizeable runoff volume, well in excess of the lake’s storage capacity. The infrequent overflows from Downs Lake indicate a high infiltration capacity in the watershed and/or high seepage outflow from the lake. The VBWD and City of Lake Elmo anticipate a significant amount of future development within the Downs Lake watershed. As development in the Downs Lake watershed continues, discharges from Downs Lake to Horseshoe Lake may occur.

The VBWD has assigned a 100-year flood level for Downs Lake of Elevation 893. In 2003, the VBWD submitted information to Washington County as it updated the Federal Emergency Management Agency (FEMA) floodplain maps. The older maps included the 100-year flood level of Downs Lake (Elevation 893), but not the other adjacent lowlands. Because the various lowlands are connected and act as one large basin at high water levels, the information VBWD submitted to Washington County assigned the same flood level to the entire area. The Washington County Flood Insurance Rate Maps (FIRMs) effective as of 2010 include the 100-year flood level for all of the basins at Elevation 893.

One home on Legion Avenue North, adjacent to Eden Park Pond, is within the 100-year floodplain of Downs Lake/Eden Park Pond/Durand’s Pond. The basement of the lowest home is estimated to be between Elevation 886.0 and 886.5; the lowest opening is at Elevation 889.9. An additional home was previously within the Downs Lake/Eden Park Pond floodplain, but was removed by a 2013 Letter of Map Amendment (LOMA #13-05-7450A).. Figure 5.14-5shows the locations of the lowest homes in the area and Table 5.14-2 lists the homes and associated structures.

5.14.3.3 Water Quantity Management History

In implementing the 1995 Water Management Plan, the VBWD included Downs Lake in a flood relief study for multiple landlocked basins. The study determined that a project creating emergency overflows for Sunnybrook Lake, Goetschel Pond, Cloverdale Lake, and Downs Lake would be a feasible solution to flooding problems at several of these landlocked basins. A study specific to Downs Lake, Downs Lake Study: An Evaluation of Flood Control Options , was completed in January 2000. Several memoranda that evaluated specific details regarding Downs Lake flood relief, including upstream storage, followed the January 2000 report.

Based on the findings of the larger landlocked basin flood relief study and the specific Downs Lake study, the VBWD Board of Managers attempted to amend the 1995 Water Management Plan to allow for a more detailed study of the larger flood relief project and the design and eventual construction of the project. However, the proposal met strong opposition from Washington County, the City of Lake Elmo, some residents, the MDNR, the Washington Soil and Water Conservation District, and the MPCA. In early 2001, the VBWD Managers withdrew the proposed draft amendment to their 1995 Plan.


Table 5.14-2 Homes and Structures Affected by High Water Levels on Downs Lake, Eden

Park Pond, and Durand’s Pond

Figure 5.14-5 Map

Number Address Legal

Description Structure

Location of Measured Elevation

Estimated Minimum Structure Elevation

Estimated Septic

System Elevation

1 2257 Legion Ave. N Lot 2, Block 4, Eden Park

House Door Sill 886.5 889.0

21 2229 Legion Ave. N Lot 1, Block 4,

Eden Park House

Shed

Window Sill

Door Sill

890.39

894.69

900

3 11950 21st

St. N. Lot 1, Block 1, Eden Park 2nd

House Garage Slab 893.45 Not determined

4 11920 21st


House

Shed

Gazebo

Window Sill

Door Sill

Concrete Slab

893.89

892.79

891.09

Not determined

5 2390 Legion Lane N.

Lot 6, Block 4, Eden Park

House Walkout Sill 894.4 897.4

6 2204 Legion Lane Circle North


House

Stucco Shed

Garage Slab

Door Sill

894.52

886.25

Not determined

7 11909 21st


House Walkout Sill 894.94 Not determined

8 2329 Legion Ave. N. Lot 4, Block 4, Eden Park

House Walkout Sill 895.0 Not determined


House Window Sill 895.94 893.0

10 2040 Manning Trail North

-- House

CMP Shed

Concrete Shed

Window Sill

Door Sill

Door Sill

<891.03

893.55

890.49

Not determined

11 2194 Legion Lane Circle North


House

Equip. Shed

Walkout Door

Door Sill

899.50

892.60

Not determined

12 11860 21st

St. N. Lots 3 & 4, Block 1, Eden Park

House

Tennis C’rt

Equip. Shed

Garage Slab

Conc. Slab

Door Sill

897.8

894.12

893.47

Not determined

13 11933 21st


House Window Sill <899.03 Not determined


House Garage Slab 897.53 891.1

1 Removed from floodplain per Letter of Map Amendment #13-05-7450A

Note: Elevations for Durand’s Pond based on 1988 VBWD survey.

