The City of Hopkins has developed this Water Resources Management Plan (WRMP) to meet regulatory requirements and to plan for future alterations in existing drainage system redevelopment activities.
The City of Hopkins is within the Minnehaha Creek Watershed District (MCWD) and the Nine Mile Creek Watershed District (NMCWD). The MCWD updated its Water Resources Management Plan in 1997, and the NMCWD updated its Plan in 1996.
The City of Hopkins is completely developed with a mix of commercial, industrial, residential and open space uses. Redevelopment activities within the City are also occurring as the population of the surround area continues to grow.
Location
The City of Hopkins lies in southeast Hennepin County. The City contains 2,760 acres of land and water resources within its corporate boundaries and is bounded by the cities of Minnetonka, Edina, and St. Louis Park
Future Land Use
As previously stated, the City of Hopkins is completely developed. The future land use as defined in the updated Comprehensive Plan is shown in Figure 0. The future land use changes will be a result of development activities. Future redevelopment activities should not have a significant impact on regional storm water systems.
Shoreland
The City of Hopkins has not adopted a shoreland ordinance. At this time, the Mn/DNR does not require a shoreland ordinance, and we do not see the need to implement one in the near future.
Floodplain
The City participates in the National Flood Insurance Program (NFIP). The City administers a floodplain ordinance based upon the effective Flood Insurance Study (FIS) for the City of Hopkins (dated June 16, 1992). There are two flooding sources (Minnehaha Creek and Nine Mile Creek) shown in the FIS. A request for a letter of map revision (LOMR) has been submitted to the Federal Emergency Management Agency (FEMA) for consideration. This LOMR is for a correction of an inconsistency found in the with floodway version for the Duplicate Effective Model that had been furnished by the DNR in August 1994. The roadway overflow section at 9 th Avenue South had not been encroached to be consistent with the floodway width downstream and upstream of the crossing. This correction requires that corrected duplicate model be prepared.
Surface Water Resources
The National Wetland Inventory Map shows the location and type of wetlands within the City of Hopkins. In addition to these basins, there are several storm water detention basins within the City limits, which provide some of the benefits of a natural wetland basin.
There are three Protect Waters and Wetlands. Mn/DNR Nos. 27-717W, 27-777P, and 27-779W) within the City of Hopkins. There is a portion of another protected water MN/DNR No. 27-048P in the northern section of the City. This protected water is also shared by the City of St. Louis Park and Minnetonka.
Creeks
Minnehaha Creek
Minnehaha Creek is a direct tributary to the Mississippi. Lake Minnetonka is the headwater of the creek. It is a Mn/DNR watercourse and flows east at the north end of Hopkins and south on the east side of the City.
Nine Mile Creek
The headwater of the north fork of Nine Mile Creek is north of Excelsior Boulevard in the southwest portion of Hopkins. Nine Mile Creek flows southeast to the Minnesota River. It is a Mn/DNR protected watercourse.
General Drainage Patterns
The City of Hopkins lies within the MCWD and the NMCWD. The northern and eastern portion drains to Minnehaha Creek, while the southern and central portions of the City drain to Nine Mile Creek.
Land-Locked Areas
The City of Hopkins does contain land-locked areas. A land-locked area is one which will not drain naturally no the ground surface. An outlet for each of these areas should be considered to decrease the flooding potential.
Hydrologic Modeling
HydroCAD modeling has been created for specific studies within the City of Hopkins, but there has not been a hydrologic model created for the entire City.
Design Storm
The 24-hour duration, Natural Resources Conservation Service (NRCS) Type II rainfall distribution with average soil moisture conditions (AMC-2) will be used for overall subwatershed planning within the City of Hopkins. The rainfall depths for storms associated with various return periods is shown below. This criteria is consistent with the MCWD Water Resources Management Plan, the NMCWD 509 Plan, and guidance from the NRCS. More recent date developed by Huff and Angel (1990) vary somewhat from these values.
| Rainfall Depth for 24-hr Event (USWB TP-40) |
|
|---|---|
| Return Period | Rainfall Depth (inches) |
| 1-yr | 2.3" |
| 2-yr | 2.8" |
| 3-yr | 3.6" |
| 5-yr | 4.2" |
| 50-yr | 5.3" |
| 100-yr | 6.0" |
Soils
The surficial geology of the Hopkins area consists of unconsolidated sediments of glacial deposits, derived from the Des Moines Lobe, Gransburg Sublobe, and a small amount from the Superior Lobe. The glacial sediments were deposited during the most recent glacial event, the Late Wisconsinian, which ended about ten thousand years. Ago. These deposits consist of till and outwash deposits.
