Setting the Course for Improve d Wa ter Qua litlity Hyygydrology in Watershed Systems

Photo by Don Berger Minnesota Pollution Control Agency Session 5A: A TMDL traininggp prog ram f or local g overnment leaders and other water resource managers

wq-iw3-55a Hydrology is one of many disciplines iildiTMDLtdinvolved in TMDL studies y cc l Agen o o Biology Contr ollution P P SilSocial Water sciences sota sota chemistry ee Minn In this presentation y cc BiBasic pri iilnciples of fhdl hydrology l Agen oo Sources and pathways of flow in watersheds Contr Importance of hydrology to

ollution TMDL studies and water PP quality management sota sota ee Minn Watersheds integrate physical, chilbililhemical, biological processes y cc „ A watershed is an area of land that drains to a common point l Agen oo „ TMDL s tu dies use watersheds as the

Contr bioppyhysical basis for water quality planning and management ollution „ Watersheds integrate PP physical, chemical and biological sota sota ee processes Minn Minnesota Pollution Control Agency This module focuses on watershed hydrology What is “hydrology?” y cc “The study of water in l Agen

oo all its forms (liquid, gas, and solid) on, in and over the land areas of Contr the earth” – Michigan DEQ ollution PP sota sota ee Hydrology is important at a global, regional or watershed scale Minn Hydrologic processes affect water quality y cc The movement of l Agen surface and oo groundwater results in the transport and Contr delivery of pollutants to waterbodies ollution PP sota sota ee Minn The hydrologic cycle y cc l Agen oo Contr ollution PP sota sota ee

Minn c/o US EPA Why is hydrology important to TMDL s tu dies ? y cc Hydrology is critical to Before we can manage understanding the an impaired waterbody, l Agen sources and movement o o we must understand watershed hydrology of water (and pollutants) to a waterbody Contr

Addressing water quality problems in water bodies will ollution require addressing hydrologic pathways P P (i.e. reducing surface runoff, increasing infiltration, etc.) sota sota ee Minn Sources of water affecting stfltream flow y cc Precipitation is the l Agen

oo major source of new Each watershed also water in watersheds stores existing water Contr ollution PP sota sota ee Minn Types of precipitation contributing wattter to wa tersh hdeds y cc raifllinfall

l Agen drizzle oo snow

Contr sleet hail ollution P P fog sota sota

ee dew frost Minn Precipitation affects the „ amount „ timing „ distribution „ quality of water moving through a watershed Minnesota Pollution Control Agency activities that canchange decisions andhuman precipitation Humans cannotcontrol watersheds intercepted andstoredin is precipitation much how They cancontro

much

precipitation l land use

is

Water storage and movement

y „ A watershed is essentially cc an enormous precipitation collecting, storing and

l Agen routing device oo „ Storage and movement of water within watersheds Contr ilinvolves a comp lex combination of many smaller processes ollution PP „ Infiltration and storage of precipitation minimizes sota sota ee surface runoff and reduce the movement of

Minn pollutants to streams Water storage on earth can be natltural or man-made y cc any natural or man-made surface where Depression water collects and either seeps or l Agen storage evaporates (lakes, wetlands, ponds, oo reservoirs, etc.) Soil water water held within the soil Contr

Vegetation used by plants ollution

PP GdtGroundwater sattdturated zone ( aqu if)ifers) Channel

sota sota water held within the channel ee storage (stream, river, ditch)

Minn – Adapted from Peter Block, 2002 Water movement in a watershed y cc The pathways for precipitation,

l Agen from rainfall to stream flow, o o involves a combination of surface and sub-surface processes Contr

Difficult to separate the various ollution P P pathways of flow sota sota

ee Water can move between sources (source interactions) Minn Hyygpydrologic pathways in a watershed