Because the VBWD 1995 Water Management Plan also included a stand-alone project for flood relief at Downs Lake, the VBWD Managers focused their attention on Downs Lake. After evaluating options, the VBWD Managers chose a project that did not eliminate flooding of the low home or roads. Although the 100-year flood elevation did not change as a result of the project, the following benefits resulted from the project:

Flood levels recede at a much faster rate than under pre-project conditions


Flooding of streets, yards and trees is reduced

Downstream flood levels are not increased because the outflow from the Downs Lake will be limited

Although the primary purpose of the project was to draw water down after flooding, the project has some ability to draw water down in anticipation of a flood event.

When the plans for the project were near completion, the VBWD Managers presented the project to the Lake Elmo City Council in the fall of 2001. The Council passed a resolution supporting the project.

The VBWD Managers then invited residents of the Downs Lake neighborhood to a meeting to discuss the project. The residents had many suggestions for alternatives in the project . Those alternatives were evaluated and presented to the residents in another public meeting in early 2002. After the second neighborhood meeting, the VBWD Managers ordered the completion of plans and specifications for the project. The $132,500 project, referred to as the Downs Lake Flood Duration Reduction Project, was constructed over the winter of 2002-2003.

The project is not a full-solution to the flood problems in the neighborhood. As development in the Downs Lake watershed continues, more impervious area will be created, which may cause volume of storm water runoff to increase. This increase may be offset to a degree by the VBWD regulations which require some level of volume reduction (see Appendix A-4.5). Increased runoff volumes from development may cause the normal water level of Downs Lake to rise and increase the chances of flooding. Section 4.5 provides more information regarding VBWD rules addressing stormwater volume controls and infiltration. As new development is proposed within the Downs Lake watershed, the VBWD will work with the City of Lake Elmo and others to identify and evaluate options to mitigate potential impacts to Downs Lake water levels.

In 2014, the VBWD performed XP-SWMM modeling to evaluate a potential diversion of runoff from the Downs Lake watershed towards Sunfish Lake (Barr, 2014). The modeling indicated that the estimated increase to the 100-year flood level of Sunfish Lake would be significant (see Section 5.25). Based on these results, the VBWD Managers did not support the diversion

5.14.3.4 Downs Lake Flood Duration Reduction Project

Figure 5.14-7shows the layout of the Downs Lake Flood Duration Reduction Project. The project created emergency drawdown devices at three overflow locations:

Golf Course Pond Drawdown

A pipe system was constructed within the right-of-ways of 20th Street and Manning Trail. A constructed manhole structure connects the pipe system to the existing culvert under 20 th Street. The manhole structure was equipped with two sluice gates that allow for the possible diversion of water from the Golf Course Pond (see Figure 5.14-8). The pipe system outlets near a pre-existing culvert under Manning Trail. Originally, a vegetated swale was proposed, but to save


trees, avoid purchasing necessary easements, and reduce future maintenance, the pipe was substituted.

21st Street Drawdown

The 21st Street drawdown consists of pipes entering and exiting a manhole structure that is equipped with two sluice gates. The gates can be manually operated to lower the water level of Downs Lake (see Table 5.14-3 of the operation plan for details). Figure 5.14-9shows the 21st Street Drawdown structure.

Table 5.14-3 Operation Plan – Downs Lake Flood Duration Reduction Project

Downs Lake

Water Level

Operation at

Structure 1

Operation at

Structure 2

Horseshoe Lake

Water Level

West Lakeland Storage

Site Water Level

(Upper Cell)

No

n-W

inte

r

Co

nd

itio

ns

890.1 or below

Open Close Both of the following conditions: Horseshoe Lake is below 876.8 and Westland Storage Site is below 867

Above 890.1 Open Open Both of the following conditions: Horseshoe Lake is below 876.8 and West Lakeland Storage Site is below 867

Above 890.1 Close Close Either of the following conditions: Horseshoe Lake is above 876.8 or West Lakeland Storage Site is above 867

Win

ter C

on

dit

ion

s

Above 887.6 Close Close Horseshoe Lake is above 876.8 or West Lakeland Storage Site is above 867

Above 887.6 Open Open All of the following conditions: 1) Water content of snow between February 15 and April 15 is more than 6 inches. 2) Horseshoe Lake is below 876.8 and West Lakeland Storage Site is below 867

Above 889.1 Open Open All of the following conditions: 1) Water content of snow between February 15 and April 15 is more than 4 inches. 2) Horseshoe Lake is below 876.8 and West Lakeland Storage Site is below 867

Above 890.1 See Non-Winter Conditions Notes:

Whenever Structure 2 is open, water levels of Horseshoe and West Lakeland Storage Site will be monitored at l east twice weekly. The weather forecast will also be monitored with the water levels of Horseshoe Lake and West Lakeland Storage Site. If either Horseshoe Lake or West Lakeland Storage Site is above its typical water level and an extreme runoff event is predicted or immediately after an extreme runoff event, both Structure 1 and 2 should be closed at Downs Lake. The golf course pond and Eden Park Pond (and houses, septic systems, and roads) will still flood with the operation of the system. Pumping at Eden Park Pond and Golf Course Pond will be needed to lower the water levels below Elevation 887.6.


