Little Rock Lake-Sartell Pool Drawdown Project Information

A summer drawdown at Sartell Dam will be conducted Aug. 1 – Sep. 15 2018.

Questions, concerns or thoughts raised at the Public Hearing 3-28-2018

  • A Board of Water and Soil Resources (BWSR) Grant was awarded in December for the total of $198,250. This grant requires a 25 percent in-kind match, so the actual payment from BWSR will be approximately $166,250, the matching amount is $68.750.
  • To date, Eagle Creek Energy has contributed $30,000 toward the community match.
  • Little Rock Lake Association has raised more than $15,000, in addition, there are other pending contributions of over $25,000. The goal is to raise $60,000 to account for the match and other expenses such as plants, clean up efforts etc.
  • As mentioned previously, Federal Energy Regulatory Commission (FERC) license agreements and requirements dictate that the water cannot be lowered faster than 0.10 foot per hour (Roughly 30 hours to draw down 36 inches). For refilling, no more than 0.20 foot per hour or 10 percent of incoming flow, whichever is less (less than 30 hours for refilling).
  • Downstream and upstream areas will not be significantly impacted since the flow rate does not change much to accommodate the drawdown.
  • The water level at an individual location may vary along the calculated 11 miles of river with the three foot drawdown at Sartell Dam. There is an upper riffle area (imagine an underwater dam) just downstream of the Rice Bridge. That riffle location will likely be the upper extent of major effects of the drawdown on the Mississippi River.
  • Little Rock Lake will likely have about 4 feet of drop in the upper most end near Benton Beach (this could expose several hundred feet of sand/mud flats).
  • While the direct benefit to river properties will not be as great, shoreland plant expansion can help dramatically with erosion problems. We are asking for patience and goodwill for their neighbors and the entire community, as an attempt is made to correct changes that have occurred in the lake and in the watershed since the late 1800's. Continued efforts will be made to address septic, farm and urban runoff issues in the entire area.
  • Excavation of the beds of the lake and river channel are prohibited during the drawdown. Solid waste and debris removal is allowed by hand. Please remember that submerged rocks and wood both provide habitat for fish and other aquatic species.
  • Shoreline restoration projects that are planned during the drawdown should contact the DNR area hydrologist for review of the proposed plans prior to doing any work to ensure compliance with state rules and regulations. Permits may be required.
  • During the drawdown, residents will be allowed to rake the newly exposed surface to keep plants from growing in an area 50 feet by 50 feet (2,500 square feet) to maintain access. A 15 foot wide navigational access channel (through submerged aquatic vegetation may be maintained to navigable water or a water depth of 4 feet, whichever is less. However, there are guidelines that need to be followed to avoid violations or permit requirements.
  • Do I need a permit?
  • Information on maintenance to boat ramps
  • Resources on shoreland plants and shoreline restoration
  • Guide to invasive plants
  • Guide to native plants
  • During the drawdown, the entire lake will have a no-wake restriction. Wake restrictions on the river are still up for discussion, but changes are not likley. Signs will be posted at access points reflecting the hazards and duration of the drawdown on the lake and river.
  • Public accesses will have work performed to allow continued use during the drawdown.
  • There will likely be odors during the first week of the drawdown due to exposed sediments. After initial drying, odor is not expected to be significant.
  • While there may be small areas with some level of fish entrapment, it is not believed to be extensive at all. Fish migrate naturally and generally avoid areas of low oxygen or lack of water. Fish have been seen migrating in shallow water where only their heads were under water. Any fish that do become trapped will likely provide other wildlife viewing opportunities (for example, eagles and osprey or fish eating mammals).
  • A local commercial fisherman has expressed interest in harvesting carp during the drawdown; however, the market is generally not good during the summer and access to the fish may be problematic during the open water season.
  • Little Rock Lake Association will continue to have a carp contest on the lake each summer in early June.
  • Shoreline video, aerial images, aerial video, photos and locations of seep areas will be monitored during the drawdown. Including potential septic influences.
  • Reminder notices will be sent to all potentially affected residences along the river and lake prior to the drawdown.
  • After the drawdown, a workgroup made up of shoreline residents, community members and professionals will develop criteria, such as water clarity, phosphorus content, and aquatic habitat health to use when considering future drawdowns.
  • If there are additional questions, please contact Eric Altena (MNDNR), Kellie Gallagher (LRLA), Amanda Guertin (Benton SWCD) or Kevin Winkelman (Eagle Creek Renewable Energy)

Feasibility study that explains much of the history and projects related to the potential drawdown. 