Surficial Hydrogeolgy
The unconsolidated glacial deposits range in thickness from 50 to 250 feet within the City of Hopkins. The water from the local groundwater table in most easily obtained from outwash deposits with broad areas of till acting as confining layer. Groundwater flow in the unconsolidated glacial deposits in generally east toward the Mississippi River. The water table is approximately 900 feet above mean sea level.
Bedrock Geology
As state above, the depth to bedrock ranges from 50 to 250 feet in the City of Hopkins, the City of Hopkins sits on the western side of the Town City basin, a bowl-like structure in the bedrock. At this location, the bedrock strata dips gently toward the east. The youngest and straigraphically highest bedrock underlying the City of Hopkins is the Plateville and Glenwood formations. Underlying the Plateville and Glenwood formations is the St. Peter Sandstone, which along with the Plateville and Glenwood formations, make up almost all of the uppermost bedrock of the City.
Bedrock Hydrogeology
Four major bedrock aquifers underlie the City of Hopkins. They are the St. Peter Sandstone, Prairie du Chien-Jordan, the Franconia-Ironton-Galesville, and the Mount Simon-Hinckley. These aquifers are separated by lower permeability confining layers. The first encountered confined bedrock aquifer is the St. Peter Sandstone, the second aquifer is the Prairie du Chien-Jordan Aquifer. The St. Lawrence Confining Layer separates the Prairie du Chien-Jordan Aquifer from the underlying Franconia-Ironton-Galesville Aquifer. The Eau Claire Confining Layer separates the Franconia-Ironton-Galseville Aquifer from the deepest aquifer, the Mr. Simon-Hinckley Aquifer. The ground water flow direction in the bedrock aquifers is generally southeast in the Hopkins area.
The St. Peter Sandstone is the first encountered confined bedrock aquifer. The upper part of the formation consists of fine to medium grained friable quartz sandstone. The lower part of the St. Peter Sandstone contains multicolored beds of mudstone, siltstone and shale with interbedded very coarse sandstone. Many sand grains in the lower part are dark gray in color.
The Prairie du Chien-Jordan Aquifer is made up of the Prairie du Chien Group and the Jordan Sandstone. The Prairie du Chien Group consists of a sandy dolostone with minor amounts of shale. The Jordan Standstone is a fine to coarse grained quartzose sandstone with minor amounts of shale. The Prairie du Chien-Jordan is the most heavily used aquifer in Hennepin County, with potential yields to 1,000 to 2,000 gallons per minute. Underlying the Prairie du Chien-Jordan is the St. Lawrence Confining Layer. The St. Lawrence is comprised of lower permeability siltstone and dolostone and acts to hydrologically separate the overlying Prairie du Chien-Jordan from the underlying Franconia-Ironton-Galesville.
The Franconia-Ironton-Galesville Aquifer is made up of the Franconia Formation, comprised of glauconitic sandstone with some shall and dolomite; the Ironton Sandstone, and the Galesville Sandstone. This aquifer is commonly used for domestic water supply wills in the north and northwestern portions of Hennepin County. Underlying the Franonia-Ironton-Galesville is the Eau Claire Confining Layer. The Eau Claire consists of siltstone, shale, and silty sandstone and serves to hydrologically separate the overlying Franconia-Inonton-Galesville form the underlying Mount Simon-Hinckley.
The Mount Simon-Hinckley Aquifer is made up of the Mount Simon and Hinckley Formation. The Mount Simon Formation is a silty, fine-to course grained sandstone with thin beds of very fine-to fine-grained sandstone and minor shale beds. The Hinckley is absent in most places, but where it occurs it is in remnants only several tens of feet thick.
Recharge Zones
Recharge to the bedrock aquifers beneath the City of Hopkins occurs in two ways, vertically and laterally. Vertical recharge occurs through overlying glacial sediments and other bedrock aquifers. Lateral recharge occurs as ground water moved laterally from outside the City or County, through the aquifer. The lateral recharge to the bedrock aquifers in Hopkins come from the west.