Legion Lane Drawdown

A pipe was installed between Downs Lake and Legion Lane. The pipe was fitted with a check valve (located within a manhole structure) that acts like a flap gate. If the water level of Eden Park Pond is ever higher than Downs Lake, water will flow from the pond through the valve into Downs Lake. However, the valve will not allow water to drain from Downs Lake into Eden Park Pond. Water must overflow the preserved existing natural overflow elevation to flow from Downs Lake to Eden Park Pond. Figure 5.14-10shows this structure.

The sluice gates of the Downs Lake Flood Duration Reduction Project require manual operation. As described earlier, no operations are needed for the check valve. The VBWD will operate the system as summarized in Table 5.14-3.

5.14.3.5 Other Water Quantity Issues

In 2013, the National Oceanographic and Atmospheric Administration (NOAA) published Atlas 14, Volume 8 (see Section 4.7.6). Atlas 14 contains updated precipitation data for Minnesota and supersedes data sources used to establish the VBWD and FEMA 100-year flood elevations for Downs Lake. Over the next several years, the VBWD will update its hydrologic-hydraulic modeling of major subwatersheds, including Downs Lake. Updated modeling will incorporate the most recent precipitation data (see Section 4.7.7) which may increase 100-year flood levels relative to the existing levels.

The City of Lake Elmo indicates a high water issue in the Old Village area. In 2004, the City began investigating options for reducing the high water in a channel that runs from Gorman’s restaurant, near the west intersection of Highway 5 and Lake Elmo Avenue (CSAH 17), through the Old Village and into Lions Park. The City considered diverting an area north of Highway 5 and west of CSAH 17 from the Old Village into Sunfish Lake. In the summer of 2004, the VBWD requested from the City additional information on the existing problem and the impacts in the Old Village and on Sunfish Lake caused by a diversion. Such a diversion would reduce the watershed tributary to the Downs Lake and may lower the flood level of Downs Lake.

In 2014, proposed development in this area again prompted consideration of one or more diversions to avoid increased runoff in the Downs Lake watershed. The VBWD assessed the potential impacts and benefits of diverting runoff from multiple proposed residential developments in the Downs Lake watershed out of the watershed. The analysis included hydrologic/hydraulic modeling (using XP-SWMM software) to assess the impact of diverting 127 acres of the Downs Lake watershed to the Goetschel Pond watershed and 245 acres from the Downs Lake watershed to the Sunfish Lake watershed. The potential impacts of these diversions to Geotschel Pond and Sunfish Lake are described in Sections 5.31 and 5.25, respectively. At the same time, the City of Lake Elmo and Washington County evaluated the benefit of the diversions to reduce flooding in Lake Elmo Village. Neither the VBWD nor other entities have quantified the impacts to Downs Lake resulting from any diversions.


A long-term comprehensive Water Management Plan (Wenck, 1999) was prepared for the Lake Elmo Airport in 1999 which includes the proposed construction of new runways, buildings, the relocation of Blackwoods Lane (30th Street North) and wetland filling. In 2014, the Metropolitan Airports Commission (MAC) met with local community representatives to share options for long-term plans for the airport. As of the writing of this Plan, the VBWD has not received and official report. Any improvements at the Lake Elmo Airport must be implemented in accordance with the stormwater management standards and criteria established in the VBWD Rules and Regulations (see Appendix A-4.5) and described in Section 4.5 of this Plan.

5.14.4 Groundwater

Part of the Downs Lake watershed lies within the Baytown/West Lakeland Township Groundwater Contamination Site and Special Well and Boring Construction Area (SWBCA). Following the detection of Volatile organic compounds (VOCs) in the groundwater in 1987 and 1988, the Minnesota Department of Health (MDH) issued a well-drilling advisory (now SWBCA) for portions of West Lakeland Township, Baytown Township, and the City of Bayport. This advisory puts limits on the construction of new wells, and requires additional water testing of new wells. The SWBCA remains in effect as of the writing of this Plan. More information regarding the Baytown West Lakeland Township Groundwater Contamination is within Section 4.2 of this Plan. Current information about this site can be obtained from the Minnesota Department of Health (MDH) and the MPCA.

5.14.5 References

Barr Engineering Company. September 1995. Water Management Plan, Valley Branch Watershed

District.

