Management Goals for Maryland Stream Gages

• Modeling and model calibration
• Evaluation of current conditions and trends
• Watershed management and planning (land use and land use changes)
• Regional and area assessment - Impacts & Problem Assessments (USGS goal: Spatial Coverage)
• Design (especially bridge and culvert)
• Water quality (loadings, regulation/compliance, BMP's, TMDL's)
• Stream restoration
• Forecasting and effects: flood and drought
• Recreational uses
• Water supply
• Ecosystem/living resources (fish kills, Pfiesteria)
• Legal obligations
• Research

Management Goal - Local Watershed Management and Restoration

Objective - Calibrate field indicators of the bankfull channel to known streamflows for use in geomorphic assessments in gaged and ungaged watersheds.

Action - Develop regionalized regression equations/curves of drainage area to bankfull channel dimensions from gaged watersheds within the various hydrophysiographic provinces and major land use categories.

Objective - Develop reliable estimates of bankfull and peak discharges for use in:

• design of highway bridges and culverts
• design of flood control and stormwater management facilities
• design of stream restoration/relocation projects
• flood studies and planning of floodplain reservation.

Action - Develop regionalized regression equations/curves of drainage area to bankfull discharge from gaged watersheds within the various hydrophysiographic provinces and major land use categories.

Action - Establish a streamflow database that can be utilized to calibrate the hydrologic models used in engineering studies and designs in ungaged watersheds.

Needs - Gage network that meets the following criteria:

• Annual maximum peaks recorded
• Minimum period of record greater than ten (10) years
• Gaged watersheds within each hydrophysiographic province with the following characteristics:
  • Small (<5 mi²)
    • Rural (forest, agriculture, <11% impervious)
    • Suburban (residential/commercial, 11-30% impervious, forest, agriculture)
    • Urban (residential/commercial/institutional, >30% impervious)
  • Intermediate (5-50 mi²)
    • Rural
    • Suburban
    • Urban
  • Large (>50 mi² )
    • Rural
    • Suburban
    • Urban
• A sufficient number of each type to provide statistically significant data.

Management Goal - Water Quality Management, Modeling and Remediation

Objective - Provide discharge data for calibration of watershed pollutant loading models based on land use and watershed size. The model results will allow targeting of remediation efforts.

Action - Provide sufficient gage coverage to calibrate models in every watershed. Such gage coverage needs to include both small scale and large scale watersheds and a range of land use types.

Action - Provide sufficient water quality concentration (both baseflow and storm event) data at gage stations for calibration and verification of water quality models.

Objective - Assess results of remediation efforts on a subwatershed scale.

Action - Provide gages on subwatersheds targeted for remediation efforts to measure results on a subwatershed scale using water quality monitoring data in conjunction with gage discharge data.

Objective - Provide gages on relatively undeveloped watershed to measure the effect of the new storm water management design criteria on the stream system. This will be a NPDES - Municipal Stormwater Discharge Permit requirement during the next five year term of the permit.

Action - Identify subwatersheds that are currently undeveloped, but are expected to undergo development with the new design criteria in place. Provide for the installation of gages on several of these systems prior to development to provide baseline data.

Needs - Gage network that meets the following criteria:

• Recording of discharge data in 15 minute intervals, with sufficient measurement to provide rating curves.
• Gages within most of Baltimore County's subwatersheds to provide information for model calibration.
• Specifically targeted gages to measure the effect of the new storm-water management design criteria.
• The range of characteristics of hydrophysiographic province, size and land use indicated above for Local Watershed Management and Restoration.
• A sufficient number of each type to provide information on the variability of the data and potentially allow statistically significant conclusions to be drawn.

Management Goals - General

• Ensure a core network of gages so that state, regional and county surface water assessments can be made.
• Ensure that trends and conditions in surface water flow that may result from climate and land-use changes can be monitored.
• Coordinate and collaborate stream gaging efforts with those state, regional and local entities requiring stream flow data.

Objective - Spatial Coverage

"What I would most like to see out of the gage network is improved spatial coverage in all physiographic provinces in Maryland. My needs (for the most part) include flood hydrology and probability, stream geometry characteristics, river hydraulics, and analysis of channel-forming (i.e. bankful) discharges."