What Kinds of Best Management Practices Work Best?

Most Lake Tahoe residents and second-homeowners know that best management practices (BMPs) are required on all private and public properties at Lake Tahoe. They also know that these land management practices are designed to prevent the kinds of water pollution that are slowly but steadily reducing Lake Tahoe’s world famous water clarity. But, property owners want to know what kinds of BMPs they should install.

As we have discussed in previous articles, property owners need to evaluate their properties to learn if polluted runoff escapes the boundaries during a heavy rainstorm. It should not do so. The main goal of BMPs is to keep precipitation that falls on a property from running off, even during an intense rainstorm that drops an inch of rain in an hour. The rain should soak into the ground instead of running off the driveway and onto the street or down a hill toward a creek or roadside ditch.

The good news is that homeowners can receive a free BMP site evaluation by calling the Nevada Tahoe Conservation District in Nevada, (775) 586-7223, Ext. 1; or the Tahoe Resource Conservation District in California, (530) 543-1501, Ext. 6. You can schedule the free inspection when you are at home or away from home. If you are a business owner, you can call the TRPA, (775) 588-4547, Ext. 205. The evaluators are not looking for infractions of local rules. Their purpose is to prepare a written recommendation to send back to you, explaining which BMPs you can install to reduce the likelihood of creating water pollution.

The site evaluation report will categorize BMPs into four basic categories:

  1. Paving Driveways and Parking Areas: A driveway permit and a professional design are required to ensure that runoff will not flow to the street or roadside ditch. The reason we pave driveways at Tahoe is to prevent unpaved driveways from being sources of soil and mud to be tracked onto the street by departing cars. This mud is washed into the storm drain system. In addition, during rainstorms water containing harmful sediment will run off the compacted dirt surface and often enter the street drain system, which carries the dirty water eventually to the lake. Runoff from the impervious surface must be conveyed to an infiltration system, which is the next category.
  2. Infiltration Systems: Since water from a rainstorm or melting snow will run off all the rooftops, patios, walkways and driveways on your lot, your soil usually is not capable of soaking up all that water. Infiltration systems are merely devices that catch and store the runoff, often underground, from your “impermeable” surfaces so that it has time to percolate down into the soil. Since most runoff from homes is relatively nontoxic, its pollutants are easily filtered by the soil. The clean water reaches the water table, which can eventually return it to streams or the lake. One important exception is plant fertilizer. If you overfertilize your landscape, the nitrogen and phosphorus that sinks to the water table will eventually reach and pollute the lake.
  3. Vegetation and Mulch on Bare Soil: Most people realize that heavy rainfall on bare soil is a recipe for soil erosion. The BMPs in this category include planting native and adapted plants, as listed and pictured in Chapter 7 of the “Home Landscaping Guide for Lake Tahoe and Vicinity.” This book comes free with the site evaluation described above. Mulch is a material such as wood chips, bark chips, composted pine needles, or gravel that is spread on top of the soil to protect it. Both vegetation and mulch promote the infiltration of water into the soil and reduce the ability of raindrop impact to erode soil particles.
  4. Slope Stabilization: This category includes the planting of erosion-control vegetation on gentle slopes. It also includes the installation of structures such as terraces, retaining walls, or gravity block walls, or using bioengineered methods on slopes greater than 50 percent. Bioengineered methods involve placing cuttings of dormant willow shrubs into slopes, often horizontally along the contour, and irrigating the cuttings so that they grow to form a strong, vigorous stand of willow bushes that keep even, steep slopes from eroding. This method can provide a unique gardening challenge for full-time residents with a green thumb.

The Lake Tahoe Report 023

Air Date: 2003.07.08

Video Segment: BMPs - 5 Main Types

Interviewees: Jennifer Jespersen (TRCD)

Adopt-A-Watershed * Lake Tahoe Basin & Truckeee River Watershed * Revised 6/17/04