Barr Engineering Company. January 2000. Downs Lake Study: An Evaluation of Flood Control

Options. Valley Branch Watershed District.

Barr Engineering Company. April 2001. Hydrologic and Phosphorus Budgets for Sunnybrook Lake,

Goetschel Pond, Cloverdale Lake, McDonald Lake, Downs Lake, Horseshoe Lake, and

Fahlstrom Pond. Prepared for Lower St. Croix Valley Watershed District.

Barr Engineering Company. December 2005. Valley Branch Watershed District Watershed

Management Plan.

Barr Engineering Company. January 7, 2015. Flood Levels within the Goetschel Pond and Clear

Lake Watersheds. Memorandum to the VBWD Managers.

Barr Engineering Company. August 29, 2014. Sunfish Lake Flood Level and Diversion Evaluation.

Memorandum to the VBWD Managers.

National Oceanographic and Atmospheric Administration (NOAA). 2013. Atlas 14 Precipitation-Frequency Atlas of the United States – Volume 8.


Wenck. July 1999. Water Management Plan, Lake Elmo Airport. Prepared for Metropolitan Airports Commission.

&-

&-

&-&-

!.

&-&-

!.!.

!.!.

Lake Elmo

EaglePointLake

LakeElmo

SunfishLake

""5

HorseshoeLake

DownsLake

LegionPond

Baytown Township

West Lakeland Township

FL-100 = 899NL = 892.5AF = 413OHW = 896.4

FL-100 = 894NL = 880AF = 118

FL-100 = 893NL = 887.6AF = 640OHW = 889.1

FL-100 = 891NL = 884 (883)AF = 2700OHW = 886

FL-100 = 888.7NL = 883.5AF = 175

Lake ElmoAirport

FL-100 = 893NL = 887.6AF = 640OHW = 889.1

FL-100 = 917

82-311 W

BayLake

BAY-4

DWN-33

FL-100 = 921

EdenParkPond

FL-100 = 901

Stillwater Blvd N

Mann

ing A

ve N

Lake

Elm

o Ave

N

Neal

Ave N

20th St N

30th St N

40th St N

Durand'sPond

DWN-13b

GTL-20GTL-19

BerschensPond

FL-100 = 925.0NL = 915AF = 114

FL-100 = 940NL = 928.9AF = 370

ClearLake

82-99 W

DirksPond

FL-100 = 937.5

FL-100 = 920 FL-100 = 916NL = 913.3

FL-100 = 908NL = 890

GoetschelPond

CloverdaleLake

McDonaldLake

FL-100 = 907.4NL = 899.0AF = 481.0OHW = 900.7

FL-100 = 909.9NL = 905.2AF = 35OHW = 900.7

FL-100 = 891.7NL = 886.0AF = 950OHW = 887.5

FL-100 = 918.4

FL-100 = 891.5NL = 875AF = 650OHW = 885.2

MergensPond

FL-100 = 852.5NL = 832.5AF = 959

FL-100 = 878NL = 875.2AF = 521OHW = 876.8

FL-100 = 917NL = 899AF = 230

FL-100 = 901NL = 894AF = 1150OHW = 896.5

MargaretLake

FL-100 = 900NL = 884AF = 160

GOS-2

Friedrich'sPond

FL-100 = 964

456715

456717

456714

456717

"5

82-106 P

82-109 P

82-74 P

82-107 P

82-9 W

82-10 W

82-110 W

82-461 W

82-11 W

82-111 W

82-313 W

82-108 W

82-462 W

82-417 W

82-484 W

82-392 W

82-312 W

82-482 W

82-391 W

82-414 W

82-419 W

82-311 W82-105 W

82-463 W

82-416 W

82-389 W

82-388 W

82-390 W

82-460 W

82-311 W

82-413 W

EPL-1

ELM-1

CLR-1

MRG-1

JAN-1

SNF-1

CLV-9MCD-1

BAY-25

HRS-1

WLS-19

MRG-23

CLV-1

DWN-5

EPL-8

GTL-1

FRD-5

BAY-1

FRD-1

DWN-6

DWN-19

DWN-1

DWN-16

GTL-5

ELM-4

DWN-17

EPL-4

JAN-2

LEG-2

EPL-5

EPL-6

LEG-1

GTL-6

EPL-7

DWN-14

DWN-8

ELM-3

DWN-9

DWN-10

SNF-7

ELM-5

HRS-4

WLS-24

DWN-4

MCD-33

CLR-6

MRG-21

EPL-2

MCD-34

DWN-18

DWN-7

WLS-20

BAY-4

ROS-6

DWN-27

BAY-30

DWN-13

HRS-17

DWN-15

GTL-7

DWN-11

WLS-26

MRG-26

GTL-12

FRD-2

DWN-20

MRG-28

CLV-6

MRG-14

MCD-25

