Frequently Asked Questions

Putting anything other than storm water in a storm drain is illegal. If you observe any illegal dumping please contact the Engineering Department immediately at 715-425-0900 or contact the Police Department after hours at 715-426-0909. If we can respond while the dumping is occurring or shortly after, we can hopefully contain it, prevent discharge to the river, and clean it up properly.

No, there are 53 known mosquito populations in the state of Wisconsin. Only one of those is the main carrier of the West Nile Virus (WNV), the Cultex mosquito. Cultex mosquitoes do not breed in deep ponds; they only lay their eggs in shallow stagnant water. They typically fly only 1/4 mile from where the hatch. Therefore, eliminating shallow, stagnant water will eliminate the breeding grounds for the Cultex mosquito.
The current standards of the City of River Falls call for storm water ponds to be at least four feet deep. The dry ponds and infiltration ponds within the City are designed to drain in 48 hours. Typically, mosquito larvae require four days (96 hours) to fully develop; therefore, the dry ponds and infiltration ponds are not wet long enough for mosquito breeding. For additional information, click here, or check out the following links: Wisconsin Department of Natural Resources Center for Disease Control (CDC) US Environmental Protection Agency National Pesticide Information Center Department of Health and Family Services WI West Nile Virus / Dead Bird Hotline: 1-800-433-1610

The development of an algae bloom depends upon local conditions and site-specific characteristics. But they generally occur where there are high levels of nutrients, principally phosphorus, together with warm, sunny and calm conditions. The main source of nutrients in Lake George is sediment, which has accumulated behind the dams since they were constructed over 100 years ago. This sediment resulted from poor upland soil conservation practices that were generally followed prior to 1960. What kinds of options are there for removing the algae? Is it harmful? Typically, the first steps taken target the control of the external sources of phosphorus and can include: encouraging the use of phosphorus free fertilizers; improving agricultural practices, reducing urban run-off; and restoring vegetation buffers around waterways. Lakes are very slow to recover after excessive phosphorus inputs have been eliminated. Furthermore, it’s extremely difficult to achieve recovery of lake conditions without additional in-lake management. This is due to the fact that lake sediments become phosphorus rich and can deliver excessive amounts of phosphorus to the overlying water. When dissolved oxygen levels decrease in the bottom waters of the lake (anaerobic conditions), large amounts of phosphorus trapped in the bottom sediments are released into the overlying water. This process is often called internal nutrient loading or recycling. Alum is used primarily to control this internal recycling of phosphorus from the sediments of the lake bottom that result in algae. On contact with water, alum forms a fluffy aluminum hydroxide precipitate called floc. Aluminum hydroxide (the principle ingredient in common antacids such as Maalox) binds with phosphorus to form an aluminum phosphate compound. This compound is insoluble in water under most conditions so the phosphorus in it can no longer be used as food by algae organisms. As the floc slowly settles, some phosphorus is removed from the water. The floc also tends to collect suspended particles in the water and carry them down to the bottom, leaving the lake noticeably clearer. On the bottom of the lake the floc forms a layer that acts as a phosphorus barrier by combining with phosphorus as it is released from the sediments. For additional information, click here.

Get the Facts! We found a great information sheet out of New Hampshire that explains how seal coat can be dangerous and what to do about it. Coal-tar and asphalt based sealants are used across the nation to protect and beautify parking lots, roads and driveways. These sealants are used commercially and by homeowners on driveways, playgrounds, and parking lots. Scientific studies have identified coal-tar sealcoat (CTS) as a major source of polycyclic aromatic hydrocarbon (PAH) contamination in urban areas for large parts of the nation. PAHs are a concern because several are suspected or probable human carcinogens and are also toxic to aquatic life. The research is still ongoing with regard to PAHs and there are no acute or chronic exposure levels in the US at this time. Other communities are noticing elevated levels of PAHs in their storm water pond sediment and are finding that is it very costly to properly dispose of this contaminated sediment. In River Falls, we have over 90 storm water management ponds that collect sediments prior to water discharging to the river. Asphalt based sealants are similar to coal tar in their use and application. Asphalt sealants are also cheaper than CTSs; however, their effective life is shorter at 4-6 years as opposed to 8-10 years. The main advantage is that pure asphalt sealants are not carcinogenic. Due to the significant cost of PAH-contaminated sediment disposal, the use of CTSs could have future financial impacts on the City. We are asking for your cooperation in using asphalt based sealcoat if you choose to sealcoat your driveway or parking lot. If you are hiring a professional, ask which type of sealant they use.

The City of River Falls does not require a permit to discharge pool water. To protect the environment, the following “Best Management Practices” apply to water discharged from swimming pools and hot tubs: • It is recommended that discharge water be directed to grass and/or landscaping. • If irrigating on site is not possible, water may be discharged off the owner’s property, provided it is directed to a curbline gutter of a paved street. How to drain your pool or spa: • Prior to irrigating or disposing of the water, shut off the chlorination system (if you have one) or stop adding chlorine. • Let the water in the pool or spa “sit” for at least one week to reduce the chlorine or bromine level until it is undetectable and temperature is at air temperature. Discharging chlorinated pool/spa water into streams in harmful to fish and other aquatic life. • Measure the pH. It should fall within a range of 6.5-8.5 prior to discharge. Discharge water should not be cloudy or discolored as this typically indicates a pH imbalance. • As the water is discharging, it must be monitored to ensure that it does not cause any erosion or flooding. Erosion is most likely to occur at houses on a bluff that discharge to the rear yard down the steep slope. • Discharges may not run onto a neighbor’s property or across a sidewalk • If a pool or spa has been acid washed, the water may not be discharged off the pool/spa owner’s property. • Water from backflushing pool filters should not be discharged to a stream, ditch or storm sewer. Backflush from pool filters must be discharged to the sanitary sewer or on-site septic tank and drain field system.

As rain falls to the ground it becomes known as storm water. Storm water that falls on pervious surfaces (grass, fields, natural areas, etc.) soaks into the ground without running off into streams and lakes. Storm water that falls on impervious surfaces (roofs, driveways, roads, sidewalks, etc.) is not allowed to soak into the ground and runs off into streams and lakes. As land is developed, trees are cleared and houses, buildings, and parking lots replace them. Runoff on hard surfaces occurs faster and in greater volumes. Increased runoff can create erosion problems, increase water pollution, and destroy stream habitat. Impervious surfaces also reduce groundwater recharge, which is a critical factor for cold-water streams such as the Kinnickinnic. Check out our information sheet to find out about different types of storm water management features that the City utilizes to improve the effects of storm water.

Yes, there are many different types of pervious pavement, for more information about a few of them check out our fact sheet on pervious pavements .