Recharge to the Water Table Aquifer occurs primarily from precipitation and surface water groundwater interaction as will as laterally from outside the City.
Local Groundwater Models
The Hennepin County Conservation District (HCD) in cooperation with the Minnesota Department of Health has developed a County wide multi-layer groundwater model. This model may be a valuable tool in dealing with many of the Hopkins groundwater issues. This model could be useful with issues such as; wellhead protection, storm water infiltration ponds, wetland issues, well siting, dewatering, etc.
The Minnesota Pollution Control Agency (MPCA) is currently developing a Metropolitan Groundwater Model. This model is a regional model focusing on the seven County metropolitan area including Hennepin County. The focus of the MPCA model is more for evaluation groundwater contamination and remediation of the Quaternary aquifer and the Prairie du Chien Aquifer. The MPCA model and the HCD model utilize the Multi-Layer Analytical Element Model (MLAEM). The HCD model however is characterized as a single layer.
A goal is a desired end toward which water management efforts are directed. This section of the plan identifies nine goals for water resources planning and management functions. The goals of this plan were established in accordance with the goals of the Minnehaha Creek Watershed District and the Nine-Mile Creek Watershed District which have jurisdiction in Hopkins.
Each goal has several corresponding policies. A policy is a governing principle that provides the means for achieving established goals.
| Summary of Goals | ||
|---|---|---|
| Goal No. | General Goal Category | Goal Statement |
| 1 | Water Quantity | Control flooding and minimize related public capital and maintenance expenditure necessary to control excessive volumes and rates runoff. |
| 2 | Water Quality | Achieve water quality standards in creeks and wetlands consistent with intended use and classification. |
| 3 | Erosion Control | Minimize or control soil erosion through enforcement and education. |
| 4 | Wetlands | Maintain the mount of wetland acreage, increase, and achieve "not net loss" of wetland values within the City, where feasible. |
| 5 | Public Participation, Information and Education |
Increase public participation and knowledge in management of the water resources. |
| 6 | Maintenance and Inspection | Preserve the function of water resource facilities through routine inspection and regular maintenance activities. |
| 7 | Recreation, Fish and Wildlife | Manage water recreation activities and improve fish and wildlife habitat, enhancement, and protection. |
| 8 | Ground Water | Prevent contamination of the aquifers and promote groundwater recharge. |
| 9 | Finance | Establish funding sources to finance water resources management activities. |
The Implementation Section is intended to provide guidance in carrying out the objective. The implementation program summarized the schedule for the cost of recommended actions. Lastly, procedure for amending the plan are discussed in the table below summarizing the Implementation Schedule for the Hopkins WRMP.
| Hopkins WRMP Implementation Summary | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | |
| Adopt Hopkins WRMP | X | |||||||||
| Adopt Water Mgt. Ordinance | X | |||||||||
| Design Standards | X | X | X | X | X | X | X | X | X | X |
| Administer Land Use Controls | X | X | X | X | X | X | X | X | X | X |
| Capital Improvements | X | X | X | X | X | X | X | X | X | X |
| Storm Water Utility | X | X | X | X | X | X | X | X | X | X |
| Information and Education | X | X | X | X | X | X | X | X | X | X |
- Minnesota Wetland Conservation Act to be administered by MCWD and NMCWD
- FEMA has reviewed the City of Hopkins to determine flood prone areas.
- MCWD Communication's Committee and the NMCWD Advisory Committee to take the lead in information and education activities.
The implementation plan includes identification and prioritization of capital improvements, administration, inspection, permitting, plan amendments, financing alternatives, public involvement and monitoring programs. Prioritization of improvements is based on a review on all recommended actions.
Planning-level estimated of capital expenditures have been made. Future anticipated projects are also listed. The activities have been distributed through a 10-year implementation plan extending through 2008.
The Implementation Plan is not a hard and fast commitment to complete each and every activity in the time frame suggested. Rather, it is a suggested course of action that will accomplish the major goal of this plan, to accommodate growth in the Community while protection the environment.
The Implementation Plan should be reviewed on an annual basis. At that time each proposed improvement is to be reconsidered, City budget adjusted, and additional improvement added to the program.