BAY-11

HRS-5

WLS-28

CLV-7

MRG-12

GTL-15

MCD-32

HRS-8

DWN-24

GTL-10

HRS-2

SNF-6

CLR-5

MCD-21

GTL-9

SNF-2

MCD-28

DWN-3

ELM-6

BTL-40

MRG-19

HRS-7

JAN-3

MRG-18

GTL-4

HRS-13

DWN-34

MCD-26

MCD-4

GTL-8

WLS-21

DWN-23

HRS-6

BTL-39

DWN-22

SNF-8CLV-11

BAY-24

FRD-3

GTL-11

ELM-7

CLV-10

DWN-12

HRS-9 MRG-17

BAY-32

MCD-11

MCD-19

WLS-25

DWN-36

MRG-13

GTL-3

MCD-3

BAY-13

GTL-14

HRS-16

HRS-12

BAY-2

MCD-31

MCD-7

MCD-23

HRS-11

DWN-30

MCD-12

MRG-24

MCD-17

SNF-3

SNF-11

FRD-4

MCD-24

MCD-15

GTL-2

HRS-3

WLS-23

DWN-25

MCD-39

BAY-20

HRS-14

GTL-13MCD-9

BAY-7

MCD-27

BAY-21

DWN-35

MCD-37

MCD-29

SNF-5

HRS-15

DWN-32

SNF-4

BAY-19

DWN-21

BAY-9

MRG-16

LEG-3

ELM-2

DWN-31

CLV-12

MRG-25

HRS-10

MCD-18

SNF-9 MCD-30

MCD-14

WLS-22

MRG-15

BAY-3

BAY-6

MCD-8MCD-5

MRG-27

CLV-8

HRS-19

DWN-29

BAY-39

MCD-22

MRG-22

MCD-13

MRG-20

BAY-31

DWN-2

MCD-20

BAY-11

WLS-27

HRS-18HRS-20

BAY-8

ROS-5

DWN-26

BAY-12

DWN-28

MRG-8

MCD-10

BAY-5

MCD-16

MRG-9

87

13

12

20

14 17

24

11

23

19

18

292526 30

15

22

10

27

3 2

9

16

1

21

Barr Footer: Date: 12/13/2005 4:28:40 PM File: I:\Client\Vbwd\District\Project\WtrshdPlan\Watershed_maps\14-DownsLake_Watershed.mxd User: lkp

Figure 5.14-1DOWNS LAKE WATERSHED

Valley Branch Watershed District

I

LEGEND

Project 1007Catch BasinManhole CoverOpen ChannelPipeMN-DOT Pipe

Overflow Path from Semi-Landlocked Watershed

Subwatershed Contributing RunoffOverflow Path from Landlocked Watershed(Non-Contributing Subwatershed)

Major Watershed DivideSubwatershed Divide

Lakes, Ponds, Wetlands,Approximate Normal Water Surface Level

VBWD Legal Boundary

DWN-1 Subwatershed Designation82-110W DNR Protected Waters Designation

Municipal Boundary

100 Year Flood LevelNL Normal LevelAF Acre Feet of Storage at 100 Year Flood Level

DNR Established Ordinary High Water ElevationOHW

Lakes, Ponds Wetlands, Approximate 100 Year Flood Surface Level

Downs Lake Watershed

Landlocked: Basin does not overflow using VBWD simplified method for calculating its 100-year flood level or using a more detailed analysis, such as the 1% probability flood level.

Semi-Landlocked: Basin does not overflow in the 100-year 24-hour rainfall total or the 100-year 10-day snowmelt event, but does overflow when calulating its 100-year flood level based on the VBWD simplified method or the 1% probablility flood level.

Section Lines

&-

!.

FL-100

Scale in Feet

2000 0 1000 40001000

5

5

5

456715

456717

456714

456717

2,500 0 2,500 5,000Feet

Figure 5.14-2DOWNS LAKE WATERSHED

CURRENT (2010) AND FUTURE (2030) LANDUSE2015-2025 Watershed Management Plan


Barr Footer: ArcGIS 10.2.2, 2014-12-30 16:12 File: I:\Client\VBWD\District\Work_Orders\2015_Watershed_Mgmt_Plan\Maps\Reports\Draft_2015_Plan\Section05\Fig0514_02_DownsLake LandUse.mxd User: mjw

ICurrent (2010) Land Use

FarmsteadSeasonal/VacationSingle Family DetachedManufactured Housing ParkSingle Family AttachedMultifamilyRetail and Other Commercial

OfficeMixed Use ResidentialMixed Use IndustrialMixed Use Commercial and OtherIndustrial and UtilityExtractiveInstitutionalPark, Recreational or Preserve