Evapotranspiration Precipitation

Surface Channel runoff interception Infiltration & Water subsurface table flow Groundwater or base flow Channel storage (stream flow) Adapted from Kenneth Brooks, et. al., 2003 Ground water recharge and disc harge zones in wa ters he ds y cc the process of water soaking into the ground Recharge

l Agen to replenish ground water aquifers oo a process by which subsurface water Discharge Contr becomes surface water ollution PP sota sota ee Minn Groundwater recharge zones within a wa ters he d y cc Recharge occurs in

l Agen specific areas of a oo watershed Contr

The nature and timing of ollution

PP recharge depends on excessive water infiltration and sota sota ee percolation beyond plant roots Minn Groundwater recharge and disc harge zones y cc l Agen oo Contr ollution PP sota sota ee

Minn c/o USGS Groundwater discharge zones ithdin a watershed

y „ Time needed for water to move from recharge cc zones to discharge points can be minutes to years l Agen oo „ Groundwater discharging to surface waters is mostly unseen, but if observed, is typically Contr seen as springs or seeps „ Groundwater discharges to surface waters can ollution

PP greatly affect temperature, dissolved oxygen and other characteristics of water which can sota sota

ee affect aquatic life Minn Drainage systems may impact the rechfharge of some deep aqu ifers y cc l Agen oo

Subsurface tile drainage Contr

lake ollution PP Deep aquifer sota sota ee Minn Minnesota Pollution Control Agency interactions in watersheds Surface / g roundwater Surface water / groundwater itinteracti ons

y Ground and cc surface water are often l Agen oo treated as separate

Contr systems – however, they are ollution

PP inextricably They should linked be studied as sota sota ee an integrated system Minn Surface water / groundwater itinteracti ons

y „ Pathways of the interaction cc are complex „ Interactions are neither l Agen oo constant, nor consilistently separate

Contr „ Groundwater is the major source of base flow in

ollution many Minnesota streams PP sota sota ee Minn Groundwater / surface water interactions can result in ga in ing or los ing s tream reac hes

GainingGainingGaining LosingLosingLosing stream reach stream reach

WblWater table

Water table Ground water Wetlands are an expression of ground- water andfd surface watitter interacti ons y cc l Agen oo

Contr Photo: BWSR Photo: BWSR ollution PP sota sota ee

Photo: NRCS Minn Wetlands with unusual groundtittidwater interactions y cc l Agen oo Contr c/o Scott County Bogs Fens ollution P P PerchedPhd water table Ground – water rich sota sota in calcium e e Regional water table carbonate Minn Summary y

cc „ Hydrology concerns water in all its forms on, in and over the land areas of the earth l Agen oo „ The hydrologic cycle feeds flow in our streams, ultimately affecting water quality Contr „ WtWater st orage and movement ti invol ves a complex combination of many processes ollution PP sota sota ee Minn Summary y

cc „ Specific areas within a watershed serve as recharge and discharge zones l Agen oo „ Surface water in lakes, streams and wetlands interacts with groundwater Contr „ BdtdihdlithBy understanding hydrologic pathways, we can influence water quantity and quality ollution PP sota sota ee Minn Now what? y cc Now we understand the importance of hydrology in watershed management. l Agen o o What do we do with that knowledge? Contr

Use the following modules and worksheets to ollution P P hlhelp you scope and p lan your pro ject. sota sota ee Minn What’ s next? y c c Future modules will address other disciplines related to watershed management: l Agen o o

Biology Contr Water chemistry ollution P P sota sota

ee (watershed assessment: land use, land cover, geography, soils, etc.) Minn Final thought

y “A watch is compp,licated, but a cc watershed is complex. Remove one gear from the thousands in a watch l Agen

oo and it , predictably , stops working. Pollute one river and the whole

Contr watershed is likelyyg to shift and change in a thousand ways, but nobody can be quite sure if or when a toxic algal ollution bloom will appear in the lake. ” PP - Dr. Judith Van Houten

sota sota University of Vermont ee Minn