 Common questions about the drawdown

The Sartell Dam was built in 1907, which increased the water level over 15 feet in some places, from normal Mississippi River water levels. Little Rock Lake water levels increased over 7 feet. When areas are flooded for that long of a time, plant growth is held back. This lack of root mass and shore stability due to those same roots decaying, allows for increased erosion to take place and less nutrients in the water to be processed. In addition, a significant change took place the way the Little Rock Creek watershed (and the rest of Benton County) was used. Historical records and pre-settlement maps suggest that all of Benton County was shrub and forested prior to land conversion for use by cities, businesses, homesteads and agriculture. This change of a once wetland basin (where Little Rock Lake is now), to a larger lake, absorbed significant nutrients over time. A drawdown or lowering of water can help to regain some of that plant material, while allowing some of the nutrients to be processed. The intent is to improve water quality, shoreland stability and increase fish/wildlife habitat. Drawdowns have been done throughout the country and Minnesota with impressive success.

 

  • Why do a drawdown? 
  • What are other potential options that could help water quality, habitat and shoreland stability?   Really, none that address most of the issues being faced. However, options such as filtration, dredging, barley/straw, Vegetative Mats, and Aluminum Sulfate (Alum) were considered. Each has value, however, all come with pros and cons.
  • Filtration would place a filter on the inlet creeks that prevents excess nutrients from getting to the lake. While this would be a good thing to do, it has not been used at this large of a scale or with sediment rich systems like the Little Rock Creek watershed. It has been effective in sewage treatment applications, but with smaller volume and less sediment. 
  • Dredging is by far the most expensive at roughly $12-$18 per cubic foot. Costs would likely exceed $20 million for Little Rock Lake. Dredging also does not treat the existing sediment where dredging does not occur. In fact, it may actually stir up additional nutrient rich sediment. This method also does not help fish and wildlife habitat, shoreland stability and may not improve water clarity. 
  • Vegetative Mats could be effective in reducing phosphorus in the water column, but would require half (or more) of the lake to be covered, to treat the basin. Costs are unclear, however, native plants are usually used and tend to be expensive for plugs. This method has never been tried at a large scale, only on small urban ponds and golf course hazards. 
  • Barley bales actually can work to reduce the effect of excess phosphorus on water clarirty by preventing the algal growth, however, this has shown only limited success in smaller (less than a few acres) basins. It also only treats a symptom (water clarity). Additionally, coverage would need to exceed 50% of the lake surface area to be even remotely have an impact.
  • Alum (Aluminum Sulfate) treatment is expensive ($450.00/acre) and also does not effectively treat the issue, it merely covers it up for a few years. It has also shown limited success in shallow, wind mixed, basins like Little Rock Lake. If we applied it to an area greater than 3 feet deep in the lake, the cost would be roughly $507,000.00 
  • Another potential option we looked into was a temporary coffer that would isolate the lake using water inflatable tube dam. Several manufacturers make the products. A potential option may include the use of a temporary dam and pumping after a short (4-5 day) drawdown for a longer term drawdown, within Little Rock Lake and the channel area. While this option seems feasible, there is significant liability associated with blocking off a 70,000 acre watershed and flood risk.
  • How far would the proposed drawdown bring water levels? The intent is for a lowering of the level at Sartell Dam for a total of six weeks. Or a short term drawdown to facilitate a temporary coffer installation. There will be some localized differences throughout the Mississippi River, likely near the Rice Bridge, however, the slope of the pool would likely maintain the three foot drop through most of Little Rock Lake and the Sartell Pool. There are maps below that show the potential level at various areas around the lake and river.
  • When is the potential drawdown going to happen?     Provided all significant approvals by state, federal and local authorities are met, a reasonable level of public support and the funding required to make it happen; the drawdown would be scheduled for early August 2018 through mid-September 2018.
  • How fast would it be lowered and raised again? Federal Energy Regulatory Commission (FERC) license  agreements and requirements dictate that the water cannot be lowered faster than 0.10 foot per hour (Roughly 30 hours). For refilling, no more than 0.20 foot per hour or 10% of incoming flow, whichever is less (less than 30 hours).  
  • Will the drawdown affect my well?  Extremely unlikely. The vast majority of private wells in the area are greater than 50 ft below the surface. Separate lenses of soil and clay make distinct layers between surface water and ground water. Even with a drawdown, the aquifers that are used for drinking water would not be affected.
  • Will I still be able to use my boat?  Yes. While the level would be lower than we are used to, there will still be significant water for recreation and angling. A note of caution: Objects that were previously out of reach by most boats may become hazards with a drop in water level. Public access sites will have maintenance performed during this time to allow continued use.