Golf CourseMajor HighwayRailwayAirportAgriculturalUndevelopedWater

Downs Lake SubwatershedMajor Subwatershed BoundaryVBWD Legal Boundary

Source: Metropolitan Council 2010

5

5

5

456715

456717

456714

456717

1 inch = 2,500 feet

Future (2030) Land UseAgriculturalRural or Large-Lot ResidentialSingle Family ResidentialMultifamily ResidentialCommercial

IndustrialInstitutionalMixed UseMulti-Optional DevelopmentPark and RecreationOpen Space or Restrictive Use

Rights-of-Way (i.e., Roads)Railway (inc. LRT)AirportVacant or UnknownOpen Water

Downs Lake SubwatershedMajor Subwatershed BoundaryVBWD Legal Boundary

Current (2010) Land Use Future (2030) Land Use

0

50

100

150

200

250

300

350

1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015

Jun

e-S

ep

t. A

vera

ge T

ota

l Ph

osp

ho

rus

(ug/

L)

Downs Lake June-Sept. Average Total Phosphorus

MPCA Shallow Lake Standard

0

50

100

150

200

250

300

350

1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015Jun

e-S

ep

t. A

vera

ge C

hlo

rop

hyl

l a (

ug/

L)

Downs Lake June-Sept. Average Chlorophyll a


0.0

0.2

0.4

0.6

0.8

1.0

1.2

1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015

Jun

e-S

ep

t. A

vera

ge S

ecc

hi D

isk

Tran

spar

en

cy (

m)

Downs Lake June-Sept. Secchi Disk Transparency


Figure 5.14-3

Downs Lake Water Quality 2015 - 2025 Waterhsed Management Plan


§̈¦94

456715456710

""95

""5 Lake Elmo Airport

Structure 2B

ToSt.CroixRiver

SunfishLake

GolfCoursePond

Durand'sPond

I- 94

30th St N

10th St N

Hudson Rd S

Man

ning A

ve N

Lake

Elm

o Ave

N

Hudson Blvd

Oak

green

Ave N

S Frontage Rd

Nea

l Ave

N

India

n Tr S

20th St N

Nea

l Ave

S

Nola

n Ave

N

4th St N

Midwest Tr N

Sti llwater Blvd N

6th St N

Manning Tr N

Nor

ell Av

e N

8th St S Cott

age G

rove D

r

Sti llwater La

Orw

ell Av

e N

5th St N

12th St N

24th St N

Newberry Ave N

32nd St N

22nd St N

Man

ning A

ve S

Lakeview Dr

26th St N

Legio

n Ave

N

27th St N

Oma

ha Av

e N

Oasis A

ve N

Novak Ave N

Tomahawk Dr S

2nd St S

Osp

rey Av

e N

Lisbon Ct

21st St N

Morris Rd N

Nor

dic A

ve N

Nor

thridg

e Ave

N

Legio

n La N

Greenwood Tr N

Lisb

on Av

e N

Nor

crest

Ave N

Men

del A

ve N

9th St N

3rd Street Pl N

Olen

e Ave

N

7th St N

Bob

Tr

4th St S

Lake

Ridg

e Dr

3rd St S

14th St N

Hil lside Ct

28th St N

13th St N

Overlook La N

31st St N

Nor

man A

ve N

Toma

hawk

La S

Klon

dike A

ve N

Laverne Ave N Layto

n Ave

N

33rd St N

Mark Ave N

Leeward Ave N

23rd St N

8th S

treet

Ct S

17th St N

Margo Ave N

Briar Glen La

Neal Avenue Ct N

Nordic Avenue Ct N

16th St N

Oldr

idge A

ve N

Oakgreen Avenue Pl

Northridge La N

11th St N 10th Street Ct N

30th

Stre

et Ci

r N

Lansing Ave N 4th Street Ct N

Mina

r Ave

S

Oakgreen Avenue Ct N

4th Street Cir N

Bayview La

18th St N

32nd St N

Oma

ha Av

e N

28th St N

Hudson Blvd

Nola

n Ave

N

33rd St N

Legio

n Ave

N

Nov

ak Av

e N

24th St N

Neal Ave N 21st St N

I- 94

Mendel Ave N

17th St N

Nor

crest

Ave N

24th St N

Nea

l Ave

N

Lisbon Ave N

3rd St S

26th St N

20th St N

Hudson Blvd

21st St N

LakeElmo

Lake Edith

Horseshoe Lake

Downs Lake

Legion Pond

Rest Area Pond

Rose

Bay Lake

Kramer Pond

Mergens Pond

Fahlstrom Pond

West Lakeland Storage Site

EdenParkPond

Lake

Barr

Foote

r: Date

: 9/3/

2004

1:02

:07 P

M F

ile: I

:\Clie

nt\Vb

wd\D

istric

t\Proj

ect\W

TRSH

D~1\F

IG51

4~1.M

XD U

ser:

lkp

Figure 5.14-4LOCATION MAP AND FLOW PATHS:

