Stormwater runoff from snow on a road showing damage.

With increasing development and growth we have changes in water quantity and water quality within a watershed. Changes in water quantity result from alterations in a sites physical environment. This is caused by an increase of the impervious area on the site, a decrease in the vegetative cover, and alterations to the slope. Changes in water quality result from transformations in land use that contribute new or additional pollutants to runoff (EPA, 1992). Together, these are defined as stormwater runoff.

As we have more development of rooftops, driveways, streets, and other hard surfaces, runoff increases and drainage patterns change significantly. Because of these changes, it is necessary to provide and enforce stormwater controls and Best Management Practices (BMPs) to reduce stormwater pollution. There are two basic types of pollution, point and non-point source pollution. Point source pollution is defined as pollution coming from a single source, like a pipe. Non-point source pollution, is pollution coming from an accumulation of many different sources with no single identifiable source or specific outlet. Non-point source pollution is the most important source of pollution to control because it is the most difficult to manage and can be the most detrimental to our lake, streams, river and aquifer. For instance, in the Liberty Lake area, non point sources include: runoff from roads, residential areas, and surrounding mountains. Point sources include: drainage channels from roads, natural drainages and existing springs.

There are many non-point source pollution controls in place in residential areas such as stormwater swales and stormwater barriers (silt fences). A stormwater swale is a depression that collects stormwater runoff from streets, driveways and rooftops. They are designed according to the area of impervious surface, and dispose of stormwater through an infiltration process. Water soaks into the ground through the pore spaces in the soil of the swale and eventually recharges the groundwater (aquifer) (Spokane County Informational Handout). Silt fences are another means of protection from stormwater. Silt fences are constructed from geotech fabric and are designed to prevent sediment from becoming runoff at construction sites where excavation has occurred. Minimizing contaminant sources from both point and non-point sources is positively the best long term solution to protecting the quality of water.

Since the late 1800’s, Liberty Lake has experienced a steady population growth within the watershed. Due to this growth, the natural eutrophication process of the lake was being speeded up by human activities. The deterioration resulted in a lake restoration plan to address the need to protect and preserve the water quality of the lake. As part of this restoration plan, the Liberty Lake Sewer District adopted its first ordinance for stormwater management in 1981. This ordinance was updated in 1985, 1987, and 1992. In 1994, the district received a Washington State Centennial Clean Water Grant to develop a stormwater management plan. The district authorized Century West Engineering Corporation to proceed with the preparation of a Comprehensive Stormwater Management Plan in 1996. As part of this Comprehensive Stormwater Management Plan, the district has the authority to provide for the reduction, minimization, and/or elimination of pollutants from lakes, rivers, and groundwater, including those contained in stormwater; pursuant to RCW 57.08.005(8) (Century West, 1998).

The comprehensive plan is designed to provide guidance and criteria for establishing and maintaining water quality within the Liberty Lake Sewer District’s boundary and the lake’s watershed. Focus is placed on:

  • Reducing point and non-point source pollutant loads being discharged to receiving waters in order to protect or restore beneficial uses and meet water quality standards
  • Reducing the damages caused by flooding and inadequate flood hazard management
  • Reducing flushing of the marsh waters into the lake to protect beneficial uses and meet water quality standards
  • Educating residents, landowners, developers, and contractors about accepted stormwater best management practices and how they can affect the water quality within the watershed
  • Preserving the natural watershed to reduce flooding impacts and meet water quality standards

Lawn Fertilizer

Fertilize with Care! If your must fertilize, do not use phosphorus compounds! The soils at Liberty Lake have adequate phosphorus naturally. So if you must fertilize, and for the protection of the lake, aquifer and environment, “fertilize with care”. How do you compute the amount of phosphorus in a bag of fertilizer? Generally there are three numbers on the fertilizer bag, i.e. 18-0-10. The first number is the percent of nitrogen (N), the second number is phosphorus (P), and the third number is potash. It is the second number, phosphorus, that can find its way back to streams, rivers, and lakes causing excessive aquatic growth. Find fertilizers with zero phosphorus (P). It is recommended to fertilize lightly four (4) times per year using the holidays Easter, Memorial Day, 4th of July and Labor Day as reminders. Always apply fertilizer according to the manufacturers recommendations. Excessive use of fertilizer will not be used by the plants and tends to migrate to ground and surface waters. Hire a professional if possible and insist on phosphorus-free fertilizer. Ask you local distributor to stock phosphorus-free fertilizer for the Liberty Lake area.

Phosphorus Lawn Fertilizer No Use Policy

The Liberty Lake Sewer and Water District has recognized the need to protect the lake, surface and groundwater and has adopted policies, guidelines and recommendations for that purpose. In an effort to reduce pollutants that contribute to algae blooms and water quality deterioration, the Liberty Lake Sewer and Water District is discouraging the use of lawn fertilizers that contain the element Phosphorus within the watershed of Liberty Lake. Phosphorus is one of the key elements necessary for growth of plants and animals, however phosphorus can cause environmental impacts if an excess of phosphate enters the waterway. This condition is known as eutrophication or over-fertilization of receiving waters. The rapid growth of aquatic vegetation can cause the death and decay of vegetation and aquatic life because of the decrease in dissolved oxygen levels.

Phosphorus Lawn Fertilizer No Use Policy Resolution # 46-05

LLSWD Stormwater Requirements

The Stormwater Resolution 26-13 as approved on July 16, 2013, provides the Liberty Lake Sewer and Water District the authority to require a policy for stormwater management within the district boundaries. These policies include, a Stormwater Drainage Plan and Review, and a Stormwater Permit. In the event of a Stormwater Drainage Plan, the district has the authority to issue a review and inspection fee of $600 for the plan review and inspection of stormwater swales. The fee covers the initial plan review, one additional submittal, a check of the final plan, and three site drainage inspections (rough, preliminary-final, and final). Any additional plan review and inspection will we billed to the homeowner at actual costs per hour.

  • If these best management practices are followed, we can all help preserve the natural Liberty Lake watershed and protect the beneficial uses and the quality of our water.

For information on development near the shoreline, visit our Shoreline Protection page