Twain Harte School Stormwater Enhancement Project

3 Documents in Project


SCH Number
Public Agency
Tuolumne County Resource Conservation District (TCRCD)
Document Title
Twain Harte School Stormwater Enhancement Project
Document Type
NOE - Notice of Exemption
Document Description
The Tuolumne County Resource Conservation District (TCRCD) acting as the Lead Agency, will implement stormwater mitigation activities Considering the site receives stormwater flow from the adjacent community market, which experiences high vehicular use, bioswales have been designed to filter and treat water entering the site. Additional strategies to reduce water demand while decreasing runoff include a 40,000 gallon above ground stormwater tank to capture runoff and reuse for turf irrigation, bank of five, 5,000-gallon rain tanks capturing rainwater off the Gymnasium and adjacent classroom. This storage will blend with the captured stormwater for 5.52-acre feet per year irrigation offset. The overflow from these tanks will flow into bioswales to slow velocities, reduce nuisance flooding and winter ice hazards, create habitat, and recharge groundwater before entering the Tuolumne County storm drain system (see Tuolumne County Storm Drain Rehabilitation Project). An additional 5,000-gallon rain tank will be installed off the Music Room to offset irrigation demand for the school garden. This tank would also serve to reduce nuisance local flooding and winter ice hazards. The overflow from this system, as well as sheet flow entering from the adjacent roadway, will be treated in a bioswale (previously constructed as part of this project through TCRCD DWR funding). Lastly, to reduce nuisance flooding to downtown business, at the lower slope of the property, a rain garden will be placed at the center of the bus and automobile drop off area, near the lowest spot on the property. This strategic raingarden will capture and filter stormwater running across the site before entering the storm drain system. This will serve to create habitat for native species and demonstrate LID treatments in a highly visible area. In total, the bioswales and rain garden at the school will treat 7.4-acre feet of water per year. Highly visible signage will be installed to educate the community to encourage similar improvements on private properties across the community. Treatment activities, including the installation of bioswales and a rain garden, and tank and pad installation for rainwater capture and reuse with irrigation attached will be conducted under this Notice of Exemption (NOE).

Contact Information

Lindsay Mattos
Agency Name
Tuolumne County Resource Conservation District
Job Title
District Manager
Contact Types
Lead/Public Agency


Northern California
Cross Streets
18815 Manzanita Dr
Twain Harte School

Notice of Exemption

Exempt Status
Categorical Exemption
Type, Section or Code
Section 15304
Reasons for Exemption
The RCD has determined that the project's implementation will result in multiple benefits, including stormwater reduction, watershed improvement, and wildlife habitat enhancement Project is located on less than 5 acres and surround by commercial and public land uses and as such has no value for endangered, rare or threatened species or their habitats. There are no hazardous materials at or around the project site. The project will avoid all archeological resource sites. The project will not result in cumulatively significant impacts. The project will have no significant adverse effect on the environment, traffic, air, or water quality.
County Clerk


Disclaimer: The Governor’s Office of Planning and Research (OPR) accepts no responsibility for the content or accessibility of these documents. To obtain an attachment in a different format, please contact the lead agency at the contact information listed above. You may also contact the OPR via email at or via phone at (916) 445-0613. For more information, please visit OPR’s Accessibility Site.

Download CSV New Search Print