DOWNS LAKE STUDYValley Branch Watershed District

µScale in Feet

3,000 0 3,0001,500

LEGENDFlow Paths

Downs Lake Overflow PathsProject 1007 Flow PathsOverflow Path to Fahlstrom PondI-94 Stormwater Routing (Continuous)I-94 Stormwater Routing (Discontinuous)

20th Street North

ParkingLot

Durand'sPond

DownsLake

EdenParkPond

GolfCoursePond

Mannin

g T

rail

Nort

h

18th Stre

et North

Mannin

g A

venue N

orth

21st St N

Legio

n L

ane N

ort

h

Legion Ln Circle

Legio

n A

venue N

ort

h

Lisbon

Ave N

900

900

900

900

900 900

900

T A R T A N P A R K

G O L F C O U R S E

N

Scale in Feet

0 400 800

DATA SOURCES: - USGS Topographic (Quadrangle) Map- Mark Hurd 1978 2' Topo - Project 1007- 1997 Aerial Photograph- MNDOT CSAH No 15 Construction Plans (1964) Sheet 6 of 17- Barr Engineering Company Low Home Survey Data (~1987)

Dry Weather Water Level Extents

Projected 100-Year Flooded Area

Buildings Above 100-Year Flood Elevation,Numbers Refer to Table 5.14-2

Buildings Below 100-Year Flood Elevation,Numbers Refer to Table 5.14-2

900-Foot Elevation Contour Line900

Figure 5.14-5

100-YEAR FLOOD EXTENTSDOWNS LAKE AND SURROUNDINGS


1

2

34

5

6

7

8

9

10

11

12

13

14

1

3

P:M

pls

\23 M

N\8

2\2

382174\W

ork

File

s\2015 V

BW

D P

lan\P

lan S

ect

ions\

Sect

ion 5

\Additi

onal F

igure

s\S

ourc

e F

iles\

Fig

ure

5.1

4_5.C

DR

RLG

03-0

8-1

5

882

884

886

888

890

892

894

8961/1

/19

75

1/1

/19

77

1/1

/19

79

1/1

/19

81

1/1

/19

83

1/1

/19

85

1/1

/19

87

1/1

/19

89

1/1

/19

91

1/1

/19

93

1/1

/19

95

1/1

/19

97

1/1

/19

99

1/1

/20

01

1/1

/20

03

1/1

/20

05

1/1

/20

07

1/1

/20

09

1/1

/20

11

1/1

/20

13

1/1

/20

15

Ele

vati

on

(ft

, M

SL

)

Date

Water Level Spot records 100-Year Flood Level

Overflow to Eden Park Pond 1965 Estimated Water Level = 892

Figure 5.14-6

DOWNS LAKE WATER LEVELS 2015 - 2025 Watershed Management Plan


Observed data in NGVD29 datum

20th Street North

ParkingLot

Durand'sPond

DownsLake

EdenParkPond

GolfCoursePond

Mannin

g T

rail

Nort

h

18th Stre

et North

Mannin

g A

venue N

orth

21st St N

Legio

n L

ane N

ort

h

Legion Ln Circle

Legio

n A

venue N

ort

h

Lisbon

Ave N

900

900

900

900

900 900

900

T A R T A N P A R K

G O L F C O U R S E

N

Scale in Feet

0 400 800

P:M

pls

\23 M

N\8

2\2

382174\W

ork

File

s\2015 V

BW

D P

lan\P

lan S

ect

ions\

Sect

ion 5

\Additi

onal F

igure

s\S

ourc

e F

iles\

Fig

ure

5.1

4_7.C

DR

RLG

03-0

8-1

5

DATA SOURCES: - USGS Topographic (Quadrangle) Map- Mark Hurd 1978 2' Topo - Project 1007- 1997 Aerial Photograph- MNDOT CSAH No 15 Construction Plans (1964) Sheet 6 of 17- Barr Engineering Company Low Home Survey Data (~1987)

Dry Weather Water Level Extents

Projected 100-Year Flooded Area

Buildings Above 100-Year Flood Elevation

Buildings Below 100-Year Flood Elevation

900-Foot Elevation Contour Line

Figure 5.14-7

DOWNS LAKE FLOODDURATION REDUCTION PROJECT

Valley Branch Watershed District900

Figure 5.14-8

GOLF COURSE POND DRAWDOWNValley Branch Watershed District

Figure 5.14-9

21st STREET DRAWDOWN STRUCTUREValley Branch Watershed District

Figure 5.14-10

LEGION LANE DRAWDOWNValley Branch Watershed District

Appendix A-5.14 Additional Macrophyte Information

Water QualityMonitoring Location

Typha sp.