Detailed maps below!

Water quality is an issue on Little Rock Lake. A TMDL was established for the lake in 2011 for excessive nutrients. Water clarity at times is less than a few inches due to pervasive algal blooms. 

 

 Close up of algae bloom on Little Rock Lake.A picture of Little Rock Lake looking west at a peak algae bloom in summer.

Many efforts have been made in the watershed to try and address the source of excess nutrients including: alternative farming, irrigation, manure management and septic system upgrades. Despite these improvements there are still water quality issues on the lake. Something more large-scale needs to be done to address the problem. 

The 2012 TMDL report suggests a large portion of the higher phosphorous loading has come in during spring runoff events and then remains resident in the lake basin (Internal Loading). None of the suggested alternatives have attempted to address internal phosphorous loading. 

Benton County Little Rock Lake TMDL Page

Drawdowns have been shown as effective methods to process nutrients in the soils, stabilize shorelines, increase water clarity/quality and provide valuable fish/wildlife habitat. The proposal would be for six weeks, likely starting around the second week of July through the end of August 2018.  It will affect recreation to some extent in both the Mississippi River up to the Rice Bridge (County Road 2), Little Rock Lake itself and will likely make navigation through the Harris Channel extremely limited.

Pictures from the Mississippi River Pool 8 Drawdown, 2001 and 2002.

Drawdowns have been used throughout the country and in Minnesota as a management tool to improve fish/wildlife habitat, improve water quality and manage nuisance vegetation or fish. Typically, a frequency of summer drawdowns every 7-10 years has been proven effective at maintaining water quality and habitat standards. However, each reservoir complex is different.

The Sartell pool and Little Rock Lake have an artificially maintained stable water level that has not changed since 1908, when the dam at Sartell was installed.  Natural systems have a natural rise and fall which builds stability in the sediments and plant growth. Little Rock Lake and the Sartell Pool are still adjusting to this day. 

 

Some potential submerged vegetation growth may occur in areas that may not have been visible in the past. There are provisions within the DNR Aquatic Plant Management Program (APM) to control certain areas and types of plants without a permit. Please see APM Permit Information

Little Rock Channel and 15 miles of the Mississippi River (Two Rivers Campground- Sartell Dam) were mapped late April-early May 2016 and maps were created with the help of Biobase. Little Rock Lake was also mapped in May.  The information was used to calculate more accurately how much area will be exposed if or when a drawdown does occur. The information is available on the Insight Genesis website in a downloadable format for Lowrance units. it is available as a "Social Map" on the Insight Genesis website.

River and Lake Contour Maps in PDF format from Two Rivers Campground to Sartell Dam in order from upstream to downstream 1:5000 view. Each map shows the areas that would be exposed if there was a three foot drawdown. Also shown are single foot contours of the river and Little Rock Lake.
River Map 1River Map 9River Map 17River Map 25
River Map 2River Map 10River Map 18River Map 26
River Map 3River Map 11River Map 19Lake Map - Upper 
River Map 4River Map 12River Map 20Lake Map - Middle 
River Map 5River Map 13River Map 21Lake Map - Lower
River Map 6River Map 14River Map 22Lower Basin - North 
River Map 7River Map 15River Map 23Lower Basin - South
River Map 8River Map 16River Map 24Harris Channel

 

Where is the process now - January 2018?

  • Presentations have been given to Little Rock Lake Association, Rice Sportsmen's Club, River Property owners, City of St. Cloud, Mississippi Partners, Stearns County, Benton County, Anoka Sandplain Partnership and City of Sartell. Public meetings have been held, comments received and addressed to the best of our ability.  
  • Lake association and involved stakeholders are developing a funding plan to work with Eagle Creek Energy to accomplish the drawdow in the summer of 2018- Augst 1-September 15.  
  • As of January 2018, The Board of Soil and Water Resources Grant for the drawdown has been approved.

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