- A - watershed area
- AB - total allowable drainage area to buffer
- AC - natural area conserved
- AD - area disconnected
- Ar - filter bed area
- As - surface area, sedimentation basin
- BMPRE - BMP removal efficiency for total phosphorus
- C - flow–weighted mean concentration of the pollutant in urban runoff
- Ca - calcium
- CaCl2 - calcium chloride
- Cl - chloride
- CMA - calcium magnesium acetate
- Vcp-ED - extended detention of the 1–year post–development runoff
- Cu - copper
- DA - % Served fraction of the drainage area served by the BMP
- df - depth of filter bed
- fcsoil - infiltration rate
- FCN - free cyanide
- Fe - iron
- hf - head above filter bed
- Hg - mercury
- I - impervious cover
- Ia - initial abstraction
- IC - percent new impervious cover
- Ipost - post–development site imperviousness
- K - coefficient of permeability
- KAc - potassium acetate
- KFo - potassium formate
- L - pollutant loading
- Lpost - average annual load of total phosphorus exported from the post–development site
- Lpre - average annual load of total phosphorus exported from the site prior to development
- LR - annual total phosphorus load removed by the proposed BMP
- Mg - magnesium
- MgCl2 - magnesium chloride
- N - nitrogen
- Na - sodium
- NaCl - sodium chloride
- NH3 - ammonium
- NOx - nitrogen oxides
- P - precipitation depth
- P - phosphorus
- Pj - fraction of rainfall events that produce runoff
- Qf - extreme flood storage volume
- Qi - peak inflow discharge
- Qo - peak outflow discharge
- Qp10 - overbank flood control storage rate
- Qp100 - extreme storm control storage rate
- qp - water quality peak discharge
- qu - unit peak discharge
- r - volume of stormwater runoff
- Rea - recharge area requiring treatment
- Rev - recharge volume
- RR - pollutant removal requirement
- Rv - volumetric runoff coefficient expressing fraction of rainfall that is converted to runoff
- S - soil specific recharge factor
- tc - time of concentration
- tt - time to drain filter bed
- Vcp - channel protection volume
- Vp10 - overbank flood control storage volume
- Vp100 - extreme storm control storage volume
- Vpp - permanent pool volume
- Vr - rainfall runoff volume
- Vre - recharge volume
- Vs - snowmelt runoff volume
- Vt - total volume
- Vts - total storage volume
- Vv - volume of voids
- Vwq - water quality volume
- Vwq ED - extended detention water quality volume
- Zn - zinc