Typha sp.

Eleocharis sp.

Scirpus acutus

Eleocharis sp.

Elodea canadensis

Alisma subcordata

Scirpus fluviatilis

Polygonum amphibiumScirpus fluviatilisScirpus validus

Alisma subcordataPolygonum amphibiumRorippa palustrisSagittaria sp.Scirpus fluviatilisScirpus validus

Alisma subcordataGlyceria sp.Polygonum amphibiumRorippa palustrisSagittaria sp.Scirpus validusTypha sp.

Eleocharis sp.Polygonum amphibiumRorippa palustrisSagittaria sp.Scirpus fluviatilisScirpus validusTypha sp.

Polygonum amphibium

Alisma subcordataGlyceria sp.Polygonum amphibiumSagittaria sp.Scirpus fluviatilisScirpus validusTypha sp.

20th St

Manning Ave

Legio

n Ln

21st St

24th St15

0 60 120 180Meters

0 300 600Feet

Barr

Foote

r: Date

: 11/2

4/200

9 5:27

:55 P

M F

ile: I

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nt\VB

WD\

Distric

t\Map

s\Mac

rophy

teMap

s\200

9\Dow

nsLk

_Mac

rophy

tes_0

6050

9.mxd

Use

r: mb

s2

Imagery Source: 2008 AE

DOWNS LAKE MACROPHYTESURVEY RESULTS

June 5, 2009Valley Branch Watershed District

FIELD NOTES:- Macrophyte densities estimated as follows: 1=light; 2=moderate; 3=heavy- No macrophytes found in water >2 ft- Glyceria sp. sporadic around lake perimeter- Alisma subcordata, Rorippa palustris sporadic along shoreline

LegendEmergent PlantsFloating Leaf PlantsSubmerged Aquatic PlantsNo Aquatic VegetationCommon Name Scientific Name

Canada waterweed Elodea canadensis

Common Name Scientific Name

water smartweed Polygonum amphibium


manna grass Glyceria sp.cattail Typha sp.bog yellowcress Rorippa palustrishardstem bulrush Scirpus acutusriver bulrush Scirpus fluviatiliswater smartweed Polygonum amphibiumsoftstem bulrush Scirpus validuswater plantain Alisma subcordataarrowhead Sagittaria sp.spikerush Eleocharis sp.

Submerged Aquatic Plants

Emergent Plants

Floating Leaf Plants

!?Water QualityMonitoring Location

Typha sp.

Scirpus fluviatilis

Eleocharis sp.

Elodea nuttallii - 1-2

Scirpus fluviatilis

Polygonum amphibium

Scirpus fluviatilis

Scirpus validus

Polygonum amphibium

Scirpus fluviatilis

Scirpus validus (sporadic)


Polygonum amphibium

Sagittaria sp.

Scirpus validus

Typha sp.


Scirpus fluviatilis

Scirpus validus

Typha sp.

Polygonum amphibium

Polygonum amphibium

Scirpus fluviatilis

Scirpus validus

Typha sp.


Scirpus fluviatilis

Majority Phalaris arundinacea

20th St

Man

nin

g A

ve

Le

gio

n L

n

21st St

24th S

t

456715

!;N

0 80 160

Meters

0 300 600

Feet

Ba

rr F

oo

ter:

Arc

GIS

10.0

, 2

01

2-0

9-2

4 1

2:4

4 F

ile: I:

\Clie

nt\V

BW

D\D

istr

ict\

Ma

ps\M

acro

ph

yte

Ma

ps\2

01

2\D

ow

nsL

k_

Ma

cro

ph

yte

s_

06

05

12.m

xd

Use

r: k

ac2

Imagery Source: 2009 AE

DOWNS LAKE MACROPHYTESURVEY RESULTS

June 5, 2012Valley Branch Watershed District

FIELD NOTES:- Macrophyte densities estimated as follows: 1=light; 2=moderate; 3=heavy- No macrophytes found in water >2 ft

Emergent Plants



No Aquatic Vegetation

!? Water Quality Monitoring LocationCommon Name Scientific Name

Slender w aterw eed Elodea nuttallii


Water smartw eed Polygonum amphibium


Arrow head Sagittaria sp.

Cattail Typha sp.

Northern Mannagrass Glyceria borealis

Reed canary grass Phalaris arundinacea

River bulrush Schoenoplectus fluviatilis

Softstem bulrush Schoenoplectus tabernaemontani

Spikerush Eleocharis sp.

Water smartw eed Polygonum amphibium



Emergent Plants

list of tables - vbwd · estates developments are located east of the lake. approximately 20% of...

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